Dual layer electrophotographic recording material

Claim 1

In an electrophotographic recording material comprising an electroconductive support material with a photoconductive double layer of organic materials composed of a tightly packed, homogeneous, uniform, opaque charge carrier producing dyestuff layer prepared by vacuum evaporation of the dyestuff and a transparent top layer of insulating materials containing at least one charge transporting compound, the improvement in which the organic dyestuff layer consists of a compound of the general formula ##EQU3## wherein A is a diphenyl or azobenzene group which may be substituted by alkyl with 1 to 4 carbon atoms, alkoxy with 1 to 4 carbon atoms, and/or halogen, R and R 1 which may be the same or different, are alkyl with 1 to 4 carbon atoms or carbalkoxy in which the alkyl groups have from 1 to 4 carbon atoms, and R 2 and R 3 are phenyl groups which may be substituted by alkyl with 1 to 4 carbon atoms, and in which said transparent top layer consists of a mixture of a binder selected from the group consisting of polyester, copolyester, silicone resin, styrene/maleic anhydride copolymer and polycarbonate resin with a charge transporting, monomeric, heterocyclic compound selected from the group consisting of oxazoles, oxdiazoles, triazoles, imidazoles and pyrazoles substituted by at least one dialkylamino group or two alkoxy groups and having an extended π-electron system, in which the dyestuff layer has a thickness of about 0.05 to about 2 microns and the transparent top layer has a thickness of about 5 to about 20 microns and in which the transparent top layer consists of about a 1 : 1 mixture by weight of the charge transporting heterocyclic compound and the binder, said recording material having a high mechanical resistance and good adhesion between the various layers and being useful in an electrophotographic copying process with negative charging of the top layer if an electron donating compound is used.