Patent GB-693112-A (GB)
Title: Electrophotographic plate and method of producing same
IPC: H01B3/30
Filed: 1950-05-09
Abstract: A composition useful in the production of electrophotographic plates consisting of a conducting support and a photoconducting insulating material (see Group XX), comprises a solution in a volatile organic solvent of a binder consisting of polystyrene, a silicone resin, an acrylic resin, or a vinyl-chloride-acetate resin; and one or both of the amorphous or a -monoclinic forms of selenium dispersed uniformly throughout the binder which has a resistivity higher than that of the selenium and the conducting support of the electrophotographic plate. The composition, which is preferably applied to a polished metal, or a metal-coated glass base plate by spraying, may be a ball-milled mixture, held below 50 DEG  C. and thinned with toluene for spraying, of amorphous (ball-milled vitreous) selenium with (1) a mixture in iso-butylketone of vinyl chloride-vinyl acetate copolymer and a similar copolymer, modified by a small amount of an interpolymerized dibasic acid; or (2) a silicone resin in toluene; or (3) polystyrene in xylene; or (4) a polymerized ester derivative of acrylic and a -methyl acrylic acids in "Cellosolve" (Registered Trade Mark) acetate; or (5) a similar ester derivative in toluene.  The volume of selenium in the mixture may be only 1/7 of the volume of binder but preferably the mixture contains 1 part selenium to 1 to 2 parts of binder, while the total volume of solvent used in a spraying composition may be 0.5 to 3.0 times the volume of binder, but preferably is about the same volume.  Instead of selenium, there may be used as the photo-conducting insulating material sulphur, zinc titanate, acenaphthene, anthracene, anthraquinone, benzidine, chrysene, fluoranthene, pyrogallic acid, quinone, microcrystalline paraffin wax, or mixtures of sulphur and anthracene, and of sulphur and selenium, while alternative binder solvents are benzene, petrol, an aromatic petroleum product or mixtures of any of those named above.ALSO:A composition, useful in producing electrophotographic plates comprising a conducting support and a photoconducting insulating material (see Group XX) comprises a solution in a volatile organic solvent of a binder consisting of chlorinated rubber, and one or both of the amorphous or a -monoclinic forms of selenium dispersed uniformly throughout the binder which has a resistivity higher than the selenium and the conducting support of the electrophotographic plate.  The composition, which is preferably applied to a metal or metal-coated glass base plate by spraying, may be a ball-milled mixture in toluene, held below 50 DEG C. and thinned for spraying with toluene, of amorphous selenium with chlorinated rubber and an alkyd resin plasticizer containing 60 per cent. linseed oil and 40 per cent. glycerol phthalate.  The volume of selenium in the mixture may be only 1/7 of the volume of binder but preferably the mixture contains 1 part selenium to 1 to 2 parts of binder, while the total volume of solvent used in a spraying composition may be 0.5 to 3.0 times the volume of binder and preferably is about the same volume. Instead of selenium, there may be used as the photoconducting insulating material sulphur, zinc titanate, acenaphthene, anthracene, anthraquinone, benzidine, chrysene, fluoranthene, pyrogallic acid, quinone, microcrystalline paraffin wax, or mixtures of sulphur and anthracene and of sulphur and selenium, while alternative binder solvents are benzene, "Cellosolve" (Registered Trade Mark) acetate, methyl iso-butyl ketone, xylene, petrol, an aromatic petroleum product, or mixtures of any of those named above.