Electrophotographic element containing disazo compounds

Claim 1

An electrophotographic element comprising an electroconductive substrate, a charge generating layer and a charge transport layer, said charge generating layer comprising a disazo pigment having the general formula: ##STR8## wherein A is a member selected from the group consisting of ##STR9## is a fused ring selected from the group consisting of benzene ring, halobenzene ring, naphthalene ring, indole ring, carbazole ring and benzofuran ring; Ar 1 is a member selected from the group consisting of phenyl, methylphenyl, methoxyphenyl, chlorophenyl, nitrophenyl, ethoxyphenyl, methylchlorophenyl, dimethylphenyl, methoxychlorophenyl, methoxybromophenyl, methoxymethylphenyl, dimethoxyphenyl, dimethoxychlorophenyl, dimethylaminophenyl, cyanophenyl, carboxyphenyl, benzenesulfonic acid sodium salt, tert-butoxyphenyl, naphthyl, methoxydibenzofuryl and carbazolyl; each of Ar 2 and Ar 3 is a member selected from the group consisting of phenyl, naphthyl, methoxyphenyl, methylphenyl, acetylaminophenyl, dimethylaminophenyl, cyanophenyl, nitrophenyl, dinitrophenyl, chlorophenyl, trichlorobenzenesulfonic acid, benzenesulfonic acid and benzenesulfonamide; each of R 1 and R 3 is a member selected from the group consisting of hydrogen, methyl, ethyl, phenyl and chlorophenyl; and R 2 is a member selected from the group consisting of methyl, carboxyl and --COOC 2 H 5 , and a binder material consisting essentially of a mixture of polyvinyl butyral and acrylic resin, wherein the weight ratio of polyvinyl butyral to acrylic resin in said mixture is in the range of from 0.1:1 to 1:0.1, the amount of said mixture is 10 to 200% by weight, based on the weight of said disazo pigment, the thickness of said charge generating layer is in the range of from about 0.05 micron to about 2 microns and the thickness of said charge transport layer is in the range of about 5 microns to about 100 microns.