Electrophotographic recording medium containing .tau. and .eta. metal-free phthalocyanine

A recording medium for electrophotography comprising a thin layer containing an effective amount of .tau. form metal-free phthalocyanine or .tau.' form metal-free phthalocyanine which is obtained in such a way that .alpha. form metal-free phthalocyanine is dispersed in a liquid dispersant;

• while the dispersed system is heated to a temperature lower than a decomposition temperature of the phthalocyanine, mechanical shearing forces are applied to the dispersed phthalocyanine particles, to change a crystalline structure thereof, and an electroconductive substrate supporting the layer thereon.

A recording medium for electrophotography comprising a thin layer containing an effective amount of .eta. form or .eta.' form metal-free phthalocyanine which is obtained in such a way that a mixture is dispersed in a liquid dispersant, said mixture comprising (A) 100 parts by weight of metal-free phthalocyanine and (B) at most 50 parts by weight of at least one, metal-free phthalocyanines;

• while the dispersed system is heated to a temperature lower than a decomposition temperature of the above-mentioned mixture, mechanical shearing forces are applied to this mixture, to change a crystalline structure thereof, and an electroconductive substrate supporting the layer thereon.

A composite recording medium for electrophotography comprising a layer containing a charge generating substance and a charge transport substance, said layer being disposed on an electroconductive substrate, wherein said charge generating substance contains at least one member selected from the group consisting of .tau., .tau.', .eta. and .eta.' form metal-free phthalocyanine metal-free phthalocyanine.

A recording medium for electrophotography comprising an electroconductive substrate, and a thin layer, supported on the substrate, containing an effective amount of a metal-free phthalocyanine selected from the group consisting of .tau.-form metal-free phthalocyanine, .tau.'-form metal-free phthalocyanine and a mixture thereof, wherein .tau.-form and .tau.'-form metal-free phthalocyanines are characterized by intense lines at Bragg angles (2.theta..+-.0.2 degrees) of 7.6, 9.2, 16.8, 17.4, 20.4 and 20.9, and 7.5, 9.1, 16.8, 17.3, 20.3, 20.8 and 27.4, respectively.

A recording medium for electrophotography comprising an electroconductive substrate, and a thin layer, supported on the substrate, containing an effective amount of a metal-free phthalocyanine selected from the group consisting of .eta.-form metal-free phthalocyanine, .eta.'-form metal-free phthalocyanine and a mixture thereof, wherein the .eta.- and .eta.'-form metal-free phthalocyanines each comprises 100 parts by weight of a metal-free phthalocyanine and up to 50 parts by weight of at least one of a metal-free phthalocyanine having a substituent for benzene nuclei, a porphin-type compound, a metal phthalocyanine which may have a substituent for benzene nuclei, and the .eta.-form and .eta.'-form are characterized by intense lines at Bragg angles (2.theta..+-.0.2 degrees) of 7.6, 9.2, 16.8, 17.4 and 28.5, and 7.5, 9.1, 16.8, 17.3, 20.3, 20.8, 21.4 and 27.4, respectively.