Electrophotographic photosensitive plate

Claim 2

An electrophotographic photosensitive plate, comprising an electroconductive layer, a photoconductive layer thereon, and a protective polymer coating layer on the opposite surface of said photoconductive layer, said protective coating having a thickness not greater than one micron and comprising polyvinyl butyral having a butyralation degree of 57 to 65 mole percent and a cellulose derivative selected from the group consisting of cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetobutyrate, and cellulose nitrate, said polyvinyl butyral being present in said coating in an amount varying from 50 to 90 percent by weight, and said cellulose derivative being present in said coating in an amount ranging from 10 to 50 percent, by weight, said protective polymer coating layer having a volume resistivity no greater than 1015 ohm-cm.

Claim 3

An electrophotographic photosensitive plate as claimed in claim 1, wherein the protective polymer coating layer is composed of 50 to 80 percent by weight of polyvinyl butyral and 20 to 50 percent by weight of cellulose nitrate.

Claim 4

An electrophotographic photosensitive plate as claimed in claim 1, wherein the protective polymer coating layer is composed of 70 to 90 percent by weight of polyvinyl butyral and 10 to 30 percent by weight of cellulose diacetate.

Claim 5

An electrophotographic photosensitive plate as claimed in claim 1, wherein the protective polymer coating layer is composed of 72 to 80 percent by weight of polvinyl butyral and 20 to 28 percent by weight of cellulose triacetate.

Claim 6

AN ELECTROPHOTOGRAPHIC PHOTOSENSITIVE PLATE WHICH COMPRISES, ON A SUPPORT OF AN INORGANIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF ALUMINUM, ZINC, BRASS, COPPER, AND ELECTROCONDUCTIVE GLASS, A PHOTOCONDUCTIVE, LAYER MADE OF A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF SELENIUM, SELENIUM-TELLURIUM, ZINC OXIDE, LEAD OXIDE AND CADMIUM SULFIDE AND A PROTECTIVE POLYMER COATING LAYER COATED ON THE OPPOSITE SURFACE OF SAID PHOTOCONDUCTIVE LAYER, SAID PROTECTIVE COATING HAVING A THICKNESS NOT GREATER THAN ONE MICRON AND COMPRISING A POLYVINYL BUTYRAL HAVING A BUTYRALATION DEGREE OF 57 TO 65 MOLE PERCENT AND A CELLULOSE DERIVATIVE COMPBATIBLE WITH SAID POLYVINYL BUTRYAL, SAID POLYVINYL BUTYRAL BEING PRESENT IN SAID COATING IN AN AMOUNT VARYING FROM 50 TO 90 PERCENT, BY WEIGHT, AND SAID CELLULOSE DERIVATIVE BEING PRESENT IN SAID COATING IN AN AMOUNT RANGING FROM 10 TO 50 PERCENT, BY WEIGHT, SAID PROTECTIVE POLYMER COATING LAYER HAVING A VOLUME RESISTIVITY NO GREATER THAN 10**15 OHM - CM.

Claim 7

AN ELECTROPHOTOGRAPHIC PHOTOSENSITIVE PLATE WHICH COMPRISES, ON A SUPPORT OF AN INORGANIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF ALUMINUM, ZINC, BRASS, COPPER, AND ELECTROCONDUCTIVE GLASS, A PHOTOCONDUCTIVE, LAYER MADE OF A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF SELENIUM, SELENIUM-TELLURIUM, ZINC OXIDE, LEAD OXIDE AND CADMIUM SULFIDE AND A PROTECTIVE POLYMER COATING LAYER COATED ON THE OPPOSITE SURFACE OF SAID PHOTOCONDUCTIVE LAYER, SAID PROTECTIVE COATING HAVING A THICKNESS NOT GREATER THAN ONE MICRON AND COMPRISING A POLYVINYL BUTYRAL HAVING A BUTYRALATION DEGREE OF 57 TO 65 MOLE PERCENT AND A CELLULOSE DERIVATIVE COMPBATIBLE WITH SAID POLYVINYL BUTRYAL, SAID POLYVINYL BUTYRAL BEING PRESENT IN SAID COATING IN AN AMOUNT VARYING FROM 50 TO 90 PERCENT, BY WEIGHT, AND SAID CELLULOSE DERIVATIVE BEING PRESENT IN SAID COATING IN AN AMOUNT RANGING FROM 10 TO 50 PERCENT, BY WEIGHT, SAID PROTECTIVE POLYMER COATING LAYER HAVING A VOLUME RESISTIVITY NO GREATER THAN 10**15 OHM - CM.

Claim 8

An electrophtographic photosensitive plate, as claimed in claim 1 wherein said protective polymer coating layer also contains 3 to 8 percent of ethyl cellulose.