Electrophotographic photoreceptor, and image forming apparatus and process cartridge therefor using the photoreceptor

An electrophotographic photoreceptor, comprising a charge generation layer over an electroconductive substrate, and a charge transport layer on the charge generation layer,

• wherein the charge generation layer comprises titanylphthalocyanine and a binder resin which is a crosslinked material of a resin comprising a polyvinylbutyral site having the following formula (1) and an isocyanate compound having the following formula (4):
• wherein R1 and R2 independently represent an alkyl group having 1 to 3 carbon atoms;
• k, l, m and n represent composition ratios and k+1 is from 0.60 to 0.80, wherein k or 1 may be 0, m is from 0.02 to 0.03, and n is from 0.20 to 0.40;
• wherein A3 represents a substituted or an unsubstituted non-aromatic hydrocarbon group or an aryl group;
• Ar1 represents a substituted or an unsubstituted aromatic ring;
• R3 and R4 independently represent a divalent organic group having 1 to 3 carbon atoms when A3 is a non-aromatic hydrocarbon group and a single bond when A3 is an aryl group;
• and q represents an integer of from 2 to 4.