Electrophotographic photosensitive member, process cartridge, and image forming apparatus

An electrophotographic photosensitive member comprising:

• a conductive support;
• a charge generation layer disposed on the conductive support, the charge generation layer including:
• a charge generating material;
• and
• a vinyl copolymer, the vinyl copolymer including:
• a structural unit including a chlorine atom,
• a structural unit including an acyloxy group, and
• a structural unit including an aromatic polycarboxylic acid structure,
• a proportion of the structural unit including a chlorine atom to all the structural units constituting the vinyl copolymer being 80% by mass or more, a proportion of the structural unit including an aromatic polycarboxylic acid structure to all the structural units constituting the vinyl copolymer being 0.5% by mass or more;
• and
• a charge transport layer disposed on the charge generation layer, the charge transport layer including:
• a charge transporting material;
• and
• a binder resin.