Electrophotographic photosensitive member, process cartridge, and image forming apparatus

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer, wherein

• the photosensitive layer is a single-layer photosensitive layer and contains a charge generating material, a hole transport material, an electron transport material, and a binder resin,
• the binder resin has a viscosity average molecular weight of at least 25,000 and no greater than 50,000,
• a strain at break of the photosensitive layer is at least 4.9% and no greater than 13.0%, the strain at break being a value determined from a stress-strain curve obtained by pulling the photosensitive layer using a tensile tester at a rate of 5 mm/minute,
• a scratch resistant depth of the photosensitive layer is no greater than 0.50 μm, the scratch resistant depth being a value measured through first to fourth steps described below using a scratching apparatus in accordance with JIS K5600-5-5,
• the scratching apparatus includes a fixture and a scratching stylus,
• the scratching stylus has a semispherical sapphire tip having a diameter of 1 mm,
• in the first step, the photosensitive member is fixed to an upper surface of the fixture with a longitudinal direction of the photosensitive member in parallel with a longitudinal direction of the fixture,
• in the second step, the scratching stylus is brought into vertical contact with a surface of the photosensitive layer,
• in the third step, the fixture and the photosensitive member fixed to the upper surface of the fixture are caused to move by 30 mm at a rate of 30 mm/minute in the longitudinal direction of the fixture while a load of 10 g is applied from the scratching stylus to the photosensitive layer,
• in the fourth step, the greatest depth of a scratch created on the surface of the photosensitive layer through the third step is measured as the scratch resistant depth, and
• the binder resin includes a polyarylate resin represented by general formula (1) shown below
• where in general formula (1),
• r, s, t, and u each represent, independently of one another, a number greater than or equal to 0
• r+s+t+u=100,
• r+t=s+u,
• r/(r+t) is at least 0.00 and no greater than 0.90,
• s/(s+u) is at least 0.00 and no greater than 0.90,
• X is a divalent group represented by chemical formula (1A) or (1B) shown below, and
• Y is a divalent group represented by chemical formula (2A) or (2B) shown below