Process cartridge

A process cartridge detachably attachable to an electrophotographic apparatus main body, the process cartridge comprising:

• a toner;
• and
• a developing roller, wherein
• (I) the toner includes toner particles, and a cohesion cluster containing fine silica particles and a binder component is present on surfaces of the toner particles,
• an arithmetic mean value Ag of a Feret diameter of the cohesion cluster is 500 nm or more and 8,000 nm or less,
• when a number percentage of toner particles having the cohesion cluster is represented by CI (number %), CI is 1 number % or more and 15 number % or less, and
• when a number percentage of toner particles having the cohesion cluster in the toner after being treated under an ultrasonic wave condition A is represented by Ca (number %), and a number percentage of toner particles having the cohesion cluster in the toner after being treated under an ultrasonic wave condition B is represented by Cb (number %), CI, Ca, and Cb satisfy formulae (1) and (2),
• ultrasonic wave condition A:
• output frequency 30 kHz, output capacity 0.75 W, and irradiation time 300 s
• ultrasonic wave condition B:
• output frequency 30 kHz, output capacity 30 W, and irradiation time 300 s
• 0.9
• ≤
• Ca
• /
• CI
• ≤
• 1.
• Formula
• ⁢
• (
• 1
• )
• 0.05
• ≤
• Cb
• /
• CI
• ≤
• 0.25
• ,
• Formula
• ⁢
• (
• 2
• )
• and
• (II) the developing roller includes a conductive shaft member and at least one elastic layer on the conductive shaft member, and the developing roller has an Asker C hardness of 56 degrees or more and 75 degrees or less.