Process cartridge

A process cartridge that is mountable on an image forming apparatus, the process cartridge comprising:

• a developing chamber,
• wherein the developing chamber includes
• a developing roller that develops an electrostatic latent image formed on a surface of a photosensitive drum using a toner to form a toner image,
• a toner supplying roller that supplies the toner to the developing roller,
• a toner regulating member that regulates a layer thickness of the toner on the developing roller, and
• a toner,
• a surface of the developing roller is in contact with a surface of the toner supplying roller, a movement direction of the surface of the developing roller is opposite to a movement direction of the surface of the toner supplying roller in a position where the surface of the developing roller is in contact with the surface of the toner supplying roller,
• the movement direction of the surface of the toner supplying roller includes an upward component at the position where the surface of the developing roller is in contact with the surface of the toner supplying roller in a mounting state where the process cartridge is mounted on an apparatus main body of the image forming apparatus,
• a toner flow path formed of an inner wall of the developing chamber and the surface of the toner supplying roller is formed upstream of the toner supplying roller in a rotation direction with respect to the position where the developing roller is in contact with the toner supplying roller in a cross section of the process cartridge in a direction perpendicular to a rotation axial line of the toner supplying roller, a closest distance between the inner wall of the developing chamber and the surface of the toner supplying roller in the toner flow path is 1.0 mm or greater and 5.0 mm or less,
• the developing roller and the toner supplying roller are formed such that a peripheral speed ratio R represented by Equation (E1) satisfies
• 1.1
• ≤
• R
• ≤
• 2.5
• ,
• R
• =
• V
• RS
• /
• V
• D
• (
• E
• ⁢
• 1
• )
• (in Equation (E1), VRs represents an absolute value [m/sec] of a peripheral speed of the surface of the toner supplying roller, and Vp represents an absolute value [m/sec] of a peripheral speed of the surface of the developing roller),
• the toner contains a toner particle and a silica particle,
• the toner has a number average particle diameter of 4.0 μm or greater and 9.0 μm or less,
• the toner has an average circularity of 0.955 or greater and 0.975 or less,
• a proportion of the particle having a circularity of 0.900 or greater and 0.930 or less in a circularity distribution of the toner is 2.0% by number or greater and 15.0% by number or less,
• a content of the silica particle is 1.5 parts by mass or greater and 5.0 parts by mass or less with respect to 100 parts by mass of the toner particle, and
• a sticking ratio of the silica particle to the toner particle, which is measured by a water washing method, is 70% or greater and 82% or less.