Process cartridge and image forming apparatus
A charging member that contacts an image bearing member and charges the image bearing member has an electrically conductive support and an elastic layer in contact with the image bearing member. The elastic layer includes a semiconductive rubber composition including a matrix and domains having electric conductivity. The semiconductive rubber composition has a sea-island structure in which the domains form an island phase and the matrix forms a sea phase. The matrix has a higher volume resistivity than the domains. The developer includes a toner, and the toner has a Martens hardness of at least 200 MPa and not more than 1100 MPa when measured under a maximum load of 2.0×10 −4 N.
1. A process cartridge for use in an image forming apparatus, comprising:
an image bearing member;
a charging member configured to contact the image bearing member and charge the image bearing member;
a developer bearing member configured to contact the image bearing member and bear a developer for developing a latent image formed on the charged image bearing member;
wherein,
the charging member has an electrically conductive support and an elastic layer in contact with the image bearing member;
the elastic layer includes a semiconductive rubber composition including a matrix and domains having electric conductivity;
the semiconductive rubber composition has a sea-island structure in which the domains form an island phase and the matrix forms a sea phase;
the matrix has a higher volume resistivity than the domain;
the developer includes a toner; and
the toner has a Martens hardness of at least 200 MPa and not more than 1100 MPa when measured under a maximum load of 2.0×10 −4 N.
2. The process cartridge according to claim 1 , wherein the toner has a Martens hardness of at least 5 MPa and not more than 100 MPa when measured under a maximum load of 9.8×10 −4 N.
3. The process cartridge according to claim 1 , wherein
the toner has a toner particle;
the toner particle has a surface layer including an organosilicon polymer; and
an average number of carbon atoms directly bonded to a silicon atom in the organosilicon polymer is at least 1 and not more than 3 per one silicon atom.
4. The process cartridge according to claim 3 , wherein the organosilicon polymer has a structure represented by a following formula (1):
R—SiO 3/2 Formula (1)
wherein R represents a hydrocarbon group having at least 1 and not more than 6 carbon atoms.
5. The process cartridge according to claim 4 , wherein
R as defined above is a hydrocarbon group having at least 1 and not more than 3 carbon atoms.
6. The process cartridge according to claim 1 , wherein
the domains include an electrically conductive particle.
7. The process cartridge according to claim 1 , wherein
a circumferential surface of the elastic layer that is in contact with the image bearing member is configured such that portions made of the domains are scattered on a surface composed of the matrix.
8. An image forming apparatus comprising:
an apparatus main body; and
the process cartridge according to claim 1 that is detachably attachable to the apparatus main body.