BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure is directed to an electrophotographic apparatus, a process cartridge, and a cartridge set.

Description of the Related Art

In recent years, electrophotographic apparatuses such as copiers, printers, and so forth are required to realize greater energy savings. As a consequence, the development of a toner capable of being fixed at lower temperatures has also been going forward within the toner realm.

Japanese Patent Application Laid-open No. 2017-211648 discloses a toner that exhibits an enhanced low-temperature plasticity brought about by the use of crystalline polyester. Japanese Patent Application Laid-open No. 2017-211648 states that so-called cold offset—in which, due to an insufficient melting of a toner, the toner attaches onto a fixing film during passage through a fixing nip and, after a single rotation in this condition, fixing onto the paper is implemented—can be suppressed. Japanese Patent Application Laid-open No. 2017-211648 also states that a sharp melt property can be enhanced by dispersing such a crystalline material in the form of microfine domains in the toner.

In Japanese Patent Application Laid-open No. 2017-207680, through the combination of domain control of a crystalline polyester and a low-melting wax, both the low-temperature fixability brought about by a sharp melt property and the storability at high temperatures can be implemented.

SUMMARY OF THE INVENTION

When image formation is carried out at a high process speed, the frequency with which untransferred toner slips past a cleaning blade increases and then an amount of untransferred toner coming into contact with a charging member tends to increase.

On the other hand, the toners according to Japanese Patent Application Laid-open Nos. 2017-211648 and 2017-207680, which exhibit excellent low-temperature fixabilities, readily undergo deformation, for example, when used in a high-temperature, high-humidity environment.

As a consequence, when, in a high-temperature, high-humidity environment, these toners, which exhibit excellent low-temperature fixabilities, become attached, as untransferred toner, to the surface of the charging member, this untransferred toner melt-adheres to the surface of the charging member and may form a film of fused toner material on the surface of the charging member. It has been found that a charging member having on an outer surface thereof such a fused material film cannot uniformly charge the electrophotographic photosensitive member and may cause non-uniformity in an image.

For example, one method for suppressing toner deformation, as in Japanese Patent Application Laid-open No. 2003-280246, is to improve the viscoelasticity of the toner using, for example, a crosslinking agent. However, the fixation temperature of such a toner becomes relatively high. That is, the inhibition of toner deformation resides in a trade-off relationship with an excellent low-temperature fixability.

The present disclosure provides an electrophotographic apparatus, a process cartridge, and a cartridge set that exhibit an excellent energy-savings performance and are able to form a high-quality electrophotographic image in a stable manner.

One aspect of the present disclosure provides an electrophotographic apparatus comprising:an electrophotographic photosensitive member,a charging unit for charging a surface of the electrophotographic photosensitive member, anda developing unit for developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a toner to form a toner image on the surface of the electrophotographic photosensitive member electrophotographic photosensitive member, wherein

the charging unit comprises a conductive member disposed to be contactable with the electrophotographic photosensitive member,

the conductive member comprises:a support having a conductive outer surface, anda conductive layer disposed on the outer surface of the support,

the conductive layer comprises:a matrix, anda plurality of domains dispersed in the matrix,

the matrix contains a first rubber,

each of the domains contains a second rubber and an electronic conductive agent,

at least a portion of the domains is exposed at the outer surface of the conductive member,

the outer surface of the conductive member is constituted of at least the matrix and the domains that are exposed at the outer surface of the conductive member,

the matrix has a volume resistivity R1 of greater than 1.00×1012Ω·cm,

a volume resistivity R2 of the domains is smaller than the volume resistivity R1 of the matrix,

when G1 is Martens hardness measured on the matrix that is exposed at the outer surface of the conductive member, and G2 is Martens hardness measured on the domains that are exposed at the outer surface of the conductive member, G1 and G2 are both within a range from 1.0 N/mm2to 10.0 N/mm2, and satisfy relationship G1<G2,

the developing unit contains the toner,

the toner has a toner particle that contains a binder resin, a colorant, and a crystalline material, and

the toner has an onset temperature T(A) of not more than 80.0° C., T(A) being an onset temperature of the storage elastic modulus E′ according to powder dynamic viscoelastic measurement.

Another aspect of the present disclosure provides a process cartridge disposed detachably to a main body of an electrophotographic apparatus, wherein

the process cartridge comprises

a charging unit for charging a surface of an electrophotographic photosensitive member, and

a developing unit for developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a toner to form a toner image on the surface of the electrophotographic photosensitive member,

the charging unit comprises a conductive member disposed to be contactable with the electrophotographic photosensitive member,

the conductive member comprises:a support having a conductive outer surface, anda conductive layer disposed on the outer surface of the support,

the conductive layer comprises:a matrix, anda plurality of domains dispersed in the matrix,

the matrix contains a first rubber,

each of the domains contains a second rubber and an electronic conductive agent,

at least a portion of the domains is exposed at the outer surface of the conductive member,

the outer surface of the conductive member is constituted of at least the matrix and the domains that are exposed at the outer surface of the conductive member,

the matrix has a volume resistivity R1 of greater than 1.00×1012Ω·cm,

a volume resistivity R2 of the domains is smaller than the volume resistivity R1 of the matrix,

when G1 is Martens hardness measured on the matrix that is exposed at the outer surface of the conductive member and G2 is Martens hardness measured on the domains that are exposed at the outer surface of the conductive member, G1 and G2 are both within a range from 1.0 N/mm2to 10.0 N/mm2and satisfy relationship G1<G2,

the developing unit contains the toner,

the toner has a toner particle that contains a binder resin, a colorant, and a crystalline material, and

the toner has an onset temperature T(A) of not more than 80.0° C., T(A) being an onset temperature of a storage elastic modulus E′ according to powder dynamic viscoelastic measurement.

Another aspect of the present disclosure provides a cartridge set having a first cartridge and a second cartridge that are disposed detachably to a main body of an electrophotographic apparatus, wherein

the first cartridge has a charging unit for charging a surface of an electrophotographic photosensitive member and has a first frame for supporting the charging unit,

the second cartridge has a toner container that accommodates a toner for forming a toner image on the surface of the electrophotographic photosensitive member by developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member,

the charging unit comprises a conductive member disposed to be contactable with the electrophotographic photosensitive member,

the conductive member comprises:a support having a conductive outer surface, anda conductive layer disposed on the outer surface of the support,

the conductive layer comprises:a matrix, anda plurality of domains dispersed in the matrix,

the matrix contains a first rubber,

each of the domains contains a second rubber and an electronic conductive agent,

at least a portion of the domains are exposed at the outer surface of the conductive member,

the outer surface of the conductive member is constituted of at least the matrix and the domains that are exposed at the outer surface of the conductive member,

the matrix has a volume resistivity R1 of greater than 1.00×1012Ω·cm,

a volume resistivity R2 of the domains is smaller than the volume resistivity R1 of the matrix,

when G1 is Martens hardness measured on the matrix that is exposed at the outer surface of the conductive member and G2 is Martens hardness measured on the domains that are exposed at the outer surface of the conductive member, G1 and G2 are both within a range from 1.0 N/mm2to 10.0 N/mm2and satisfy relationship G1<G2,

the toner has a toner particle that contains a binder resin, a colorant, and a crystalline material, and

the toner has an onset temperature T(A) of not more than 80.0° C., T(A) being an onset temperature of a storage elastic modulus E′ according to powder dynamic viscoelastic measurement.

The present disclosure can provide an electrophotographic apparatus, a process cartridge, and a cartridge set that exhibit an excellent energy-savings performance and are able to form a high-quality electrophotographic image in a stable manner.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

