JP2015011131A5 - - Google Patents

Claims (8)

In a process cartridge detachable from the main body of the image forming apparatus,
The process cartridge is
An electrostatic latent image carrier;
A charging member for charging the electrostatic latent image carrier;
Developing means for developing the electrostatic latent image formed on the surface of the electrostatic latent image carrier using toner;
Have
The charging member is a charging member having a conductive substrate and a conductive surface layer,
The surface layer of the charging member is
Binder resin C;
Conductive particles dispersed in the binder resin C;
Resin particles roughening the surface layer;
Including
The surface layer of the charging member has a plurality of convex portions derived from the resin particles on the surface,
The resin particles forming the convex portion have pores inside thereof,
The porosity Vt of the entire resin particle is 2.5% by volume or less,
Assuming that the resin particles are solid particles having no voids, the voids in a region that occupies 11% by volume in the solid particles and that is farthest from the conductive substrate the rate _{V 11} is, is 20 vol% 5 vol% or more,
The toner is a toner particle containing a binder resin T and a colorant, and a toner containing silica fine particles as an external additive,
The coverage X1 with the silica fine particles on the toner surface determined by an X-ray photoelectron spectrometer (ESCA) is 40.0 area% or more and 75.0 area% or less,
When the theoretical coverage by the silica fine particles is X2, the diffusion index represented by the following formula 1 satisfies the following formula 2. (Formula 1) Diffusion index = X1 / X2
(Expression 2) Diffusion index ≧ −0.0042 × X1 + 0.62
A process cartridge characterized by that.   The process cartridge according to claim 1, wherein the toner particles have an average circularity of 0.960 or more. The toner further contains strontium titanate fine particles as an external additive,
The process cartridge according to claim 1 or 2, wherein the number average particle diameter (D1) of primary particles of the strontium titanate fine particles is 60 nm or more and 200 nm or less.   4. The process cartridge according to claim 1, wherein an embedding rate of the external additive in the toner particles is 25% or more and 60% or less.   The process cartridge according to any one of claims 1 to 4, wherein a release rate of the strontium titanate fine particles is 20% or more and 70% or less. The silica fine particles are treated with 15.0 parts by mass or more and 40.0 parts by mass or less of silicone oil based on 100 parts by mass of the silica fine particle base.
The process cartridge according to any one of claims 1 to 5, wherein an immobilization rate (%) based on carbon amount of the silicone oil is 70% or more.   The process cartridge according to claim 1, wherein an apparent density of the silica fine particles is 15 g / L or more and 50 g / L or less. The process cartridge according to claim 1, wherein the silica fine particle base has a BET specific surface area of 130 m ² / g or more and 330 m ² / g or less.