Electrophotographic apparatus and process cartridge
The electrophotographic apparatus and process cartridge comprising an electrophotographic photosensitive member, a cleaning blade, and developing unit containing a toner, wherein the cleaning blade comprising a support member and an elastic member whose portion is abutting a surface of the electrophotographic photosensitive member; the elastic member has an elastic modulus of 15 to 470 MPa with coefficient of variation for the elastic modulus being not more than 7.0%, and the absolute value of a difference between Martens hardness values is not more than 0.30 N/mm 2 as measured under prescribed conditions; the toner contains a toner particle and an external additive whose a number-average primary particle diameter is from 5 to 25 nm, when X1 is a coverage ratio of the toner particle by the external additive and X2 is a theoretical coverage ratio, X1 is 50 to 85 area %, and X1/X2≥−0.0042×X1+0.60 is satisfied.
1. An electrophotographic apparatus comprising:
an electrophotographic photosensitive member having a support and a photosensitive layer on the support;
charging unit for charging a surface of the electrophotographic photosensitive member;
exposing unit for forming a latent image on the surface of the electrophotographic photosensitive member, by irradiating the surface of the electrophotographic photosensitive member with exposing light;
developing unit containing a toner and for forming a toner image on the surface of the electrophotographic photosensitive member by developing the latent image with the toner;
transferring unit for transferring the toner image on the surface of the electrophotographic photosensitive member to a transfer material; and
a cleaning blade,
wherein
the cleaning blade comprises
a polyurethane-containing elastic member, and
a support member that supports the elastic member,
the cleaning blade is disposed so that a portion of the elastic member is in contact with the surface of the electrophotographic photosensitive member;
when a side of the elastic member in contact with the surface of the electrophotographic photosensitive member is defined as a tip side of the elastic member, the elastic member has a plate shape at least at the tip side, the plate shape having a main surface and a tip surface that forms a tip side edge in combination with the main surface, the main surface facing the surface of the electrophotographic photosensitive member;
assuming that, on the tip surface, a hypothetical first line segment in parallel to the tip side edge at a distance of 10 μm from the tip side edge and having the same length as the tip side edge is drawn, designating a length of the first line segment as L, and defining, in the first line segment,
P1 to be a point that is (1/10)L from one end of the first line segment,
P2 to be a point that is (2/10)L from the one end of the first line segment,
P3 to be a point that is (3/10)L from the one end of the first line segment,
P4 to be a point that is (4/10)L from the one end of the first line segment,
P5 to be a point that is (5/10)L from the one end of the first line segment,
P6 to be a point that is (6/10)L from the one end of the first line segment,
P7 to be a point that is (7/10)L from the one end of the first line segment,
P8 to be a point that is (8/10)L from the one end of the first line segment, and
P9 to be a point that is (9/10)L from the one end of the first line segment, and
designating, on the first line segment, a total of 630 points comprising, centered on each of P1 to P9, 70 points at each of the P1 to P9 on a 1 μm pitch, an average value of elastic modulus values obtained by measurement at each of locations of the 630 points using a scanning probe microscope is from 15 MPa to 470 MPa and coefficient of variation for the elastic modulus is not more than 7.0%;
|HM1−HM2|≤0.30 N/mm 2 where HM1 is Martens hardness of the elastic member measured at the location of P5 and HM2 is Martens hardness of the elastic member measured at the location that is a distance of 500 μm from the tip side edge on a bisector that is provided on supposition that a hypothetical bisector of an angle made between the main surface and the tip surface is drawn in a cross section of the elastic member that is orthogonal to the tip side edge and the tip surface that contains P5,
the toner comprises a toner particle and an external additive,
the external additive has a number-average primary particle diameter of 5 to 25 nm,
when a coverage ratio on a surface of the toner particle by the external additive, as measured with an X-ray photoelectron spectrometer, is defined as X1, the X1 is from 50 to 85 area %, and
when a theoretical coverage ratio on the surface of the toner particle by the external additive is defined as X2, a spreading index given by formula (1) below satisfies formula (2) below:
(1) spreading index= X 1/ X 2
(2) spreading index≥−0.0042× X 1+0.60.
2. The electrophotographic apparatus according to claim 1 , wherein the external additive comprises silica fine particles.
3. The electrophotographic apparatus according to claim 1 , wherein the X1 is from 60 to 80 area %.
4. The electrophotographic apparatus according to claim 1 , wherein the |HM1−HM2| is not more than 0.10 N/mm 2 .
5. The electrophotographic apparatus according to claim 1 , wherein when an immobilization percentage of the external additive relative to the toner particle is defined as F, the F is at least 75%.
6. The electrophotographic apparatus according to claim 1 , wherein the external additive further comprises a hydrotalcite compound.
7. The electrophotographic apparatus according to claim 1 , wherein
the spreading index is 0.51 to 0.56, and
a value of −0.0042×X1+0.60 is 0.25 to 0.35.
8. A process cartridge detachably disposed in an apparatus main body of an electrophotographic apparatus, the process cartridge comprising:
an electrophotographic photosensitive member having a support and a photosensitive layer on the support;
a developing unit containing a toner and for forming a toner image on a surface of the electrophotographic photosensitive member by developing a latent image formed on the surface of the electrophotographic photosensitive member with the toner; and
a cleaning blade,
wherein
the cleaning blade comprises
a polyurethane-containing elastic member, and
a support member that supports the elastic member,
the cleaning blade is disposed so that a portion of the elastic member is in contact with the surface of the electrophotographic photosensitive member,
when a side of the elastic member in contact with the surface of the electrophotographic photosensitive member is defined as a tip side of the elastic member the elastic member has a plate shape at least at said tip side, the plate shape having a main surface and a tip surface that forms a tip side edge in combination with the main surface, the main surface facing the surface of the electrophotographic photosensitive member;
assuming that, on the tip surface, a hypothetical first line segment in parallel to the tip side edge at a distance of 10 μm from the tip side edge and having the same length as the tip side edge is drawn, designating a length of the first line segment as L, and defining, in the first line segment,
P1 to be a point that is (1/10)L from one end of the first line segment,
P2 to be a point that is (2/10)L from the one end of the first line segment,
P3 to be a point that is (3/10)L from the one end of the first line segment,
P4 to be a point that is (4/10)L from the one end of the first line segment,
P5 to be a point that is (5/10)L from the one end of the first line segment,
P6 to be a point that is (6/10)L from the one end of the first line segment,
P7 to be a point that is (7/10)L from the one end of the first line segment,
P8 to be a point that is (8/10)L from the one end of the first line segment, and
P9 to be a point that is (9/10)L from the one end of the first line segment, and
designating, on the first line segment, a total of 630 points comprising, centered on each of P1 to P9, of 70 points at each of the P1 to P9 on a 1 μm pitch, an average value of elastic modulus values obtained by measurement at each of locations of the 630 points using a scanning probe microscope is from 15 MPa to 470 MPa and coefficient of variation for the elastic modulus is not more than 7.0%,
|HM1−HM2|≤0.30 N/mm 2 where HM1 is Martens hardness of the elastic member measured at the location of P5 and HM2 is Martens hardness of the elastic member measured at the location that is a distance of 500 μm from the tip side edge on a bisector that is provided on supposition that a hypothetical bisector of an angle made between the main surface and the tip surface is drawn in a cross section of the elastic member that is orthogonal to the tip side edge and the tip surface that contains P5,
the toner comprises a toner particle and an external additive,
the external additive has a number-average primary particle diameter of 5 to 25 nm;
when a coverage ratio on a surface of the toner particle by the external additive, as measured with an X-ray photoelectron spectrometer, is defined as X1, the X1 is from 50 to 85 area %, and
when a theoretical coverage ratio on the surface of the toner particle by the external additive is defined as X2, a spreading index given by formula (1) below satisfies formula (2) below:
(1) spreading index= X 1/ X 2
(2) spreading index≥−0.0042× X 1+0.60.