Electrophotographic photosensitive member, process cartridge and electrophotographic apparatus
The electrophotographic photosensitive member has: a cylindrical support; a charge generating layer formed on the cylindrical support; and a charge transport layer formed on the charge generating layer, the charge generating layer contains a hydroxygallium phthalocyanine crystal having a particular CuKα characteristic X-ray diffraction peak, a titanyl phthalocyanine crystal having a particular CuKα characteristic X-ray diffraction peak or a chlorogallium phthalocyanine crystal having a particular spectral absorption spectrum as a charge generating material, and in the charge generating layer, with respect to the film thickness of the charge generating layer, when a region from the central position of an image forming area to the end position of the image forming area is divided in the axial direction of the cylindrical support into five equal regions and the average film thickness of the charge generating layer in each region satisfies a specific condition.
1. An electrophotographic photosensitive member, comprising in this order:
a cylindrical support;
a conductive layer that contains a binder resin and a metal oxide fine particle, the metal oxide fine particle having a core material containing titanium oxide and an enveloping layer covering the core material that contains niobium or tantalum-doped titanium oxide;
a charge generating layer that contains a hydroxygallium phthalocyanine crystal as a charge generating material, the hydroxygallium phthalocyanine crystal having strong peaks at Bragg angle 2θ of 7.4°±0.3° and 28.2°±0.3° in CuKα characteristic X-ray diffraction; and
a charge transport layer, wherein
d 1 <d 2 <d 3 <d 4 <d 5 where in the charge generating layer, when a region from a central position of an image forming area to an end position of the image forming area is divided in an axial direction of the cylindrical support into five equal regions, d 1 , d 2 , d 3 , d 4 and d 5 are respectively average film thicknesses of the charge generating layer in each region in order from the central part,
the hydroxygallium phthalocyanine crystal contains 0.4 to 3.0% by mass of a compound having a structure represented by formula (A1)
where R 0 represents a methyl group, a propyl group or a vinyl group,
1
-
e
-
2
β
d
6
1
-
e
-
2
β
d
0
≥
1.2
(
E
1
)
where β (nm −1 ) is an absorption coefficient of the charge generating layer, d 0 is a film thickness of the charge generating layer at the central position of the image forming area and d 6 is a film thickness of the charge generating layer at the end position of the image forming area, and
a film thickness of the charge generating layer for all Y, where 0≤Y≤Y max , is between d−0.2Δ and d+0.2Δ with respect to d=d(Y) calculated with expression (E2)
d
(
Y
)
=
d
0
+
Δ
(
1
-
βΔ
)
Y
2
Y
max
2
+
βΔ
2
Y
4
Y
max
4
(
E
2
)
where Y (mm) is a distance in the charge generating layer from the central position of the image forming area in the axial direction of the cylindrical support, Y max is a value of Y at the end position of the image forming area, and Δ=d 6 −d 0 .
2. The electrophotographic photosensitive member according to claim 1 , wherein the conductive layer has a film thickness of greater than 10 μm.
3. A process cartridge integrally supporting an electrophotographic photosensitive member and at least one unit selected from the group consisting of a charging unit, a developing unit and a cleaning unit, the process cartridge being removably attached to a main body of an electrophotographic apparatus, the electrophotographic photosensitive member comprising in this order:
a cylindrical support;
a conductive layer that contains a binder resin and a metal oxide fine particle, the metal oxide fine particle having a core material containing titanium oxide and an enveloping layer covering the core material that contains niobium or tantalum-doped titanium oxide;
a charge generating layer that contains a hydroxygallium phthalocyanine crystal as a charge generating material, the hydroxygallium phthalocyanine crystal having strong peaks at Bragg angle 2θ of 7.4°±0.3° and 28.2°±0.3° in CuKα characteristic X-ray diffraction; and
a charge transport layer, wherein
d 1 <d 2 <d 3 <d 4 <d 5 where in the charge generating layer, when a region from a central position of an image forming area to an end position of the image forming area is divided in an axial direction of the cylindrical support into five equal regions, d 1 , d 2 , d 3 , d 4 and d 5 are respectively average film thicknesses of the charge generating layer in each region in order from the central part,
the hydroxygallium phthalocyanine crystal contains 0.4 to 3.0% by mass of a compound having a structure represented by formula (A1)
where R 0 represents a methyl group, a propyl group or a vinyl group,
1
-
e
-
2
β
d
6
1
-
e
-
2
β
d
0
≥
1.2
(
E
1
)
where β (nm −1 ) is an absorption coefficient of the charge generating layer, d 0 is a film thickness of the charge generating layer at the central position of the image forming area and d 6 is a film thickness of the charge generating layer at the end position of the image forming area, and
a film thickness of the charge generating layer for all Y, where 0≤Y≤Y max , is between d−0.2Δ and d+0.2Δ with respect to d=d(Y) calculated with expression (E2)
d
(
Y
)
=
d
0
+
Δ
(
1
-
βΔ
)
Y
2
Y
max
2
+
βΔ
2
Y
4
Y
max
4
(
E
2
)
where Y (mm) is a distance in the charge generating layer from the central position of the image forming area in the axial direction of the cylindrical support, Y max is a value of Y at the end position of the image forming area, and Δ=d 6 −d 0 .
4. The process cartridge according to claim 3 , wherein the conductive layer has a film thickness of greater than 10 μm.
5. An electrophotographic apparatus having an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit and a transfer unit, the electrophotographic photosensitive member comprising in this order:
a cylindrical support;
a conductive layer that contains a binder resin and a metal oxide fine particle, the metal oxide fine particle having a core material containing titanium oxide and an enveloping layer covering the core material that contains niobium or tantalum-doped titanium oxide;
a charge generating layer that contains a hydroxygallium phthalocyanine crystal as a charge generating material, the hydroxygallium phthalocyanine crystal having strong peaks at Bragg angle 2θ of 7.4°±0.3° and 28.2°±0.3° in CuKα characteristic X-ray diffraction; and
a charge transport layer, wherein
d 1 <d 2 <d 3 <d 4 <d 5 where in the charge generating layer, when a region from a central position of an image forming area to an end position of the image forming area is divided in an axial direction of the cylindrical support into five equal regions, d 1 , d 2 , d 3 , d 4 and d 5 are respectively average film thicknesses of the charge generating layer in each region in order from the central part,
the hydroxygallium phthalocyanine crystal contains 0.4 to 3.0% by mass of a compound having a structure represented by formula (A1)
where R 0 represents a methyl group, a propyl group or a vinyl group,
1
-
e
-
2
β
d
6
1
-
e
-
2
β
d
0
≥
1.2
(
E
1
)
where β (nm −1 ) is an absorption coefficient of the charge generating layer, d 0 is a film thickness of the charge generating layer at the central position of the image forming area and d 6 is a film thickness of the charge generating layer at the end position of the image forming area, and
a film thickness of the charge generating layer for all Y, where 0≤Y≤Y max , is between d−0.2Δ and d+0.2Δ with respect to d=d(Y) calculated with expression (E2)
d
(
Y
)
=
d
0
+
Δ
(
1
-
βΔ
)
Y
2
Y
max
2
+
βΔ
2
Y
4
Y
max
4
(
E
2
)
where Y (mm) is a distance in the charge generating layer from the central position of the image forming area in the axial direction of the cylindrical support, Y max is a value of Y at the end position of the image forming area, and Δ=d 6 −d 0 .
6. The electrophotographic apparatus according to claim 5 ,
wherein the conductive layer has a film thickness of greater than 10 μm.