JP2020101693A - Cleaning device, process cartridge, and image forming apparatus - Google Patents

Abstract

To satisfactorily remove a toner on an image carrier with a cleaning member.SOLUTION: A cleaning device comprises: a cleaning frame body; a cleaning member that is attached to the cleaning frame body at one end and has a free end at the other end, the cleaning member in contact with an image carrier that carries a developer image formed of a developer and is rotatable, and removes the developer remaining on the image carrier after the developer image is transferred from the image carrier; and a sheet member that is attached to the cleaning frame body at one end, and is in contact with the image carrier at the other end at a position on the upstream side of a contact position of the cleaning member and the image carrier in the direction of rotation of the image carrier. The work function W(D) of the developer and the work function W(S) of the sheet member satisfy 0≤W(D)-W(S)≤0.23; the developer includes inorganic fine particles, and at least one type of the inorganic fine particles have an average primary particle diameter of 50 nm or more.SELECTED DRAWING: Figure 5

Description

The present invention relates to a cleaning device, a process cartridge, and an image forming apparatus that remove a developer remaining on a photoconductor after transferring a developer image from an electrophotographic photoconductor to a recording medium.

Conventionally, in an image forming apparatus such as a copying machine or a printer, an electrostatic recording method or an electrophotographic recording method has been widely used. In this image forming apparatus, an electrostatic latent image is formed on a photoconductor, and then this developer image is transferred to a recording material to form an image. In such an image forming apparatus, since the untransferred developer remains on the photosensitive drum after the transfer, the developer is usually removed by a cleaning device using an elastic blade or the like. Further, in recent years, in order to improve image quality such as high definition, a developer (toner) having a small average particle diameter tends to be used.
However, the toner having a small particle size cannot be sufficiently removed by a conventional cleaning device using an elastic blade or the like, and the amount of toner passing through between the elastic blade and the photoconductor increases, which may result in cleaning failure. Therefore, in the image forming apparatus disclosed in Japanese Patent Laid-Open No. 2004-242242, a charger that removes residual toner that has not been transferred is disposed between the cleaning unit and the transfer unit that transfers the developer to the recording material.

JP, 6-130870, A

In Patent Document 1, since the charger is used in the image forming apparatus, the cost is increased, and a space such as the charger and the high voltage output device is required, and the size of the image forming apparatus is increased. Further, in Japanese Patent Application Laid-Open No. 2004-163242, in the residual toner neutralization step, only the surface of the toner surface facing the neutralization device is neutralized, and the surface in contact with the photoconductor is not sufficiently neutralized. Happens. Therefore, the residual toner such as a toner having a high charge amount or a toner having a small particle size has a large electrostatic adhesion force to the drum surface, and the static eliminator does not eliminate the static electricity on the surface adhering to the photoconductor. Therefore, it is difficult to remove the residual toner, which may result in a defective image. Further, when a polymerized toner having a high degree of circularity is used, it is difficult to scrape it off with a cleaning blade, and the toner easily slips through the cleaning blade, resulting in a defective image.

The present invention has been made in view of the above problems, and an object of the present invention is to satisfactorily remove toner on an image bearing member with a cleaning member.

In order to achieve the above object, the cleaning device of the present invention,
A cleaning frame,
A cleaning member, one end of which is attached to the cleaning frame and the other end of which is a free end, carries a developer image made of a developer and is in contact with a rotatable image carrier. A cleaning member for removing the developer remaining on the image carrier after the developer image is transferred,
One end is attached to the cleaning frame, and the other end contacts the image carrier at a position upstream of the contact position between the cleaning member and the image carrier in the rotation direction of the image carrier, and A sheet member having slidability,
A cleaning device having:
The work function W(D) of the developer and the work function W(S) of the sheet member satisfy the following formula (A), and the developer has inorganic fine particles, and at least the inorganic fine particles are included. One kind of average primary particle diameter is 50 nm or more.
0≦W(D)−W(S)≦0.23 (A)
In order to achieve the above object, the process cartridge of the present invention is
An image bearing member that holds a developer image made of a developer and is rotatable;
A cleaning frame,
A cleaning member, one end of which is attached to the cleaning frame and the other end of which is a free end, contacts the image carrier, and after the developer image is transferred from the image carrier to the image carrier. A cleaning member for removing the remaining developer,
One end is attached to the cleaning frame, and the other end contacts the image carrier at a position upstream of the contact position between the cleaning member and the image carrier in the rotation direction of the image carrier, and A sheet member having slidability,
A process cartridge having
The work function W(D) of the developer and the work function W(S) of the sheet member satisfy the following formula (A), and the developer has inorganic fine particles, and at least the inorganic fine particles are included. One kind of average primary particle diameter is 50 nm or more.
0≦W(D)−W(S)≦0.23 (A)
In order to achieve the above object, the image forming apparatus of the present invention,
An image bearing member that holds a developer image made of a developer and is rotatable;
A transfer member for transferring the developer image to a recording material,
A cleaning frame,
A cleaning member, one end of which is attached to the cleaning frame and the other end of which is a free end, is in contact with the image carrier, and after the developer image is transferred from the image carrier to the image carrier. A cleaning member for removing the residual developer,
One end is attached to the cleaning frame, and the other end contacts the image carrier at a position upstream of the contact position between the cleaning member and the image carrier in the rotation direction of the image carrier, and A sheet member having slidability,
An image forming apparatus having:
The work function W(D) of the developer and the work function W(S) of the sheet member satisfy the following formula (A), and the developer has inorganic fine particles, and at least the inorganic fine particles are included. One kind of average primary particle diameter is 50 nm or more.
0≦W(D)−W(S)≦0.23 (A)

According to the present invention, the cleaning member can favorably remove the toner on the image carrier.

Schematic cross-sectional view of an image forming apparatus according to the present invention Schematic sectional view of a process cartridge according to the present invention Explanatory drawing of the penetration amount and set angle of the recovery sheet member according to the present invention Explanatory drawing of the calculation method of the contact pressure of the recovery sheet member which concerns on this invention. Graph showing the measurement results of the work function of the recovery sheet member and the toner according to the present invention Graph showing the toner charge amount of Example 1 and Comparative Example 4 according to the present invention 3 is a graph showing toner charge amounts of Example 1 and Example 5 according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment)
<Overview of the image forming apparatus>
An image forming process of the image forming apparatus used in the embodiment will be described with reference to FIG. 1 together with members included in the image forming apparatus. A recording material (sheet) P such as paper is conveyed from a sheet cassette 12 of an image forming apparatus main body A included in the image forming apparatus by a conveying roller (not shown), and a rotatable image carrier is synchronized with the conveyance of the recording material P. The photosensitive drum 1 as a body is charged by a charging roller 2 as a rotatable charging unit. Thereafter, the exposure device 3 selectively exposes the photosensitive drum 1 to form an electrostatic latent image on the photosensitive drum 1. The photosensitive drum 1 and the charging roller 2 are rotating bodies, the photosensitive drum 1 rotates in the direction of arrow R1, and the charging roller 2 rotates in the direction of arrow R2. The laser emitted from the exposure device 3 is reflected by the polygon mirror 17, so that the surface of the photosensitive drum 1 is exposed in the main scanning direction and the sub scanning direction.

The magnetic one-component developer T (hereinafter, also referred to as a toner) contained in the developer accommodating chamber 4 is supplied to a developer carrier (hereinafter referred to as a developing sleeve) 6 by a stirring member 5. The developing sleeve 6 is a hollow rotating body and has a magnet roller (not shown) as a conveying member inside. The toner is carried and conveyed on the surface of the developing sleeve 6 by the magnetic force of the magnet roller. Further, a desired amount of the magnetic one-component developer T is carried in a thin layer on the surface of the developing sleeve 6 by the developing blade 7.
Next, by applying a developing bias to the developing sleeve 6, toner is supplied to the photosensitive drum 1, and a toner image (developer image) corresponding to the latent image on the photosensitive drum 1 is developed. Therefore, the photosensitive drum 1 carries a toner image made of toner. The developer image is transferred to the conveyed recording material P by applying a bias to the transfer roller 10 as a transfer member. The recording material P is conveyed to the fixing device 11, the toner image is fixed on the recording material P, and the recording material P is discharged to the paper discharge unit 13 above the image forming apparatus by a paper discharge roller (not shown).
After the transfer is completed, the toner (transfer residual toner) remains on the photosensitive drum 1. The toner on the photosensitive drum 1 is removed by a cleaning member (cleaning blade) 8 having elasticity. The removed toner is stored in a recovery container (accommodation container) 9 that is a storage unit. The collecting sheet member (sheet member) 14 as a sealing member prevents the toner contained in the collecting container 9 from leaking to the outside.

<Process cartridge>
Next, the overall structure of the process cartridge B will be described with reference to FIG. The process cartridge B has a photosensitive unit 21 having the photosensitive drum 1 and the like, and a developing unit (developing device) 20 having the developing sleeve 6 and the like. The photoconductor unit 21 includes a cleaning device 22 that removes residual toner remaining on the photoconductor drum 1 and the photoconductor drum 1. The cleaning device 22 includes a charging roller 2, a cleaning member 8, a collection container 9, a collection sheet member 14 as a collection member, and a frame body (cleaning frame body) 15 of the collection container 9. When the cleaning member 8 contacts the photosensitive drum 1, the toner remaining on the surface of the photosensitive drum 1 is removed.
The photosensitive drum 1 is rotatably attached to the photosensitive unit 21 via a bearing (not shown). The photosensitive drum 1 is rotationally driven in the direction of arrow R1 in FIG. 2 according to an image forming operation by receiving the driving force of a drive motor (not shown). Further, the photoconductor unit 21 includes the charging roller 2, the cleaning member 8, the collecting sheet member 14, and the collecting container 9. The charging roller 2, the cleaning member 8, and the recovery sheet member 14 are arranged so as to contact the photosensitive drum 1, respectively.

The photosensitive drum 1 has a diameter of 24 mm and includes a charge transport layer, a charge generation layer, an undercoat layer, and an aluminum cylinder. The rotation speed of the photosensitive drum 1 is, for example, 200 mm/sec.
The charging roller 2 is made of a conductive sponge-like rubber material and is urged by an urging spring (not shown) to roll on the surface of the photosensitive drum 1. The surface of the photosensitive drum 1 is charged to a uniform potential by applying a charging voltage obtained by superposing an AC voltage and a DC voltage from a charging power source (not shown) included in the charging unit to the charging roller 2.
The thickness of the metal support forming the cleaning member 8 is, for example, 1.2 mm to 2.0 mm, and the hardness of the polyurethane rubber is, for example, 60° to 80° (Wallace hardness). As the polyurethane rubber, it is possible to use a tip hardening blade in which the portion of the polyurethane rubber that contacts the photosensitive drum 1 is hardened. The cleaning member 8 removes the toner remaining on the photosensitive drum 1 after the toner image is transferred from the photosensitive drum 1 to the recording material P. The toner removed by the cleaning member 8 is stored in the collection container 9. One end of the cleaning member 8 is a fixed end attached to the frame body 15, and the other end of the cleaning member 8 is a free end in contact with the photosensitive drum 1. The other end (free end) of the cleaning member 8 extends from the downstream side to the upstream side in the rotation direction of the photosensitive drum 1 and is in contact with the photosensitive drum 1. That is, the direction extending from one end (fixed end) of the cleaning member 8 to the other end (free end) is opposite to the rotation direction of the photosensitive drum 1 in the region where the other end of the cleaning member 8 contacts.

<Collection sheet member>
Next, the recovery sheet member 14 will be described. As shown in FIG. 2, the recovery sheet member 14 is a component of the photoconductor unit 21 having the photosensitive drum 1, the charging roller 2, the cleaning member 8, and the recovery container 9. The recovery sheet member 14 has slidability. The recovery sheet member 14 is arranged upstream of the cleaning member 8 in the rotation direction of the photosensitive drum 1. When the cleaning member 8 removes the toner remaining on the photosensitive drum 1 after the toner image is transferred to the recording material P, the removed toner is stored in the recovery container 9. The collecting sheet member 14 collects the removed toner in the collecting container 9 and suppresses the toner contained in the collecting container 9 from leaking to the outside of the collecting container 9.

The recovery sheet member 14 is bonded to the bonding surface of the frame body 15 that constitutes the recovery container 9 by a double-sided tape or laser welding. The recovery sheet member 14 extends in the axial direction of the rotation center of the photosensitive drum 1, and is adhered to the frame body 15 so as to contact the photosensitive drum 1. One end of the recovery sheet member 14 is a fixed end attached to the frame body 15, and the other end of the recovery sheet member 14 is a free end in contact with the photosensitive drum 1. With the collecting sheet member 14 adhered to the frame body 15, the other end (free end) of the collecting sheet member 14 extends from the upstream side to the downstream side in the rotation direction of the photosensitive drum 1 and contacts the photosensitive drum 1. Touching. That is, the direction extending from one end (fixed end) of the recovery sheet member 14 toward the other end (free end) is substantially the same as the rotation direction of the photosensitive drum 1 in the region where the other end of the recovery sheet member 14 abuts. .. Further, the recovery sheet member 14 contacts the outer peripheral surface of the photosensitive drum 1 at a position upstream of the contact position between the cleaning member 8 and the photosensitive drum 1 in the rotation direction of the photosensitive drum 1. The collection sheet member 14 closes the gap between the photosensitive drum 1 and the frame 15 so that the toner contained in the collection container 9 does not leak out from the gap between the photosensitive drum 1 and the frame 15. The cleaning member 8 contacts the photosensitive drum 1 in the counter direction (reverse direction) of the rotating direction of the photosensitive drum 1 (direction R1), and the recovery sheet member 14 contacts the rotating direction of the photosensitive drum 1. Further, since the facing space between the cleaning member 8 and the collecting sheet member 14 is connected to the inside of the collecting container 9, the toner removed from the photosensitive drum 1 is collected from the gap between the photosensitive drum 1 and the frame 15. It is housed in the collection container 9 without leaking out of the container 9.

<Example 1>
Example 1 will be described. In the first embodiment, the following materials are used as the recovery sheet member 14.
Material: Polyphenylene sulfide (PPS) sheet Thickness: 38 μm
Work function: 5.80 eV
Young's modulus: 3000 N/m ²
Poisson's ratio: 0.38
The contact conditions of the recovery sheet member 14 with respect to the photosensitive drum 1 are shown below. The recovery sheet member 14 is adhered to the frame body 15 by laser welding. Penetration amount: 3.4 [μm]
Setting angle: 28.6[°]
Deflection amount δ: 1.24 [mm]
Contact pressure: 8.72×10 ⁻⁴ [N/mm]

Here, the penetration amount and the set angle will be described with reference to FIG.
3 is defined as the penetration amount [mm], and β is defined as the set angle [°]. The intrusion amount α represents the amount of the recovery sheet member 14 intruding into the outer shape of the photosensitive drum 1 when it is assumed that the photosensitive drum 1 is not present. That is, it is the distance from the surface of the photosensitive drum 1 to the free end (tip) of the recovery sheet member 14 assuming that the photosensitive drum 1 is not present. The recovery sheet member 14 on the assumption that the photosensitive drum 1 is not present is referred to as a recovery sheet member 14A. Further, the set angle β is formed between the tangent line S1 on the photosensitive drum 1 and the collecting sheet member 14A at the intersection where the outer shape of the photosensitive drum 1 and the collecting sheet member 14A intersect assuming that the photosensitive drum 1 is not present. Angle. Here, a straight line S3 extending from the fixed end of the collecting sheet member 14A toward the free end in a direction perpendicular to the straight line S2 extending along the collecting sheet member 14A, and a center of the photosensitive drum 1 starting from a point Q The distance from the point (rotation center position) O is M. The point Q is an arbitrary point on the edge portion of the free end (tip) of the recovery sheet member 14A and is arranged on the center point O side of the photosensitive drum 1. Further, the distance between the straight line S4 starting from the point Q and the straight line S3 starting from the point Q forming an angle of 45° with respect to the straight line S3 perpendicular to the straight line S2 starting from the point Q is N. And It is possible to calculate the penetration amount α and the set angle β by measuring the distances M and N and applying the equations 1 and 2 below. Here, r represents the radius [mm] of the photosensitive drum 1.

A method of calculating the contact pressure will be described with reference to FIG.
In FIG. 4, the recovery sheet member 14 is bent by the free end (tip) of the recovery sheet member 14 adhered and fixed to the seat surface 16 abutting on the photosensitive drum 1. The contact pressure P[N] per unit length (1 mm) in the longitudinal direction of the very thin collecting sheet member 14 as used in the image forming apparatus is 1.32×10 ⁻⁵ or more. It is preferably 74×10 ⁻² or less. The calculated value of the contact pressure P[N] is calculated by applying a study condition to be described later to the following formula (3) using a general formula of the load applied to the cantilever and the deflection.
Here, the bending amount of the recovery sheet member 14 is δ [mm], and the distance from the fixed end of the recovery sheet member 14 to the contact nip (contact position) between the photosensitive drum 1 and the free end of the recovery sheet member 14 (free The length is L [mm], and the thickness of the recovery sheet member 14 is h [mm]. E is the Young's modulus [N/mm ² ] of the recovery sheet member 14, and ν is the Poisson's ratio of the recovery sheet member 14.
P=δEh ³ /{4L ³ (L−ν ² )} (3)
Note that almost the tip of the recovery sheet member 14 is in contact with the photosensitive drum 1. Therefore, the distance L from the fixed end of the recovery sheet member 14 to the contact nip between the photosensitive drum 1 and the free end of the recovery sheet member 14 is approximated by the distance from the fixed end of the recovery sheet member 14 to the free end. I am using. Further, the flexure amount δ of the recovery sheet member 14 is determined by the contact portion between the free end of the recovery sheet member 14 and the photosensitive drum 1 and the edge portion of the free end of the recovery sheet member 14A on the center point O side of the photosensitive drum 1. It is used by approximating the distance between.

Further, the present invention was studied under the following conditions.
Radius of photosensitive drum 1=12 [mm],
Distance M=1.69 to 3.06 [mm]
Distance N=5.31 to 6.30 [mm]
Penetration amount δ=2.62 to 4.13 [mm]
The thickness h of the recovery sheet member 14 is 10 to 100 [μm]
Free length L of the recovery sheet member 14=3.39 to 4.79 [mm]

<Toner>
In the toner used in Example 1, the binder resin is a styrene resin and the release agent is an ester compound. The ester compound moderately acts on the styrene resin to soften the styrene resin. Since the ester compound has a high sharp melt property, the ester compound which is present without being compatible with the styrene resin is rapidly melted in the fixing region. Further, crystalline polyester is finely dispersed in the toner in order to improve the low temperature fixing performance of the toner. By uniformly dispersing polyester having high crystallinity in the toner, it becomes possible to rapidly plasticize the entire toner particles. In order to finely disperse the crystalline polyester, it is important to form a large amount of crystal nuclei of the ester compound inside the toner particles. For that purpose, it is necessary to suppress the crystallinity of the ester compound to some extent. Since the composition of the ester compound has a distribution, the crystallization rate of the ester compound is lower than that of the ester compound having a single composition, and a large amount of crystal nuclei is easily generated. Therefore, it is preferable that the composition of the ester compound has a distribution.

Further, in order to modify the surface property of the toner, an inorganic substance as an external additive may be formed on the toner surface. That is, the toner may include an external additive. As the inorganic substance formed on the toner surface, for example, silica, alumina, titanium oxide, aluminum oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, Wollastonite, diatomaceous earth, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like can be used. Moreover, you may use 1 type of these inorganic substances individually or in combination of 2 or more types. Further, the inorganic substance formed on the toner surface is preferably in the form of inorganic fine particles and adheres to the toner surface.

In Example 1, a magnetic toner having a negative charging property manufactured by the suspension polymerization method is used, and the number average particle diameter of the magnetic toner is about 8 μm. Although the toner manufactured by the suspension polymerization method is used in Example 1, the present invention is not limited to this. For example, a toner manufactured by a pulverization method or another polymerization method such as an emulsion polymerization method may be used. Here, the number average particle diameter of the toner is measured by a precision particle size distribution measuring apparatus Multisizer 3 manufactured by Beckman Coulter.
In Example 1, silicon oxide particles and titanium oxide particles are used as the inorganic substance formed on the surface of the toner, and the silicon oxide particles and titanium oxide particles are uniformly attached to the surface of the toner. Further, in Example 1, the number average particle size is about 20 nm, the silicon oxide particles are about 1.5% of the toner weight, and the number average particle size is about 50 nm, and about 0.8% of the toner weight. Silicon oxide particles and titanium oxide particles of about 0.1% of the toner weight are used.
The work function of the toner used in Example 1 is 6.03 eV. Details of the method for measuring the work function of the toner will be described later. The types and amounts of the inorganic substances formed on the toner surface and the work function of the toner in other examples will be described for each example.

Next, Comparative Examples 1 to 5 for confirming the effect of Example 1 and Examples 2 to 4 of the present invention will be described. The configurations of Comparative Examples 1 to 5 and Examples 2 to 4 are substantially the same as the configuration of Example 1 except as described below. In Comparative Examples 1 to 5 and Examples 2 to 4, functions or constituent elements corresponding to those in Example 1 are designated by the same reference numerals.

<Comparative Example 1>
The difference between Comparative Example 1 and Example 1 is that the number average particle size of silicon oxide particles formed on the toner surface is changed. In Comparative Example 1, the number average particle diameter is about 20 nm, and about 1.5% of the weight of the toner is uniformly attached to the surface of the toner.

<Comparative example 2>
The difference between Comparative Example 2 and Example 1 is that the number average particle size of silicon oxide particles formed on the toner surface is changed. In Comparative Example 2, the number average particle size is about 30 nm, and about 1.5% of the weight of the toner is uniformly attached to the surface of the toner.

<Comparative example 3>
The difference between the third embodiment and the first embodiment is that the material of the recovery sheet member 14 and the material of the toner base are changed. Materials of the recovery sheet member 14 and the toner in Comparative Example 3 are shown below.
・Collection sheet member 14
Material: PET sheet (Toray Industries: Lumirror (registered trademark))
Thickness: 38 [μm]
Work function: 5.33 [eV]
Flexural modulus: 2000 [N/m ² ]
Poisson's ratio: 0.21
The contact conditions of the recovery sheet member 14 with respect to the photosensitive drum 1 are shown below. The recovery sheet member 14 is adhered to the frame body 15 by laser welding.
Penetration amount: 3.4 [μm]
Setting angle: 28.6[°]
Deflection amount δ: 1.24 [mm]
Contact pressure: 5.20×10 ⁻⁴ [N/mm]
Toner In the magnetic toner of Comparative Example 3, the binder resin is a styrene resin and the release agent is an ester compound. The difference from Example 1 in Comparative Example 3 is that the crystalline polyester is not blended. Since the materials used for the toner base are different between Example 1 and Comparative Example 3, the work function of the toner is different. The work function of the toner of Comparative Example 1 is 5.65 eV.
Further, in Comparative Example 3, silicon oxide particles are used as the inorganic fine particles (external additive) formed on the toner surface, the number average particle diameter is about 50 nm, and the silicon oxide particles are about 1.5% of the toner weight. Evenly adhere to the surface of.

<Comparative example 4>
The difference from Comparative Example 4 in Example 1 is that the material of the recovery sheet member 14 is changed.
・Collection sheet member 14
Material: PET sheet (Toray Industries: Lumirror (registered trademark))
Thickness: 38 [μm]
Work function: 5.33 [eV]
Flexural modulus: 2000 [N/m ² ]
Poisson's ratio: 0.21
The contact conditions of the recovery sheet member 14 with respect to the photosensitive drum 1 are shown below. The recovery sheet member 14 is adhered to the frame body 15 by laser welding.
Penetration amount: 3.4 [μm]
Setting angle: 28.6[°]
Deflection amount δ: 1.24 [mm]
Contact pressure: 5.20×10 ⁻⁴ [N/mm]

<Comparative Example 5>
The comparative example 5 differs from the example 1 in that the conditions of the toner base are changed to the same conditions as the comparative example 3.

<Example 2>
The difference between the second embodiment and the first embodiment is that the material of the recovery sheet member 14 is changed.
・Collection sheet member 14
Material: Polytetrafluoroethylene (PTFE) sheet (Teflon (registered trademark))
Thickness: 50 [μm]
Work function: 6.0 [eV]
Flexural modulus: 560 [N/m ² ]
Poisson's ratio: 0.46
The contact conditions of the recovery sheet member 14 with respect to the photosensitive drum 1 are shown below. The recovery sheet member 14 is adhered to the frame body 15 by laser welding.
Penetration amount: 3.4 [μm]
Setting angle: 28.6[°]
Deflection amount δ: 1.24 [mm]
Contact pressure: 4.02×10 ⁻⁴ [N/mm]

<Example 3>
The difference between the third embodiment and the first embodiment is that the method of adhering the recovery sheet member 14 to the frame 15 is changed.
In the third embodiment, the double-sided tape is attached to the frame body 15, and the recovery sheet member 14 is provided on the double-sided tape to fix the recovery sheet member 14 to the frame body 15. The contact conditions of the recovery sheet member 14 with respect to the photosensitive drum 1 are shown below.
Penetration amount: 4.9 [μm]
Setting angle: 37.3 [°]
Deflection amount δ: 2.24 [mm]
Contact pressure: 1.57×10 ⁻³ [N/mm]

<Example 4>
The difference between the fourth embodiment and the first embodiment is that the thickness of the recovery sheet member 14 is changed. In Example 4, in Example 4, a PPS sheet having a thickness of 60 μm is adhered to the frame 15 by laser welding. The contact conditions of the recovery sheet member 14 with respect to the photosensitive drum 1 are shown below.
Penetration amount: 3.4 [μm]
Setting angle: 28.7[°]
Deflection amount δ: 1.24 [mm]
Contact pressure: 1.99×10 ⁻³ [N/mm]

<Combination of recovery sheet member and toner>
Next, the combination of the recovery sheet member 14 and the toner, which is the point of the present invention, will be described. The present inventors have found that the magnitude relationship of the work functions of the recovery sheet member 14 and the toner greatly affects the cleaning performance of the toner remaining on the photosensitive drum 1. Hereinafter, the evaluation method and the evaluation result will be described in detail.

<Evaluation method of each example and each comparative example>
Work function measurement In the present invention, focusing on the positional relationship between the recovery sheet member 14 and the toner in the charging series, the following three measuring methods were used for the three types of recovery sheet members 14 and the two types of toners A and B used in the experiment. It was evaluated by the work function measured by. Work function (Φ) is the energy required to extract electrons from the substance. When the work function difference between the two members is large, the electric field generated by triboelectric charging between the two members becomes large, and when the work function difference between the two members is small, the electric field between the two members becomes small. The electric field generated by triboelectric charging becomes small.

-Work function measuring method The work function can be measured by the following measuring method. The work function is quantified as energy (eV) for taking out electrons from the substance, and can evaluate the charge polarity of the recovery sheet member 14 and the toner.
The work function (Φ) is measured using a surface analyzer (AC-2 manufactured by Riken Keiki Co., Ltd.). In the surface analyzer, a deuterium lamp is used, the irradiation light amount is appropriately set, monochromatic light is selected by a spectroscope, spot size 4 [mm]×4 [mm], energy operation range 3.4 to 6.2. The sample is irradiated with [eV] and a measuring time of 10 [sec/1 point]. Then, the work function is measured by detecting the photoelectrons emitted from the sample surface and performing arithmetic processing using the work function meter software installed in the surface analysis device. The work function is measured with a repeatability (standard deviation) of 0.02 [eV]. The work functions of the recovery sheet member 14 and the toner were measured before the image formation. Further, the recovery sheet member 14 was measured after removing dust on the surface by air blow. In order to ensure data reproducibility, after forming an image, the sample was left for 24 hours under a condition of a use temperature of 25° C. and a humidity of 55% RH to be used as a measurement sample.

When measuring a sheet-shaped sample such as the recovery sheet member 14, the measurement light is emitted at a spot of 4 [mm]×4 [mm], and therefore a sample piece as a sample is at least 1 [cm]×1 [ [cm] size, and the test piece is fixed to the sample table for measurement. Further, when measuring a powder sample such as toner, the toner is smoothly arranged in a shallow dish-shaped container having a size of at least 1 [cm]×1 [cm] or more, and the container is fixed to the sample table. Measure.
When the excitation energy of monochromatic light is scanned from low to high in the surface analyzer, photon emission starts from a predetermined energy value [eV], and this predetermined energy value is taken as a work function [eV]. FIG. 5 shows an example of a graph of the work function of the recovery sheet member 14 obtained by using the surface analyzer. The circular mark in FIG. 5 shows the measurement result, and the circular marks are connected by an approximate line (broken line). The horizontal axis of FIG. 5 is photon energy [eV], and the vertical axis of FIG. 5 is Emission Yield [cps0.5] (0.5 electron power per unit photon). From FIG. 5, a constant slope [Emission Yield/photon energy] is obtained. In the case of FIG. 5, the work function is represented by the excitation energy [eV] at the inflection point (B) of the broken line. In FIG. 5, the work function is 5.33 [eV].

Cleaning Evaluation The cleaning evaluation was performed by detecting a streak-shaped image defect on the recording material P caused by the toner having passed through the cleaning member 8.
In this evaluation, first, the developing unit 20 of the process cartridge B is filled with toner. Then, after the process cartridge B is left in an environment of 23° C. and 50% RH for 24 hours, an image having a plurality of horizontal lines (lines along the axial direction of the photosensitive drum 1) having an image ratio of 4% is converted into an A4 size image. 200 sheets are continuously printed on the recording material P. The presence or absence of streak-shaped image defects was confirmed on all of the 200 printed recording materials P. Table 1 shows the results of this evaluation. The evaluation criteria for cleaning evaluation are shown below.
1: No streak-shaped image defects have occurred on all of the 200 recording materials P.
2: Streak-shaped image defects occur on the recording material P of 1 or more and less than 10 sheets.
3: Streak-shaped image defects occur on 10 to 50 recording materials P.
4: Streak-shaped image defects occur on 50 or more recording materials P.

Table 1 shows the measurement results of the work functions of the recovery sheet member 14 and the toner, the contact pressure of the recovery sheet member 14, and the results of cleaning evaluation in Examples 1 to 4 and Comparative Examples 1 to 5.

<Comparison between Example and Comparative Example>
The superiority of the present invention will be described by comparing each example with each comparative example. First, the superiority of the present invention over Comparative Example 1 will be described. As a result of intensive studies, the present inventors have found that by externally adding silicon oxide particles having a number average particle diameter of 50 nm or more to the toner, it is possible to efficiently suppress the negative tone of the residual toner due to the recovery sheet member 14. Found. In addition, making the residual toner strong negative means that the residual toner is excessively charged.

The above mechanism will be described by comparing Example 1 with Comparative Examples 1 and 2. In Example 1, silicon oxide particles having a number average particle diameter of 50 nm are externally added to the toner A. Compared with Example 1, Comparative Example 1 is different in that toner A is externally added with silicon oxide particles having a number average particle diameter of 20 nm. Further, compared with Example 1, Comparative Example 2 is different in that silicon oxide particles having a number average particle diameter of 30 nm are externally added to Toner A. In Example 1 and Comparative Examples 1 and 2, the same toner A is used, and the same PPS is used as the material of the recovery sheet member 14. Since the work function of the toner A is 6.03 ev and the work function of the recovery sheet member 14 is 5.80 ev, the work function difference between the toner A and the recovery sheet member 14 in Example 1 and Comparative Examples 1 and 2 is The value is the same 0.23 eV. In the cleaning evaluation of Example 1, streak-shaped image defects occurred in one or more and less than 10 recording materials P, whereas in the cleaning evaluation of Comparative Examples 1 and 2, 50 or more recording materials A streak-shaped image defect occurs on P. This is because the size of the number average particle diameter of the silicon oxide particles as the external additive affects the effect of suppressing strong negative. In Comparative Example 1, the number average particle diameter of the silicon oxide particles is 20 nm. Since the number average particle diameter of the silicon oxide particles in Comparative Example 1 is smaller than the number average particle diameter of the silicon oxide particles in Example 1, in Comparative Example 1, the toner particles in the state where the residual toner is densely aggregated easily. Therefore, in Comparative Example 1, only a part of the toner surface rubs against the recovery sheet member 14, and the effect of suppressing the negative tone is insufficient. In Comparative Example 2, the number average particle diameter of the silicon oxide particles is 30 nm, and the effect of suppressing strong negative development is insufficient as in Comparative Example 1. On the other hand, in Example 1, since the number average particle diameter of the silicon oxide particles is 50 nm, aggregation of toner particles is suppressed, and a gap is likely to occur between the toner particles. Therefore, the toner easily rolls at the contact portion between the recovery sheet member 14 and the photosensitive drum 1, and the chances that the surface of the toner rubs against the recovery sheet member 14 increase. As a result, in Example 1, since the number average particle diameter of the silicon oxide particles is 50 nm, the effect of suppressing the negative tone of the residual toner is efficiently exhibited, and thus the occurrence of streak-shaped image defects is suppressed.

In Comparative Example 3, toner is used as the material of the recovery sheet member 14 and toner B to which silicon oxide particles having a number average particle diameter of 50 nm are externally added is used. In the cleaning evaluation of Comparative Example 3, streak-shaped image defects occur on 10 or more and less than 50 recording materials P, and many streak-shaped image defects due to cleaning defects occur. This is because when the residual toner on the photosensitive drum 1 passes through the contact portion between the recovery sheet member 14 and the photosensitive drum 1, the toner rubs against the recovery sheet member 14 to become a strong negative. .. The strongly negative residual toner exerts a strong electrostatic adhesion force with the photosensitive drum 1, so that it becomes difficult to scrape and remove the residual toner from the photosensitive drum 1 by the cleaning member 8. Therefore, when a polymerized toner having a high circularity of the toner is used, the toner easily slips through the cleaning member 8 and the slipped toner remains on the photosensitive drum 1 and the image transferred onto the recording material P is formed in the subsequent image formation. Vertical streaks tend to occur.
Further, in Comparative Example 4, Toner B in Comparative Example 3 is changed to Toner A. The external additive in Comparative Example 4 is prepared under the same conditions as in Comparative Example 1. In the cleaning evaluation of Comparative Example 4, streak-shaped image defects occurred on 50 or more recording materials P, and more streak-shaped image defects occurred on the recording material P than in Comparative Example 3. ..

On the other hand, in Example 1, PPS is used as the material of the recovery sheet member 14, and the silicon oxide particles having the number average particle diameter of 50 nm are externally added to the toner A. In the cleaning evaluation, Example 1 has a smaller number of streak-shaped image defects than Comparative Examples 1 to 4. This is because the residual toner on the photosensitive drum 1 is prevented from rubbing at the contact portion between the recovery sheet member 14 and the photosensitive drum 1, so that the negative toner is prevented from becoming negative and the residual toner is kept at an appropriate charge amount. The factor is that it is dripping. In the first embodiment, the electrostatic adhesion force between the photosensitive drum 1 and the residual toner is reduced, and the cleaning member 8 can easily remove the residual toner. FIG. 6 shows a comparison of the toner charge amounts before and after passing through the recovery sheet member 14 between Comparative Example 4 and Example 1. The horizontal axis of FIG. 6 shows the charge amount (Q/M) of one toner, and the vertical axis of FIG. 6 shows the ratio (frequency) to the measured toner number. A dotted line A in FIG. 6 indicates the toner charge amount before the residual toner passes through the recovery sheet member 14. The solid line B in FIG. 6 indicates the toner charge amount after the residual toner has passed through the recovery sheet member 14 under the conditions of the first embodiment. The dotted line C in FIG. 6 indicates the toner charge amount after the residual toner has passed through the recovery sheet member 14 under the conditions of Comparative Example 4. As shown in FIG. 6, in Comparative Example 4, the residual toner was significantly increased after the residual toner passed through the recovery sheet member 14, whereas in Example 1, the residual toner was recovered sheet member. The increase in the toner charge amount after passing 14 is slight.

With respect to Example 1 and Comparative Examples 3 and 4, the mechanism considered to have a difference in the increase amount of the charge amount of the residual toner will be described below.
As a result of intensive studies, the present inventors have found that the difference between the work function of the toner and the work function of the recovery sheet member 14 (work function difference) has an influence on the increase in the charge amount of the residual toner. ..
When a resin material having a different work function is rubbed, a negative charge (negative charge) moves from a material having a small work function to a material having a large work function. As a result, a material having a low work function is positively charged, and a material having a high work function is negatively charged.
As shown in Table 1 above, the work function difference ((work function of toner)-(work function of recovery sheet member 14)) of Comparative Example 3 is 0.32 eV. The work function difference of Comparative Example 4 is 0.7 eV. In Comparative Example 3 and Comparative Example 4, the residual toner is strongly negative because of the combination of the recovery sheet member 14 and the toner having a large work function difference. In addition, since the work function difference between the recovery sheet member 14 and the toner in Comparative Example 4 is larger than the work function difference between the recovery sheet member 14 and the toner in Comparative Example 3, Comparative Example 4 has more streaks than Comparative Example 3. A lot of image defects are occurring. On the other hand, in Example 1, the combination of the recovery sheet member 14 and the toner is PPS and the toner A, and the work function difference is a small value of 0.23 eV, so that the negative negative effect on the residual toner is suppressed. Therefore, in the cleaning evaluation of Example 1, occurrence of streak-shaped image defects is suppressed.

Example 2 will be described. In Example 2, PTFE was used as the material of the recovery sheet member 14, and silicon oxide particles having a number average particle diameter of 20 nm were externally added to the toner A. The work function difference of Example 2 is 0.03 eV, which is a very small value, and streak-shaped image defects do not occur on the recording material P in the cleaning evaluation.

Next, Comparative Example 5 will be described. In Comparative Example 5, PPS is used as the material of the recovery sheet member 14, and silicon oxide particles having a number average particle diameter of 50 nm are externally added to the toner B. In the cleaning evaluation of Comparative Example 5, streak-shaped image defects occur on 10 or more and less than 50 recording materials P, and many streak-shaped image defects occur. This factor is due to the negative work function difference of Comparative Example 5. In Comparative Example 5, unlike Examples 1 and 2 and Comparative Examples 1 to 4, the value of the work function of the recovery sheet member 14 is larger than the value of the work function of the toner, so the recovery sheet member 14 is negative (negative). And the toner tends to be positively charged. The residual toner that has rubbed against the recovery sheet member 14 has a smaller charge amount than before the rubbing, and the electrostatic adhesion force between the photosensitive drum 1 and the residual toner becomes too small. Therefore, the residual toner does not pass through the recovery sheet member 14. Instead, it separates from the photosensitive drum 1 and easily adheres to the recovery sheet member 14. As a result, toner that adheres to the recovery sheet member 14 and stagnates at the contact portion between the recovery sheet member 14 and the photosensitive drum 1 is generated, so that there is an opportunity for rubbing between the residual toner on the photosensitive drum 1 and the recovery sheet member 14. And the effect of suppressing the residual toner from becoming negative is lost. From the above, it is preferable to prevent the residual toner from becoming negative, and to charge the residual toner to a weak charge amount. However, it is not preferable to reduce the charge amount of the residual toner to a value close to zero. As a condition for realizing this, it is preferable that the work function difference between the toner and the recovery sheet member 14 is 0 eV or more and 0.23 eV or less.

According to the present invention, by using the combination of the work function difference between the toner and the recovery sheet member 14 (work function of toner-work function of recovery sheet member 14) of 0 eV or more and 0.23 eV or less, residual toner is obtained. It is possible to suppress the strong negative. Further, by using the toner to which the silicon oxide particles having the number average particle diameter of 50 nm or more are externally added, the effect of suppressing the strong negative of the residual toner can be efficiently exhibited. As a result, it is possible to easily remove the residual toner by the cleaning member 8 and suppress the occurrence of streak-shaped image defects on the recording material P.

Example 3 and Example 4, which are more effective than Example 1, will be described.
In Example 3, the cleaning evaluation result was better than that in Example 1, and streak-shaped image defects did not occur on the recording material P. This is because the recovery sheet member 14 is adhered to the frame body 15 with the double-sided tape, so that the contact pressure of the recovery sheet member 14 on the photosensitive drum 1 for the thickness of 1 mm of the double-sided tape is increased. That is, the photosensitive drum 1 of the recovery sheet member 14
By increasing the contact pressure against the recovery sheet member 14, the residual toner layer in the contact nip between the recovery sheet member 14 and the photosensitive drum 1 is made uniform, and the chances of sliding between the residual toner and the recovery sheet member 14 increase. This further promotes the effect of suppressing the negative tone of the residual toner.

In addition, in Example 4, the cleaning evaluation result is better than that in Example 1, and no streak-shaped image defect occurs on the recording material P. This is because the thickness of the recovery sheet member 14 is 50 μm and the contact pressure on the photosensitive drum 1 is increased. Further, by setting the thickness of the recovery sheet member 14 to 50 μm, the waviness (waviness) of the recovery sheet member 14 when the recovery sheet member 14 is attached to the seating surface of the frame body 15 is reduced, and the recovery sheet member 14 is less susceptible to the photosensitive drum 1. A large contact pressure can be formed uniformly over the length of the photosensitive drum 1. The thickness of the recovery sheet member 14 may be 50 μm or more and 100 μm or less. This is because if the recovery sheet member 14 that is too thick is used, the photosensitive drum 1 may be damaged. FIG. 7 shows the toner charge amount distribution after the residual toner in Examples 1 and 5 has passed through the recovery sheet member 14. As shown in FIG. 7, in the fifth embodiment, as in the third embodiment, the contact pressure of the recovery sheet member 14 with respect to the photosensitive drum 1 is increased, so that the effect of suppressing the negative development of the residual toner is promoted. ..

From the above, the work function W(D) of the toner (developer) and the work function W(S) of the recovery sheet member 14 satisfy the following relational expression (A), and the toner has inorganic fine particles: It is preferable that the average primary particle size of at least one of the inorganic fine particles is 50 nm or more. As a result, it is possible to prevent the residual toner from becoming negative, and to prevent the residual toner from reaching the cleaning member 8 in an excessively charged state. As a result, it is possible to suppress the occurrence of defective images on the recording material P due to defective cleaning.
0≦W(D)−W(S)≦0.23 (A)
The average primary particle size indicates the number average particle size of the primary particles. The average primary particle size of at least one of the inorganic fine particles is 50 nm or more. The upper limit of the average primary particle size is preferably 200 nm or less, although it is not necessary to set the upper limit from the viewpoint of “suppressing the residual toner from becoming negatively strong”. The reason is that particles having an excessively large particle size may have low adhesion to the toner.

Further, the present invention is not limited to the configuration of the above embodiment. Although one kind of material is used as the recovery sheet member 14 in the above-mentioned embodiment, a two-layer material in which the base material is formed of a PET sheet and the PPS sheet is laminated thereon may be used instead of the PPS. Good. Regarding the material of the surface of the recovery sheet member 14 that contacts the photosensitive drum 1, the work function difference (W(D)−W(S)) between the toner and the recovery sheet member 14 satisfies the relational expression (A), The effect of the invention is exhibited.

Further, in the above embodiment, the binder resin is a styrene resin, the release agent is an ester compound, and the toner A in which the crystalline polyester is finely dispersed is used. The present invention is not limited to this toner A. Also in the case of the toner using other materials, the effect of the present invention is exhibited when the work function difference between the toner and the recovery sheet member 14 satisfies the relational expression (A).
The present invention can be applied to an image forming apparatus such as a copying machine and a printer, and a process cartridge used for the same.

DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 8... Cleaning member, 9... Collection container, 14... Collection sheet member, B... Process cartridge, P... Recording material, T... Toner

In order to achieve the above object, the cleaning device of the present invention,
A cleaning frame,
A cleaning member, one end of which is attached to the cleaning frame and the other end of which is a free end, carries a developer image made of a developer and is in contact with a rotatable image carrier. A cleaning member for removing the developer remaining on the image carrier after the developer image is transferred,
One end attached to the cleaning frame, you contact with the image bearing member at a position upstream of the rotation direction of the image bearing member than the contact position of the other end with said cleaning member and the image carrier sheet Members,
A cleaning device having:
The work function W(D) of the developer and the work function W(S) of the sheet member satisfy the following formula (A), and the developer has inorganic fine particles, and at least the inorganic fine particles are included. One kind of average primary particle diameter is 50 nm or more.
0≦W(D)−W(S)≦0.23 (A)
In order to achieve the above object, the process cartridge of the present invention is
An image bearing member that holds a developer image made of a developer and is rotatable;
A cleaning frame,
A cleaning member, one end of which is attached to the cleaning frame and the other end of which is a free end, contacts the image carrier, and after the developer image is transferred from the image carrier to the image carrier. A cleaning member for removing the remaining developer,
One end attached to the cleaning frame, you contact with the image bearing member at a position upstream of the rotation direction of the image bearing member than the contact position of the other end with said cleaning member and the image carrier sheet Members,
A process cartridge having
The work function W(D) of the developer and the work function W(S) of the sheet member satisfy the following formula (A), and the developer has inorganic fine particles, and at least the inorganic fine particles are included. One kind of average primary particle diameter is 50 nm or more.
0≦W(D)−W(S)≦0.23 (A)
In order to achieve the above object, the image forming apparatus of the present invention,
An image bearing member that holds a developer image made of a developer and is rotatable;
A transfer member for transferring the developer image carried on the image carrier to a recording material,
A cleaning frame,
A cleaning member, one end of which is attached to the cleaning frame and the other end of which is a free end, is in contact with the image carrier, and after the developer image is transferred from the image carrier to the image carrier. A cleaning member for removing the residual developer,
One end attached to the cleaning frame, you contact with the image bearing member at a position upstream of the rotation direction of the image bearing member than the contact position of the other end with said cleaning member and the image carrier sheet Members,
An image forming apparatus having:
The work function W(D) of the developer and the work function W(S) of the sheet member satisfy the following formula (A), and the developer has inorganic fine particles, and at least the inorganic fine particles are included. One kind of average primary particle diameter is 50 nm or more.
0≦W(D)−W(S)≦0.23 (A)

<Collection sheet member>
Next, the recovery sheet member 14 will be described. As shown in FIG. 2, the recovery sheet member 14 is a component of the photoconductor unit 21 having the photosensitive drum 1, the charging roller 2, the cleaning member 8, and the recovery container 9 . Recovered sheet member 14, the cleaning member 8 is disposed on the upstream side of the rotational direction of the photosensitive drum 1. When the cleaning member 8 removes the toner remaining on the photosensitive drum 1 after the toner image is transferred to the recording material P, the removed toner is stored in the recovery container 9. The collecting sheet member 14 collects the removed toner in the collecting container 9 and suppresses the toner contained in the collecting container 9 from leaking to the outside of the collecting container 9.

Claims (11)

A cleaning frame,
A cleaning member, one end of which is attached to the cleaning frame and the other end of which is a free end, carries a developer image made of a developer and is in contact with a rotatable image carrier. A cleaning member for removing the developer remaining on the image carrier after the developer image is transferred,
One end is attached to the cleaning frame, and the other end contacts the image carrier at a position upstream of the contact position between the cleaning member and the image carrier in the rotation direction of the image carrier, and A sheet member having slidability,
A cleaning device having:
The work function W(D) of the developer and the work function W(S) of the sheet member satisfy the following formula (A), and the developer has inorganic fine particles, and at least the inorganic fine particles are included. A cleaning device characterized by having an average primary particle size of 50 nm or more.
0≦W(D)−W(S)≦0.23 (A) The other end of the sheet member is a free end,
The deflection amount of the sheet member is δ, the Young's modulus is E, the thickness is h, the distance from one end of the sheet member to the contact nip between the sheet member and the image carrier is L, and the Poisson's ratio of the sheet member is When v, the contact pressure P of the sheet member calculated by the following formula (B) is 1.32×10 ⁻⁵ or more and 1.74×10 ⁻² or less. The cleaning device described in.
P=δEh ³ /{4L ³ (1-ν ² )} (B) The other end of the sheet member is a free end,
2. The direction extending from one end of the sheet member to the other end of the sheet member is the same direction as the rotation direction of the image carrier in the region where the other end of the sheet member abuts. The cleaning device according to 2. 2. A direction extending from one end of the cleaning member to the other end of the cleaning member is opposite to the rotation direction of the image carrier in a region where the other end of the cleaning member abuts. The cleaning device according to any one of 1 to 3. The cleaning device according to any one of claims 1 to 4, wherein the material of the sheet member is polyphenylene sulfide (PPS). The cleaning device according to any one of claims 1 to 4, wherein the material of the sheet member is polytetrafluoroethylene (PTFE). 7. The cleaning device according to claim 1, wherein the sheet member has a thickness of 50 μm or more and 100 μm or less. The cleaning device according to any one of claims 1 to 7, wherein the inorganic fine particles include silicon oxide particles and titanium oxide particles. The cleaning device according to claim 1, wherein at least one of the inorganic fine particles has an average primary particle size of 50 nm or more and 200 nm or less. An image bearing member that holds a developer image made of a developer and is rotatable;
A cleaning frame,
A cleaning member, one end of which is attached to the cleaning frame and the other end of which is a free end, contacts the image carrier, and after the developer image is transferred from the image carrier to the image carrier. A cleaning member for removing the remaining developer,
One end is attached to the cleaning frame, and the other end contacts the image carrier at a position upstream of the contact position between the cleaning member and the image carrier in the rotation direction of the image carrier, and A sheet member having slidability,
A process cartridge having
The work function W(D) of the developer and the work function W(S) of the sheet member satisfy the following formula (A), and the developer has inorganic fine particles, and at least the inorganic fine particles are included. A process cartridge having an average primary particle size of 50 nm or more.
0≦W(D)−W(S)≦0.23 (A) An image bearing member that holds a developer image made of a developer and is rotatable;
A transfer member for transferring the developer image carried on the image carrier to a recording material,
A cleaning frame,
A cleaning member, one end of which is attached to the cleaning frame and the other end of which is a free end, is in contact with the image carrier, and after the developer image is transferred from the image carrier to the image carrier. A cleaning member for removing the residual developer,
One end is attached to the cleaning frame, and the other end contacts the image carrier at a position upstream of the contact position between the cleaning member and the image carrier in the rotation direction of the image carrier, and A sheet member having slidability,
An image forming apparatus having:
The work function W(D) of the developer and the work function W(S) of the sheet member satisfy the following formula (A), and the developer has inorganic fine particles, and at least the inorganic fine particles are included. An image forming apparatus, wherein one kind of average primary particle diameter is 50 nm or more.
0≦W(D)−W(S)≦0.23 (A)

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