JP2001194810A - Method and device for electrophotographic image forming and processing cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotograhpic image forming method and the device of a cleaner-less system which is made small in size and light in weight, whose cost is reduced, and by which an image having an excellent quality is obtained by preventing the damage and wear of a photoreceptor surface and eliminating a defective image and residual toner left after transfer on a photoreceptor is recovered by at least a developing process. SOLUTION: The electrophotographic image forming method and the device have a process to contact-electrify the photoreceptor, a process to form an electrostatic latent image on the electrifying surface of the photoreceptor, a process to develop the electrostatic latent image as a toner image, a process to transfer the toner image on a transfer material and the residual toner left behind transfer on the photoreceptor surface after the transfer of the toner image is recovered by the developing process, so that the photoreceptor is repeatedly used, and an electrophotographic photoreceptor that uses toner with an additive, and whose universal hardness value HU in a surface coating material test is set to be >=200 N/mm2 (provided that a curve meaning the relation of hardness H and the push-in depth (h) of an indenter does not have an inflection point), and that has the coefficient of surface friction set to be 0.01-1.2 is adopted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotography of a so-called "cleanerless system" in which toner remaining on an electrophotographic photosensitive member after transfer is recovered at least in a developing step, and a special cleaning means is not provided. The present invention relates to an image forming method, an electrophotographic image forming apparatus, and a process cartridge used in the apparatus.

[0002]

2. Description of the Related Art A toner image is formed on a surface of an electrophotographic photosensitive member (hereinafter, also referred to as "photosensitive member") by an appropriate image forming process, and the toner image is transferred to a transfer material such as paper. The image forming apparatus (e.g., electrophotographic copying machine, fax machine, laser beam printer, etc.) is used for the image forming apparatus (e.g., copying and printing). It has been widely used in the past.

In a transfer-type image forming apparatus, when a toner image is transferred from the photoreceptor side to the transfer material side, not all of the toner is actually transferred, but part of the toner remains. The toner remaining on the photoconductor in this manner is referred to as “transfer residual toner”. Unless the transfer residual toner is removed from the photoreceptor, it is impossible to obtain a high-quality image free of dirt or the like in a repeated image forming process. For this reason, it is necessary to remove transfer residual toner from the photoconductor (photoconductor cleaning). Generally, a dedicated cleaning device (cleaner) such as a cleaning blade is provided and provided to remove transfer residual toner from the photoreceptor.

In recent years, a transferless image forming apparatus of a cleanerless system has emerged, in which a cleaning device is eliminated, and toner remaining after transfer on a photoreceptor after transfer is collected at least in a developing step (simultaneous development cleaning) and reused. ing.

[0005] Such an image forming apparatus of a cleaner-less system is ecologically effective, and also makes it possible to reduce the size, weight, and cost of the image forming apparatus.

On the other hand, a corona charger has been generally used as a charging step means for uniformly charging a photosensitive member to a predetermined polarity and potential. In this method, a corona charger is disposed in contact with a photoconductor in a non-contact manner, and the surface of the photoconductor is corona-charged by exposing the surface of the photoconductor to a corona shower generated from the corona charger to which a high voltage is applied.

In recent years, contact charging devices have been put into practical use because they have advantages such as lower ozone and lower power than corona chargers.

[0008] The contact charging device is used for charging a charged object such as a photoreceptor.
A conductive charging member (contact charging member) such as a roller type (charging roller), a blade type, a fur brush type, or the like is brought into contact, and a predetermined charging voltage (charging bias) is applied to the contact charging member to remove the charged object. It is charged to a predetermined polarity and potential.

[0009] Charging mechanism of contact charging (charging mechanism)
Has two types of corona charging system and charge injection charging system, and each characteristic appears depending on which is dominant.

In a cleanerless system image forming apparatus using a contact charging device as a charging means for a photoconductor, transfer residual toner on the photoconductor is carried to a contact portion (charging area) between the contact charging member and the photoconductor. It is temporarily collected by the contact charging member by being removed and adhering to and mixing with the contact charging member (simultaneous charging cleaning).

The toner collected by the contact charging member has its charging polarity adjusted, and is sequentially electrically discharged from the contact charging member onto the photosensitive member.

The toner discharged from the contact charging member onto the photoreceptor is carried to a developing area opposite to the photoreceptor and a developing device as a developing means, and is collected by the developing device (simultaneous cleaning with development). Used.

In the simultaneous cleaning with development, for example, a fogging bias (a potential difference between a DC component applied to the developing member of the developing device and a surface potential of the photoconductor) during transfer of the remaining toner on the photoconductor to the photoconductor after the next step. Can be collected by the fogging potential difference (Vback).

The amount of toner discharged from the contact charging member onto the photoreceptor is usually a small amount, and is in a very thin layer in a uniformly scattered state, which substantially adversely affects the next image exposure step. Has no effect. Further, generation of a ghost image due to the transfer residual toner pattern is also prevented.

The transfer residual toner on the photoreceptor often reverses its charging polarity due to peeling discharge at the time of transfer. However, it is necessary to collect the toner whose polarity has been reversed at the same time as development by a developing device. It is difficult. The contact charging member takes in the toner including the toner having the inverted charging polarity, converts the toner into the normally charged toner, and discharges the toner onto the photoreceptor, thereby facilitating simultaneous recovery of the transfer residual toner in the developing device.

In order to satisfy various performances, a metal oxide generally called an external additive is added to the toner. For example, in order to stabilize the triboelectrification property of a toner, use of hydrophobically treated alumina has been disclosed in
No. 75862 and Japanese Patent Application Laid-Open No. 61-275863.

Japanese Patent Application Laid-Open No. 48-47345 proposes a metal oxide powder as an abrasive.
JP-A-19535 and JP-A-56-128957 propose a metal oxide such as titanium oxide as a fluidizing agent. Further, JP-A-4-333739, JP-A-4-348354, JP-A-4-40467, and JP-A-5-72797 disclose fluidity imparting to toner particles, stabilization of toner charging, It is described that an amorphous titanium oxide powder surface-treated for the purpose of preventing filming or the like is used.

These are all inorganic substances, and the surface of the photoreceptor is worn by being rubbed on the surface of the photoreceptor.

[0019]

In the case where such a toner with an external additive is applied to an image forming apparatus of the above-mentioned cleanerless process using a contact charging device as a charging means for a photoreceptor, the photoreceptor is required. The transfer residual toner above is carried to the contact portion (charging area) between the contact charging member and the photoconductor and adheres to and mixes with the contact charging member. There is a problem that the surface of the photoreceptor is liable to be worn due to the rubbing of the agent and the photoreceptor, and as a result, image defects are particularly likely to occur.

The present invention has been made in view of the above, and is a transfer system using a toner with an external additive, in which an electrophotographic image of a cleanerless system for recovering transfer residual toner on a photoreceptor at least in a developing step. In a forming method, an electrophotographic image forming apparatus, and a process cartridge used in the apparatus, scratches and abrasion on the surface of a photoreceptor are prevented from occurring, and image defects due to the scratches and abrasion are eliminated. An object of the present invention is to provide an electrophotographic image forming method, an apparatus, and a process cartridge capable of obtaining a quality image.

[0021]

That is, the present invention provides a contact charging step of charging a surface of an electrophotographic photosensitive member, a step of forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member, A developing step of transferring the toner carried on the toner carrier to the formed electrostatic latent image to develop a toner image, a transfer step of transferring the developed toner image from the electrophotographic photosensitive member to a transfer material, Wherein the developing step also serves as a cleaning step of collecting toner remaining on the electrophotographic photosensitive member after transfer, wherein the toner has an external additive, The photoreceptor has a universal hardness HU of 200 N / mm ² or more (however, a curve showing the relationship between the hardness H and the indentation depth h does not have an inflection point), and has a surface friction coefficient. 0.01 to 1.2 An electrophotographic image forming method characterized by having surface properties.

Further, the present invention provides an electrophotographic photosensitive member, a contact charging means for charging the surface of the electrophotographic photosensitive member, an electrostatic latent image forming means for forming an electrostatic latent image on the charged electrophotographic photosensitive member surface, Developing means for transferring the toner carried on the toner carrier to the formed electrostatic latent image to develop the toner image,
A transfer unit for transferring the developed toner image from the electrophotographic photosensitive member to a transfer material, wherein the developing unit collects toner remaining on the electrophotographic photosensitive member after the transfer. The electrophotographic photoreceptor has a universal hardness HU of 200 N / mm ² or more (provided that the hardness H and the indentation depth h are equal to each other). The curve showing the relationship has no inflection point) and the coefficient of surface friction is 0.
An electrophotographic image forming apparatus having a surface characteristic of 01 to 1.2.

The present invention further provides an electrophotographic photosensitive member, a contact charging means for charging the surface of the electrophotographic photosensitive member, an electrostatic latent image forming means for forming an electrostatic latent image on the charged electrophotographic photosensitive member surface, Developing means for transferring the toner carried on the toner carrier to the formed electrostatic latent image and developing the toner image,
A transfer unit for transferring a developed toner image from an electrophotographic photosensitive member to a transfer material, the process cartridge being configured to be detachable from an electrophotographic image forming apparatus, wherein the electrophotographic photosensitive member and the charging unit And the developing means are integrally supported, the developing means also serves as a cleaning means for collecting toner remaining on the electrophotographic photoreceptor after transfer, the toner has an external additive, and the electrophotographic The photoreceptor has a universal hardness HU of 200N
/ Mm ² or more (however, a curve indicating the relationship between the hardness H and the indentation depth h does not have an inflection point) and has a surface friction coefficient of 0.01 to 1.2. A process cartridge characterized by having:

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has the above-mentioned structure, which suppresses scratches and scraping of the photoreceptor due to repeated use and prevents image defects and the like.

In the present invention, the transfer residual toner on the photoreceptor surface is collected at least in the developing step. The recovery of the toner is finally performed in the developing step, but is preferably performed in both the charging step and the developing step. As for the collection of the toner in the charging step and the developing step, it is possible to use the collecting method described in the above-mentioned conventional technique.

The present invention specifically addresses the technical problem that is particularly remarkable in the above-described specific process, that is, the technical problem specific to the cleanerless system using the contact charging method and a toner having an external additive. This problem has been solved by using an electrophotographic photosensitive member having surface characteristics.

The universal hardness in the present invention can be obtained by the following surface film physical property test.
The surface film physical property test is a test for analyzing the hardness of a thin film, a cured film, an organic film, and the like. In the measurement, a tester (Fisher Instruments H100V, manufactured by Fischer Instruments) shown in FIG. 4 is used. Then, using a diamond indenter 33 having a facing angle of 136 ° with a quadrangular pyramid diamond indenter, the measurement load was stepwise applied to the sample (electrophotographic photoreceptor) 31 and pushed into the sample film. At this time, the pressing depth h under a load is electrically detected and read. In FIG. 4, reference numeral 34 denotes a movable table, and 32 denotes a sample table.

The hardness H is represented by a value obtained by dividing a test load by a surface area of an indentation generated by the test load. The universal hardness HU is represented by a hardness at a set maximum indentation depth h _x (in the present invention, h _x = 1 μm). With respect to the hardness H and the universal hardness HU, higher values indicate higher film hardness (see FIG. 5). However, as shown in FIG. 6, in the curve showing the relationship between the hardness H and the indentation depth h in the surface film physical property test, the inflection point l showing a sharp change in the hardness H at the indentation depth h ' May have. This means that the film was broken and cracked at the indentation depth h '. Such a film whose surface is cracked is easily damaged by a deep wound, and is outside the scope of the present invention.

On the other hand, the method of measuring the surface friction coefficient in the present invention is as follows. As shown in FIG. 7, the measuring device was obtained by modifying Haydon surface property tester type 14 for measuring a drum-shaped sample. In FIG. 7, reference numeral 12 denotes a sample. By selecting the sample table 11, any of a drum-shaped and a plate-shaped sample can be measured. When measuring the surface friction coefficient, the urethane rubber blade 13
Is used. The rubber hardness of the urethane rubber blade 13 (Bancolan, manufactured by Bando Chemical Co., Ltd.) is 65 ± 3 °,
The dimensions are 5 mm wide, 10 mm long and 2 mm thick as shown in FIG. FIG. 9 is an enlarged view showing a contact portion between the urethane rubber blade 13 and the sample 12. The blade 13 has a contact angle of 30 ° with the sample 12 using a fixing screw 24 between an upper holder 22 and a lower holder 23 connected to the holder support arm 21 at the tip of the support 14.
It is fixed with a free length (the length of the portion of the blade 13 not restrained by the holders 22 and 23) of 8 mm.

At the time of measurement, a load 10 is applied to the blade 13 through the support 14 by the weight 16 placed on the pan 15.
g, the sample drum (electrophotographic photosensitive member) is moved in the generatrix direction in the forward direction with the blade 13 by the motor 20 together with the sample stand 11 on which the sample drum is fixed. The load at this time is read as a frictional force by the mechanism of the support point 17, the balancer 18, and the load converter 19 in FIG. Further, a 25 μm-thick polyethylene terephthalate (Mylar (trade name), manufactured by DuPont) film is used as a reference sample, wound around a cylinder having the same diameter as the sample, and the friction force is measured under the same conditions as the sample. The surface friction coefficient of the sample is calculated by the following equation (I).

[0031]

(Equation 1) Since the coefficient of surface friction is based on polyethylene terephthalate film, it is not affected by some variation in measurement conditions. In addition, it shows a constant value without being affected by the diameter of the photosensitive drum.

In the present invention, the following range of measurement conditions is allowed. Urethane rubber: hardness: 62 to 72 °, thickness: 1 to 5 m
m, Manufacturer: Bando Chemical Co., Ltd., Hokushin Rubber Co., Ltd., Tokai Rubber Co., Ltd. Polyethylene terephthalate film: Manufacturer: Toray Co., Ltd. (trade name: Lumirror), Teijin Limited (trade name: T)
R8550), DuPont (trade name: Mylar), etc .; thickness: 10 to 50 μm Drum diameter: 20 to 200 mm (even if the diameter of the drum is changed, the surface friction coefficient based on polyethylene terephthalate does not change.) All evaluations of surface properties at room temperature (about 2
1-25 ° C.).

According to the study of the present inventors, the universal hardness HU is 200 N / mm ² or more, preferably 220 N / mm ^2.
N / mm ² or more, and the surface friction coefficient is 0.01 to
If an electrophotographic photosensitive member having a surface characteristic of 1.2, preferably 0.02 to 1.1 is used, even in a so-called cleaner-less system, the photosensitive member does not have large scratches and the like, and image defects can be prevented. It has been found. The upper limit of the universal hardness HU is not particularly limited, but is 350 N / m.
About m ² can be cited as the upper limit.

The universal hardness HU is 200 N / mm ²
When the toner is less than the transfer residual toner, the external additive adhered to and mixed into the contact charging member of the contact charging means simultaneously with the transfer residual toner causes the surface of the photoreceptor to wear significantly when the contact charging member rubs against the surface of the photoreceptor. Or the amount of shaving increases, so that the printing durability life of the photoconductor is shortened.

The universal hardness HU is 200 N /
Even mm ² or more, when the surface friction coefficient is larger than 1.2, lubricity of the contact charging member and the photosensitive member surface falls, is strongly rubbed. That is, the external additive is strongly pressed and rubbed, and as a result, the shaving amount and the scratches increase, so that the printing durability life of the photoconductor is shortened.

Conversely, if the surface friction coefficient is extremely small, less than 0.01, there is almost no rubbing force between the contact charging member and the surface of the photoreceptor, and the toner remaining after transfer cannot be scraped off by the charging member. In addition, a ghost image due to the transfer residual toner pattern is easily generated.

In the present invention, it is preferable that the photoreceptor further has a surface characteristic having a contact angle with pure water of 95 ° or more, since the effects of the present invention can be more remarkably obtained. The upper limit of the contact angle with pure water is preferably less than 120 degrees.

The measurement of the contact angle is defined by the angle between the liquid surface and the surface of the photoreceptor (the angle inside the liquid) at the place where the free surface of the pure water is in contact with the photoreceptor using a drop-type contact angle meter.

In the present invention, since the surface of the photosensitive member is polished by rubbing with the contact charging member, even if the surface friction coefficient of the initial photosensitive member does not fall within the range of 0.01 to 1.2,
If the surface friction coefficient satisfies the range of 0.01 to 1.2 when the surface layer is removed at a maximum of 0.1 μm, it can be included in the scope of the present invention. The same can be said for the contact angle.

An embodiment of the present invention will be described below with reference to FIGS.
However, the present invention is not limited to this embodiment.

FIG. 1 is a schematic diagram showing an example of an image forming apparatus according to the present invention. The electrophotographic image forming apparatus of this embodiment is a laser beam printer using a transfer type electrophotographic process, a contact charging system, a reversal developing system, and a cleanerless system.

A is a printer main body, and B is an image reader (image reading device) mounted thereon. (1) Image Reader B In the image reader-B, the original G is placed on the upper surface of a fixed original table 10 (a transparent plate such as glass) with the surface to be copied facing down, and an original not shown is pressed thereon. Set it over the board.

The image reading unit 9 is provided with a document irradiation lamp 9a, a short focus lens array 9b, a CCD sensor 9c, and the like. When a copy start signal is input, the unit 9 is driven forward from the home position on the left side of the document table to the right side along the lower surface of the document table under the document table 10 to a predetermined forward end point. Is reached, the actuator is driven backward and returned to the initial home position.

In the forward drive process of the unit 9, the downward image surface of the placed set document G on the document table 10 is sequentially illuminated and scanned by the document irradiation lamp 9a of the unit 9 from the left side to the right side. The original surface reflected light of the illumination scanning light is imaged and incident on the CCD sensor 9c by the short focus lens array 9b.

The CCD sensor 9c includes a light receiving section, a transfer section, and an output section. The light signal is converted into a charge signal in the CCD light receiving unit, and the transfer unit sequentially transfers the light signal to the output unit in synchronization with the clock pulse. The output unit converts the charge signal into a voltage signal, amplifies the signal, reduces the impedance, and outputs the voltage signal. The analog signal thus obtained is subjected to well-known image processing, converted into a digital signal, and sent to the printer main unit A.

That is, the image information of the document G is photoelectrically read by the image reader B as a time-series electric digital pixel signal (image signal). (2) Printer Main Body A The rotating drum type electrophotographic photosensitive member 1 is driven to rotate at a predetermined peripheral speed (process speed) in the direction of arrow a around a central support shaft. The photosensitive member 1 of this example has a diameter of about 30 m.
m, and is driven to rotate at a peripheral speed of 100 mm / sec. The photoreceptor 1 will be described in detail in section (3) below.

In the present embodiment, the photosensitive member 1 is uniformly charged to a predetermined polarity and potential by a fur brush contact charging device in the rotating process. In this example, approximately -700
V is uniformly primary charged. The fur brush charger 3 as a contact charging member will be described later in detail in (4).

The uniformly charged surface of the rotating photoreceptor 1 is modulated by a laser exposure means (laser scanner) 2 in accordance with an image signal sent from the image reader B to the printer body A. By performing the scanning exposure with the laser light L, an electrostatic latent image corresponding to the image information of the document G photoelectrically read by the image reader B is sequentially formed on the surface of the rotating photoconductor 1.

The laser exposure means 2 comprises a solid-state laser device 2
a, a rotating polygon mirror (polygon mirror) 2b, an f-θ lens group 2c, a deflecting mirror 2d, and the like. On / off light emission control of the solid-state laser element 2a is performed at a predetermined timing by a light emission signal generator (not shown) based on the input image signal. The laser light emitted from the solid-state laser element 2a is converted into a substantially parallel light beam by a collimator lens system, scanned by a rotating polygon mirror 2b rotating at high speed, and f-θ.
A spot-like image is formed on the photoconductor 1 via the lens group 2c and the deflecting mirror 2d.

By such laser beam scanning, an exposure distribution for one scanning of an image is formed on the surface of the photoreceptor 1, and the sub-scanning is performed by rotating the photoreceptor 1. An exposure distribution is obtained. That is, the light of the solid-state laser element 2a, whose emission is controlled by 0N / 0FF corresponding to the image signal, is scanned on the uniformly charged surface of the rotary photoconductor 1 by the rotary polygon mirror 2b rotating at high speed.
An electrostatic latent image corresponding to the scanning exposure pattern is sequentially formed on the surface. That is, the potential of the exposed portion irradiated with the laser beam drops on the surface of the rotating photoconductor 1 (bright portion potential), and the potential of the unexposed portion (dark portion potential) which is not irradiated corresponds to the exposure pattern. The formed electrostatic latent image is formed.

The electrostatic latent image formed on the surface of the rotating photoreceptor 1 is successively developed as a toner image by the developing device 4 in the case of the present embodiment. The configuration of the developing device 4 will be described later in detail in section (5).

On the other hand, the transfer material P loaded and stored in the paper feed cassette 5 is fed out and fed one by one by a paper feed roller 5a, and is transferred to the photoconductor 1 at a predetermined control timing by a registration roller 5b. The transfer material P is fed to a transfer portion 7e which is a contact nip portion with a transfer device 7 as a means.
The toner image on the photosensitive member 1 side is electrostatically transferred to the surface.

The transfer device 7 in this embodiment is a belt transfer device, which suspends an endless transfer belt 7a between a driving roller 7b and a driven roller 7c, and is substantially the same as the rotational peripheral speed of the photosensitive member 1 in the direction of arrow d. It is driven to rotate at the peripheral speed. A transfer charging blade 7d is provided inside the endless transfer belt 7a,
A substantially intermediate portion of the belt portion on the ascending side of the belt 7a is brought into contact with the surface of the photosensitive drum 1 by the blade 7d to form a transfer portion (transfer nip portion) 7e.

The transfer material P is conveyed to the transfer section 7e on the upper surface of the belt 7a on the ascending side. When a predetermined transfer bias is supplied from the transfer bias application power supply S3 to the transfer charging blade 7d at the time when the leading end of the transport transfer material P enters the transfer portion 7e, charging of the opposite polarity to the toner from the back side of the transfer material P is performed. Then, the toner images on the photoconductor 1 are sequentially transferred onto the upper surface of the transfer material P.

In the present embodiment, the transfer method is configured as described above, but the transfer method used in the present invention may be roller transfer, blade transfer, corona discharge transfer, or the like. The present invention can be applied not only to single-color image formation but also to an image forming apparatus for forming a multicolor, full-color image by multiple transfer or the like using an intermediate transfer body such as a drum or a belt.

The transfer belt 7a also serves as a means for transporting the transfer material P from the transfer unit 7e to the fixing device 6, and the transfer material P that has passed through the transfer unit 7e is separated from the surface of the rotating photoreceptor 1 and is transferred to the transfer belt 7a. The toner image is conveyed and introduced into the fixing device 6, and is discharged to the discharge tray 8 as a copy or a print after receiving the thermal fixing of the toner image.

The printer main body A of this embodiment does not include a dedicated cleaning device (cleaner) for removing the transfer residual toner remaining on the surface of the rotary photoreceptor 1 after the transfer of the toner image onto the transfer material P. This is a cleanerless system device in which the charger 3 and the developing device 4 also serve as cleaning means for collecting transfer residual toner remaining on the surface of the photoconductor 1. This will be described in detail in (6) below.

Further, in the method and apparatus of the present invention, the process equipment such as the photoreceptor 1, the charging means 3, and the developing device 4 are detachably attached to and detachable from the image forming apparatus main body. It can also be of a device configuration. For example, an electrophotographic photosensitive member, a contact charging unit using a magnetic brush, and a developing device capable of supplying toner can be integrally supported, and a process cartridge detachable from the main body of the image forming apparatus can be provided (FIG. 10). In FIG. 10, 1
02 is a contact charging unit, 121 is a charging sleeve, 122 is a magnet, 123 is a magnetic brush formed of magnetic particles, L is exposure light, 103 is a developing unit, 103a is a developing sleeve, 103b is a magnet, 104 is a transfer roller, P is a transfer material, R is a transfer unit, 105 is a fixing unit, S1
S3 denotes a power source, and 200 denotes a process cartridge.
Further, in the present invention, a full-color image can be obtained by sequentially transferring toner images of each color to a transfer material on a transfer belt using four process cartridges for each color of yellow, magenta, cyan and black. (3) Photoconductor 1 The electrophotographic photoconductor used in the present invention has the above-mentioned surface characteristics,
That is, the universal hardness HU in the surface film property test is 200 N / mm ² or more (however, the curve showing the relationship between the hardness H and the indentation depth h does not have an inflection point), and the surface friction The surface has a coefficient of 0.01 to 1.2. Further, an electrophotographic photoreceptor having a surface characteristic in which the contact angle of the surface with pure water is preferably 95 degrees or more.

The electrophotographic photoreceptor having such surface characteristics may be formed, for example, by using a specific resin as a binder resin for the surface layer of an electrophotographic photoreceptor having a normal configuration so that the universal hardness is within the above range. Also, in order to make the surface friction coefficient or the contact angle of the surface with pure water the above range, a specific amount of fluororesin powder is uniformly dispersed in the surface layer,
It is obtained by polishing the surface as needed.

The means for adjusting the universal hardness include a binder resin and a charge generation material or a charge transport material dispersed and dissolved in the binder resin, or a conductive material such as a metal and its oxides, nitrides, salts, alloys and carbon. Changing the types of materials and their ratios can be mentioned. In other words, depending on the material dispersed in the binder resin, in the case of the above-mentioned materials, the smaller the amount of the dispersed material, the larger the universal hardness. Further, as another means, it is also possible to change the molecular weight, the number of polymerization functional groups, and the like of the binder resin. That is, if the molecular weight of the binder resin is increased, the universal hardness is increased, and if the degree of crosslinking of the resin is increased by increasing the number of polymerized functional groups, the universal hardness is increased. Furthermore, it may change depending on the dispersion state of the fluorine resin powder or the like.

Although these requirements naturally affect the surface friction coefficient and the contact angle, the universal hardness and the surface coefficient,
Alternatively, no fixed relationship has been found between universal hardness and contact angle.

In the present invention, it is important that the above-mentioned surface characteristics are satisfied, and the means for achieving the same is not particularly limited. For example, as a method of controlling the surface friction coefficient and the contact angle, in addition to selecting the type and amount of the material particles to be used, polishing of the surface of the photoconductor after the preparation of the photoconductor may be mentioned.

As a method of polishing, for example, when the photoreceptor is a drum type, it is rotated, and a # C-2000 wrapping tape made by Fuji Film, a polishing film # 2000 (aluminum oxide) made by Sumitomo 3M, etc. are put there. For example, a method of applying pressure while making contact may be used.

Specific examples of the above-mentioned fluororesin powder include:
Tetrafluoroethylene, hexafluoropropylene,
Trifluoroethylene, chlorotrifluoroethylene,
Polymers such as vinylidene fluoride, vinyl fluoride and perfluoroalkyl vinyl ether, and copolymers thereof, and the like can be given.

The number average particle diameter of the fluororesin powder is 0.01
Preferably, the number average molecular weight is in the range of 3,000 to 5,000,000.

The fluororesin powder is usually used by being dispersed in a composition used for forming the outermost surface layer of the photoreceptor. The dispersion of the fluororesin powder in the composition constituting the outermost surface layer of the photoreceptor is performed using, for example, a sand mill, a ball mill, a roll mill, a homogenizer, a nanomizer, a paint shaker, an ultrasonic device, or the like. For dispersion, a fluorine-based surfactant, a graft polymer, a coupling agent, or the like may be used as an auxiliary.

The content of the fluororesin powder is preferably from 4 to 70% by mass, more preferably from 10 to 55% by mass, based on the total mass of the constituent composition of the outermost surface layer of the photoreceptor. If it is less than 4% by mass, the surface energy may not be sufficiently reduced, and if it exceeds 70% by mass, the film strength of the surface layer may be reduced.

The configuration of the electrophotographic photosensitive member used in the present invention is not particularly limited as long as it has the above-mentioned surface characteristics and functions as an electrophotographic photosensitive member. In general, a photoconductor having a configuration in which a photosensitive layer is provided on a conductive support is used, but a protective layer is provided on the photosensitive layer, and an undercoat layer is provided between the conductive support and the photosensitive layer. Alternatively, a conductive layer may be provided. Therefore, the outermost surface layer of the photoreceptor is a photosensitive layer or a protective layer, and these layers are made of a binder resin and a charge generating material contained in the binder resin in an appropriate amount, or a charge transport material or a conductive material, For example, a photoreceptor having the above-described surface characteristics can be obtained by incorporating a fluorine-based resin powder as described above and polishing the surface as necessary.

The photosensitive layer of the electrophotographic photosensitive member used in the present invention has a single layer or a laminated structure. For a single-layer structure,
The photosensitive layer contains both a charge generating material for generating carriers and a charge transporting material for transporting carriers. In the case of a laminated structure, a charge generation layer containing a charge generation material for generating carriers and a charge transport layer containing a charge transport material for transporting carriers are laminated to form a photosensitive layer. The surface layer may be formed on either the charge generation layer or the charge transport layer.

The single-layer photosensitive layer preferably has a thickness of 5 to 100 μm, particularly preferably 10 to 60 μm. Further, the charge generation material and the charge transport material are added to the total mass of the layer by 2%.
It is preferably contained in an amount of from 0 to 80% by mass, and particularly preferably from 30 to
It is preferably 70% by mass. The single-layer photosensitive layer contains a binder resin in addition to the charge generation material and the charge transport material, and may contain an ultraviolet absorber, an antioxidant, and other additives as necessary.

In the laminated photosensitive layer, the thickness of the charge generating layer is preferably from 0.001 to 6 μm, and particularly preferably from 0.01 to 2 μm. The content of the charge generation material is preferably from 10 to 100% by mass, and particularly preferably from 40 to 100% by mass, based on the total mass of the layer. The charge generation layer may be composed of only the charge generation material, but in other cases, it may contain the above-mentioned binder resin and the like. The thickness of the charge transport layer is 5 to 5.
It is preferably 100 μm, especially 10 to 60 μm
m is preferable. The charge transport material content is 20
To 80% by mass, particularly 30 to 70% by mass.
It is preferable that the content is mass%. The charge transport layer contains a binder resin in addition to the charge transport material, and may contain other optional components similar to those described above.

The charge generation material used in the present invention includes a phthalocyanine pigment, a polycyclic quinone pigment, an azo pigment,
Perylene pigments, indigo pigments, quinacridone pigments, azulenium salt dyes, squarylium dyes, cyanine dyes,
Examples include pyrylium dyes, thiopyrylium dyes, xanthene dyes, quinone imine dyes, triphenylmethane dyes, styryl dyes, selenium, selenium-tellurium, amorphous silicon, and hardened cadmium.

The charge transport materials used in the present invention include pyrene compounds, carbazole compounds, hydrazone compounds, N, N-dialkylaniline compounds, diphenylamine compounds, triphenylamine compounds, triphenylmethane compounds, pyrazoline compounds, styryl compounds, and the like. And stilbene compounds.

As the binder resin used for the photosensitive layer,
Polyester, polyurethane, polyarylate, polyethylene, polystyrene, polybutadiene, polycarbonate, polyamide, polypropylene, polyimide, polyamideimide, polysulfone, polyallyl ether, polyacetal, phenolic resin, acrylic resin, silicone resin, epoxy resin, urea resin, allyl resin, Alkyd resins and butyral resins are exemplified. Furthermore, reactive epoxy and (meth) acrylic monomers and oligomers can be used after mixing and curing.

The electrophotographic photosensitive member used in the present invention may have a protective layer laminated on the photosensitive layer as described above. The thickness of the protective layer is preferably 0.01 to 20 μm,
In particular, the thickness is preferably 0.1 to 10 μm. The protective layer generally has a structure in which a charge generation material or a charge transport material, a metal and its oxides, nitrides, salts, alloys, and conductive materials such as carbon are dispersed in a binder resin.
Examples of the binder resin, charge generation material, and charge transport material used for the protective layer include the same materials as those used for the photosensitive layer.

The conductive support used in the electrophotographic photoreceptor used in the present invention may be made of a metal or an alloy such as iron, copper, nickel, aluminum, titanium, tin, antimony, indium, lead, zinc, gold and silver, Alternatively, oxides, carbon, conductive resins, and the like thereof can be used. The shapes include a cylindrical shape, a belt shape, and a sheet shape. The conductive material may be molded, but may be applied as a paint or may be deposited. The conductive support used in this example is a cylindrical support having a diameter of about 30 mm as described above.

As described above, an undercoat layer may be provided between the conductive support and the photosensitive layer. The undercoat layer is mainly made of a binder resin, but may contain the conductive material or the compound having an acceptor property. As the binder resin for forming the undercoat layer, polyester, polyurethane, polyarylate, polyethylene, polystyrene, polybutadiene, polycarbonate, polyamide, polypropylene,
Polyimide, polyamide imide, polysulfone, polyallyl ether, polyacetal, phenolic resin, acrylic resin, silicone resin, epoxy resin, urea resin,
Allyl resins, alkyd resins, butyral resins, and the like.

Further, as described above, a conductive layer may be provided between the conductive support and the photosensitive layer. When the photoreceptor has both an undercoat layer and a conductive layer, usually, a conductive support, a conductive layer, an undercoat layer, and a photosensitive layer are laminated in this order. The conductive layer generally has a structure in which the conductive material is dispersed in the same binder resin as used in the undercoat layer.

As a method for producing the electrophotographic photosensitive member used in the present invention, a method is generally used in which an undercoat layer, a photosensitive layer, a protective layer and the like are laminated on a conductive support by vapor deposition or coating. . Bar coating, knife coating,
Roll coater, attritor, spray, dip coating,
Electrostatic coating and powder coating are used. Further, in order to form the undercoat layer, the photosensitive layer, the protective layer, and the like by a coating method, the components of each layer are dissolved and dispersed in an organic solvent or the like, and a solution or dispersion liquid is applied by the above method. After that, the solvent may be removed by drying or the like. Or,
When a reaction-curable binder resin is used, the constituent components of each layer are dissolved and dispersed in a resin raw material component and an appropriate organic solvent added as needed, and a solution or dispersion liquid is applied by the above method. After that, for example, the resin raw material is reacted and cured by heat or light, and the solvent may be removed by drying or the like as necessary.

In the present invention, the photoreceptor 1 has a size of 10 ⁹ to
A surface layer having a resistance of 10 ¹⁴ Ω · cm is preferable, for example, because injection charging described in JP-A-8-69155 can be realized and generation of ozone can be prevented. This is because, in the case of charging involving generation of ozone, if the photoconductor has high mechanical durability as in the present invention,
This is because the photoconductor is easily deteriorated by ozone products, but is not deteriorated in the case of injection charging. (4) Fur brush charger 3 The fur brush charger 3, which is a contact charging member, is of a rotary type in the case of this embodiment. FIG. 2 is an enlarged schematic cross-sectional view of the fur brush charger 3. As shown in FIG. 2, the fur brush charger 3 is disposed in contact with the photoconductor 1, and functions as a contact charging member. The fur brush 38 has an outer diameter of 1
The hair was implanted on a core bar 37 of 0 mm. The fur brush part 38 has a bristle length of 3 mm and a resistance value of 1 × 10 ⁶ Ω ·
cm of conductive fiber at a density of 15500 fibers / cm ² (100,000 fibers / inch ² ) by flocking on a cored bar 37. The charger container 36 has a substantially C-shaped cross section in which a fur brush roll including the cored bar 37 and the fur brush portion 38 is accommodated, and an electrode 39 is provided on the inner wall surface of the charger container 36. In this embodiment, a conductive resin material in which carbon black is dispersed in an acrylic resin and adjusted to have a resistance of 10 ³ to 10 ⁴ Ω · cm is disposed around the fur brush portion 38 as an electrode 39.

The fur brush charger 3 has a fur brush portion 38 that faces outward from the opening of the charger container 36.
Is brought into contact with the surface of the photoreceptor 1 so as to be substantially parallel to the photoreceptor 1. In this example, the fur brush charger 3 is connected to the photoconductor 1
The fur brush portion 38 is formed so as to have a contact nip width (charging area) n1 of about 7 mm.

The core metal 37 of the fur brush charger 3 has a rotation peripheral speed of 100 mm / sec in the clockwise direction b of the arrow opposite to the rotation direction a of the photoconductor 1 (counter direction) in the charging area n1. 200mm / sec
To rotate.

A predetermined charging bias is applied to the metal core 37 from a charging bias applying power source S1.

In this example, the core metal 37 is supplied with a direct current voltage (DC) of -700 V, an alternating voltage (AC, a peak-to-peak potential (V _PP )).
(AC bias application method) by applying an oscillating voltage with a superimposed frequency of 0.7 kV and a frequency (Vf) of 1.0 kHz (AC bias application method), so that the surface of the rotary photoconductor is contact-charged to about -700 V.

With the rotation of the core bar 37, the fur brush 3
8 rotates in the same direction and rubs the surface of the photoreceptor 1 in the charged area n1, and charges are given to the photoreceptor 1 from the conductive fibers constituting the fur brush portion 38, so that the photoreceptor surface 1 has a predetermined polarity. Contact charge is uniformly applied to the potential.

In the present embodiment, a rotary type charger is used as the fur brush charger 3 as the contact charging member, but the invention is not limited to this configuration. The contact charging member is not limited to the fur brush charger 3, but may be, for example, a magnetic brush charging device or a charging roller.

As the waveform of the primary charging alternating voltage component for the contact charging member, a sine wave, a rectangular wave, a triangular wave, or the like can be used as appropriate. For example, a DC power supply is periodically turned on / off.
The voltage of the square wave formed by the above operation can also be used. (5) Developing device 4 Generally, the developing method of the electrostatic latent image is roughly classified into the following four types. a. A method in which non-magnetic toner is coated on a sleeve with a blade or the like, magnetic toner is coated on the sleeve by magnetic force, and is conveyed to a development area and developed in a non-contact state with a photoconductor (one-component non-contact development) ). b. A method in which the toner coated as described above is developed in contact with the photoreceptor (one-component contact development). c. A method in which a mixture of a toner and a magnetic carrier is used as a developer, coated on a sleeve by magnetic force, transported to a development area, and developed in contact with a photoreceptor (two-component contact development). d. A method of developing the above two-component developer in a non-contact state (two-component non-contact development).

In the present embodiment, which will be described in detail below, the two-component contact developing method (c) is used as a method for developing an electrostatic latent image, but other developing methods described above can also be used. is there. Preferably, one-component contact development (b) or two-component contact development (c), in which the developer is developed in contact with the photoreceptor, is effective in increasing the simultaneous recovery effect during development. Actually, the two-component contact developing method (c) is often used from the viewpoint of high image quality and high stability of an image.

The developing device 4 in this embodiment is a two-component contact developing device (two-component magnetic brush developing device). FIG. 3 is an enlarged schematic cross-sectional view of the developing device 4. In FIG. 3, reference numeral 41 denotes a developing sleeve as a toner carrier which is driven to rotate in the direction of arrow c; 42, a magnet roller fixedly arranged in the developing sleeve 41; 43 and 44, a developer stirring screw; A regulating blade arranged to form a thin layer of the agent T on the surface of the developing sleeve 41;
46 is a developing container, and 47 is a toner hopper for replenishment.

The developing sleeve 41 is arranged so that the region closest to the photosensitive member 1 is at least about 500 μm at least at the time of development, and a thin layer of the developer T formed on the surface of the developing sleeve 41 is exposed to light. It is set so that development can be performed in a state of contact with the body 1. n2 is a developer contact area (development area, development site) with respect to the photoconductor 1.

The two-component developer T used in this example is a mixture of an externally added toner t and a magnetic carrier c for development prepared by the following method.

The toner used in the present invention may be any toner as long as it has an external additive. From the viewpoint of improving transfer efficiency, the external additive preferably has a large particle diameter. In particular, in a cleanerless system as in the present invention, a toner must be used so as to obtain as high a transfer efficiency as possible. However, if the particle size of the external additive is too large, for example, a number average particle size of 0.0
When the thickness is 3 μm or more, abrasion and scratches on the photoreceptor and consequently image defects are more likely to occur. Therefore, the present invention works very effectively in a system using an external additive having such a large particle size.

The method for measuring the particle size of the external additive in the present invention is as follows.

Electron microscope S-800 (manufactured by Hitachi, Ltd.)
The toner was photographed at a magnification of 10,000 to 20,000 times using an external additive.
One hundred μm or more of those having a size of μm or more were randomly extracted, measured using a measuring instrument such as a caliper, and averaged to obtain the number average particle diameter of the external additive.

In the examples described later, the weight average particle diameter of 6 μm produced by the suspension polymerization method was used as the externally added toner t.
m, an externally added toner obtained by adding an external additive composed of alumina fine particles and silica fine particles to a negatively charged spherical toner (negative toner).

The following is an example of the production of the developer T used in this example. (I) Production of externally added toner t-125 parts by mass of styrene-35 parts by mass of methyl methacrylate-40 parts by mass of n-butyl acrylate-14 parts by mass of copper phthalocyanine pigment-3 parts by mass of Al compound of ditertiary butyl salicylic acid-10 parts by mass of saturated polyester Parts (acid value 10, peak molecular weight 9,100) ester wax 40 parts by weight (weight average molecular weight (Mw): 450, number average molecular weight (M
n): 400, Mw / Mn: 1.13, melting point 68 ° C., viscosity: 6.1 mPa · s, Vickers hardness: 1.2, SP
Value: 8.3) The above formulation was heated to 60 ° C., and using a TK homomixer (manufactured by Tokushu Kika Kogyo) at 10,000 rpm
To dissolve and disperse uniformly. To this, polymerization initiator 2,
2'-azobis (2,4-dimethylvaleronitrile) 1
0 parts by mass was dissolved to prepare a polymerizable monomer composition.

Separately, 710 parts by mass of ion-exchanged water was added to 0.1 part by mass.
After 450 parts by mass of an aqueous solution of M-Na ₃ PO ₄ was added and heated to 60 ° C., the mixture was stirred at 1,300 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). 1.0
68 parts by mass of an M-CaCl ₂ aqueous solution was gradually added, and Ca ₃
An aqueous medium containing (PO ₄ ) ₂ was obtained.

The polymerizable monomer composition was charged into the aqueous medium, and 2 parts by mass of polyethylene was added.
Under a N ₂ atmosphere at ℃ 1 with a TK homomixer
The mixture was stirred at 000 rpm for 20 minutes to granulate the polymerizable monomer composition. Thereafter, the temperature was raised at 80 ° C. while stirring the aqueous medium with a paddle stirring blade, and a polymerization reaction was performed for 8 hours.

After completion of the polymerization reaction, the mixture was cooled, hydrochloric acid was added to dissolve calcium phosphate, and then filtered, washed with water and dried to obtain polymer particles (toner particles).

The externally added toner t was prepared by adding 1.0 part by mass and 1.0 part by mass of alumina fine particles and silica fine particles to 100 parts by mass of the toner particles obtained above, and mixed with a Henschel mixer. It was produced by doing. The number average particle diameters of the alumina fine particles and the silica fine particles were 0.015 μm and 0.035 μm, respectively. The above alumina fine particles have been subjected to a hydrophobic treatment with an alkylalkoxysilane. (Ii) Production of Developer T As the magnetic carrier c, the saturation magnetization was 205 kA / m (2
50 emu / cm ³ ) with a volume-based 50% particle size of 35 μm
A developer T was prepared by mixing the above-mentioned externally added toner t and the above magnetic carrier c at a mass ratio of 6:94 using m magnetic carriers.

The developing sleeve 41 is driven to rotate at a predetermined peripheral speed in a direction indicated by an arrow c which is a forward direction to the rotating direction of the photosensitive member 1 in the developing area n2. Along with the rotation, the developer T in the developing container 46 is pumped by the S ₂ pole of the magnet roller 42 to the surface of the developing sleeve 41 and transported. In the transporting process, the developer T is perpendicular to the developing sleeve 41. The layer thickness is regulated by the arranged regulating blade 45, and a thin layer of the developer T is formed on the developing sleeve 41. Napping is formed when the developer formed as a thin layer is conveyed to the developing area n2 corresponding to the developing pole S ₁ in transport pole N ₁ by a magnetic force. The electrostatic latent image on the rotating photoconductor 1 is developed as a toner image in the development area n2 by the externally added toner t in the developer T formed in the spike shape. In this example, the electrostatic latent image is reversely developed.

The developing sleeve 41 that has passed the developing area n2
The upper developer thin layer enters the developing container 46 with the subsequent rotation of the developing sleeve 41, is separated from the developing sleeve 41 by the repulsive magnetic field of the N ₃ and N ₂ poles, and the developer T in the developing container 46 is removed. Is returned to the pool.

A DC voltage and an AC voltage are applied to the developing sleeve 41 from the power source S2. In this example, the alternating voltage (peak-to-peak potential (V _pp ) = 150
0 V, frequency (Vf) = 3000 Hz) is applied.

When an AC bias component is included in the developing bias applied to the developing device, a waveform of the AC bias, such as a sine wave, a rectangular wave, and a triangular wave, can be used as appropriate. For example, a rectangular wave voltage formed by periodically turning on / off a DC power supply can be used.

In general, in the two-component developing method, when an alternating voltage is applied, the developing efficiency is increased, and the quality of an image is high. On the contrary, there is a risk that fogging is likely to occur. Therefore, normally, the DC voltage applied to the developing device 4 and the photoconductor 1
By providing a potential difference between the surface potentials, fogging can be prevented. More specifically, a bias voltage having a potential between the potential of the exposed portion of the photoconductor 1 and the potential of the non-exposed portion is applied.

The potential difference for preventing fogging is called a fogging potential (Vback). Due to this potential difference, toner adheres to a non-image area (non-exposed portion) of the photoreceptor 1 during development on the photoreceptor 1. In addition, in a cleaner-less system, the transfer residual toner on the surface of the photoconductor 1 is also collected (simultaneous cleaning with development).

The toner concentration is monitored by a sensor (not shown) for detecting the toner concentration of the developer T in the developing container 46, and the external toner t in the developer T is consumed for developing the latent image. When the toner density falls below a predetermined density level, the replenishment toner hopper 47
6, toner is replenished. By this toner replenishing operation, the toner concentration of the developer T is constantly maintained at a predetermined level. (6) Cleanerless system The printer A of this example does not include a dedicated cleaning device (cleaner) for removing transfer residual toner remaining on the surface of the rotating photoconductor 1 after the transfer of the toner image onto the transfer material P. This is an apparatus of a cleanerless system in which the developing device 4 also serves as a cleaning unit that collects transfer residual toner remaining on the surface of the photoconductor 1. . Rotary photoconductor 1 after transfer of toner image to transfer material P
The transfer residual toner remaining on the surface is carried to the charging area n1 which is a contact portion between the photoconductor 1 and the fur brush portion 38 of the fur brush charger 3 by the subsequent rotation of the photoconductor 1. . In the charging area n1, the surface of the photoconductor 1 is rubbed by the fur brush portion 38 of the fur brush charger 3, so that the transfer residual toner carried to the charging area n1 is disturbed and moved on the surface of the photoconductor 1. As a result, the pattern at the time of the transfer remaining is scraped, and also adheres to and mixes into the fur brush portion 38 and is temporarily collected by the fur brush charger 3. . The transfer residual toner adhering to and mixed into the fur brush portion 38 of the fur brush charger 3 is regularly charged by the frictional charging with the conductive fibers constituting the fur brush portion 38, including the toner whose charge polarity is reversed. It is recharged to a polarity (negative in this example). That is, the toner is converted into a normally charged toner. . Then, the toner in the fur brush portion 38, which has been converted into the normally charged toner, is discharged onto the photoreceptor 1 by an electric repulsive force due to the charging bias applied to the fur brush charger 3. . In this manner, the toner that has been converted into the normally charged toner and discharged from the fur brush unit 38 of the fur brush charger 3 onto the photoconductor 1 is rotated by the subsequent rotation of the photoconductor 1 and the developing sleeve 41 of the developing device 4. And is collected by the developing device 4 at the fog removal potential Vback (simultaneous development cleaning).

Normally, a small amount of toner is sequentially discharged from the fur brush charger 3 as a contact charging member onto the photoreceptor 1 and is in a very thin layer in a uniformly scattered state. There is no substantial adverse effect on the exposure process. Further, generation of a ghost image due to the transfer residual toner pattern is also prevented. (7) Photoreceptor Surface Characteristics and Printing Durability Normally, toner has a relatively high electric resistance. Therefore, the adhesion and mixing of such toner particles into the contact charging member increases the electric resistance of the contact charging member. In addition, in the charging step, the control of the surface potential of the photoreceptor is impeded, which causes factors such as poor charging, image failure due to the poor charging and the like.

Among the contact charging members, the fur brush charger 3
Is preferably used in a so-called cleanerless system because the tolerance of toner mixing is relatively large.

However, when a fur brush contact charging member is used in this cleanerless system, an external additive, which is an inorganic substance carried on the surface, is also mixed into the fur brush contact charging member at the same time as the toner is mixed, and the surface of the electrophotographic photosensitive member is mixed. Rubs the photoreceptor to cause image defects and the like.

Therefore, in the present invention, the universal hardness HU is 200 N / mm ² or more (however, the curve showing the relationship between the hardness H and the indentation depth h does not have an inflection point), and By using an electrophotographic photoreceptor having a surface characteristic having a surface friction coefficient of 0.01 to 1.2, the photoreceptor is prevented from being damaged and worn due to repeated use, and the occurrence of image defects and the like is prevented. .

[0112]

Embodiments of the present invention will be described below. In this embodiment, the fur brush is used as the charging member, but it goes without saying that the same result can be obtained with a magnetic brush or a charging roller. <Example 1> (1) Production of photoreceptor By the following method, aluminum cylinder / conductive layer / subbing layer / charge generation layer / charge transport layer /
A negatively charged OPC photosensitive member comprising a surface protective layer was prepared. (I) Preparation of conductive layer Aluminum cylinder having an outer diameter of 30 mm and a length of 357.5 mm was charged with conductive titanium oxide... 10 parts by mass (tin oxide coat, number average particle diameter 0.4 μm) Phenol resin precursor ( 10 parts by weight of methanol, 10 parts by weight of butanol, 10 parts by weight of butanol.
By curing at 40 ° C, volume resistance 5 × 10 ⁹ Ω · c
m, a conductive layer having a thickness of 20 μm was provided. (Ii) Preparation of Undercoat Layer Next, the following methoxymethylated nylon (degree of methoxymethylation: about 30%) 10 parts by mass

[0113]

Embedded image (However, in the formula, m and n represent a molar ratio. The numerical value of m: n is defined by the degree of methoxymethylation.) After mixing and dissolving 150 parts by mass of isopropanol, Dip coating, 1μ
m undercoat layer was provided. (Iii) Preparation of charge generation layer Next, diffraction angle 2θ ± 0.2 in X-ray diffraction of CuKα.
° are 9.0 °, 14.2 °, 23.9 ° and 27.
4 parts by mass of TiOPc (oxytitanium phthalocyanine) having a strong peak at 1 °, 2 parts by mass of polyvinyl butyral (trade name: Eslec BM2, manufactured by Sekisui Chemical), and 60 parts by mass of cyclohexanone were treated with a sand mill using φ1 mm glass beads for 4 hours. After the dispersion, 100 parts by mass of ethyl acetate was added to prepare a dispersion for a charge generation layer. This was dip-coated on the undercoat layer obtained above to provide a 0.3 μm charge generation layer. (Iv) Preparation of charge transport layer Next, 10 parts by mass of the following triphenylamine:

[0114]

Embedded image Polycarbonate resin (bisphenol Z type, viscosity average molecular weight 20,000) ···························································································································· Dip coating on top 2
A 0 μm charge transport layer was provided. (V) Preparation of Surface Protective Layer Next, the following acrylic monomer: 30 parts by mass

[0115]

Embedded image Ultra fine particles of tin oxide having a number average particle diameter of 40 nm before dispersion: 50 parts by mass Polytetrafluoroethylene resin fine powder (number average particle size: 0.18 μm) 50 parts by mass Photopolymerization initiator , 18 parts by mass of ethanol 150 parts by mass were dispersed in a sand mill for 66 hours. This preparation was applied onto the charge transport layer by dip coating, and 200
Light curing was performed at a light intensity of W / cm ² for 60 seconds, followed by drying with hot air at 120 ° C. for 2 hours to obtain a surface protective layer. The thickness of the obtained surface protective layer was 3 μm. This photoreceptor was used as a photoreceptor A for manufacturing the following electrophotographic image forming apparatus.

The photoreceptor is rotated with respect to the surface protective layer thus produced, and # C-2 manufactured by Fuji Film
By applying pressure while contacting a 000 lapping tape, 0.1 μm polishing was performed. The photoconductor after polishing the surface protective layer is referred to as photoconductor A ′. (Vi) Measurement of Surface Characteristics The photoreceptor A ′ thus obtained was subjected to a surface film physical property test. In addition, the surface friction coefficient and the contact angle with pure water were measured. All the measurements were performed by the above-mentioned method.

As a result, the universal hardness HU was 220 N.
/ Mm ² , the coefficient of surface friction was 0.06, and the contact angle with pure water was 116 degrees. (2) Manufacture of electrophotographic image forming apparatus A laser beam printer having a structure similar to that of the electrophotographic image forming apparatus shown in FIG. 1 using a transfer type electrophotographic process, a contact charging method, a reversal developing method, and a cleanerless system. And the photoconductor A obtained in the above (1) as the photoconductor
Was provided to obtain an electrophotographic image forming apparatus of Example 1. (3) Printing durability test In order to evaluate the electrophotographic image forming apparatus of Example 1,
A copier GP55 manufactured by Canon Inc., having a structure similar to that of the electrophotographic image forming apparatus shown in FIG. 1 of the above embodiment, in which the charger is modified to a fur brush charger and the transfer device is modified to a belt transfer device. Using a device provided with the photoconductor A obtained in (1) above as a photoconductor, a printing durability test of 10,000 sheets was performed. At the time of the test, the same developer as the two-component developer composed of the externally-added toner and the magnetic carrier described in the production example in the above embodiment was used as the developer.

As a result, a good image was always obtained from the beginning to the end in a 10,000-sheet printing test. This is because the photoconductor A satisfies the above-mentioned surface characteristics of the present invention. <Embodiment 2> Photoconductor A used in the apparatus of Embodiment 1
The electrophotographic image forming apparatus of Example 2 was the same as the apparatus of Example 1 except that the photoconductor B obtained by the following method was used. (1) Production of Photoconductor B and Measurement of Surface Properties Example 1 was repeated until a conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum cylinder having an outer diameter of 30 mm and a length of 357.5 mm. Performed similarly to 1. Next, a surface protective layer was formed on the charge transport layer in the following manner. That is, the following acrylic monomer: 30 parts by mass

[0119]

Embedded image Ultrafine tin oxide particles having a number-average particle diameter of 40 nm before dispersion: 50 parts by mass Polytetrafluoroethylene resin fine powder (number-average particle size: 0.18 μm) 4 parts by mass Photopolymerization initiator , 18 parts by mass of ethanol 150 parts by mass were dispersed in a sand mill for 66 hours. This preparation was applied onto the charge transport layer by dip coating, and 200
Light curing was performed at a light intensity of W / cm ² for 60 seconds, followed by drying with hot air at 120 ° C. for 2 hours to obtain a surface protective layer. The thickness of the obtained surface protective layer was 3 μm. This photoconductor was used as a photoconductor B in the production of the following electrophotographic image forming apparatus.

The photoreceptor was rotated with respect to the surface protective layer thus produced, and a # C-2 made by Fuji Film was
By applying pressure while contacting a 000 lapping tape, 0.1 μm polishing was performed. The photoconductor after polishing the surface protective layer is referred to as photoconductor B ′.

Further, the photosensitive member B 'thus obtained
Was evaluated in the same manner as in Example 1. As a result, the universal hardness HU was 230 N / mm ² , the surface friction coefficient was 0.9, and the contact angle with pure water was 98 degrees. (2) Printing durability test Using a device in which the photoconductor B obtained in the above (1) is provided as a photoconductor, a copying machine GP55 manufactured by Canon Inc. which was remodeled in the same manner as in Example 1 above was used. A printing durability test was performed on the sheets. At the time of the test, the same developer as the two-component developer composed of the externally added toner and the magnetic carrier described in the above Production Example was used as the developer.

As a result, a good image was always obtained from the beginning to the end in a 10,000-sheet printing test. This is because the photoconductor B satisfies the above-mentioned surface characteristics of the present invention. <Embodiment 3> Photoconductor A used in the apparatus of Embodiment 1
The electrophotographic image forming apparatus of Example 3 was the same as the apparatus of Example 1 except that the photoconductor C obtained by the following method was used. (1) Production of Photoreceptor C and Measurement of Surface Properties Example 1 was repeated until a conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum cylinder having an outer diameter of 30 mm and a length of 357.5 mm. Performed similarly to 1. Next, a surface protective layer was formed on the charge transport layer in the following manner. That is, the following acrylic monomer: 30 parts by mass

[0123]

Embedded image Ultrafine tin oxide particles having a number average particle size of 40 nm before dispersion .... 50 parts by mass Polytetrafluoroethylene resin fine powder (number average particle size 0.18 μm)... 35 parts by mass Photopolymerization initiator , 18 parts by mass of ethanol 150 parts by mass were dispersed in a sand mill for 66 hours. This preparation was applied onto the charge transport layer by dip coating, and 200
Light curing was performed at a light intensity of W / cm ² for 60 seconds, followed by drying with hot air at 120 ° C. for 2 hours to obtain a surface protective layer. The thickness of the obtained surface protective layer was 3 μm. This photoreceptor was used as a photoreceptor C in the production of the following electrophotographic image forming apparatus.

The photoreceptor was rotated with respect to the surface protective layer thus produced, and a # C-2 made by Fuji Film was
By applying pressure while contacting a 000 lapping tape, 0.1 μm polishing was performed. The photoconductor after polishing the surface protective layer is referred to as photoconductor C ′.

The photosensitive member C ′ thus obtained was
Was evaluated in the same manner as in Example 1, and found that the universal hardness HU was 29 in the surface film physical property test.
0 N / mm ² , the coefficient of surface friction was 0.3, and the contact angle with pure water was 115 degrees. (2) Printing durability test Using a device provided with the photoconductor C obtained in (1) above as a photoconductor, a copying machine GP55 manufactured by Canon Inc. which was remodeled in the same manner as in Example 1 was used for 10,000. A printing durability test was performed on the sheets. At the time of the test, the same developer as the two-component developer composed of the externally added toner and the magnetic carrier described in the above Production Examples was used as the developer.

As a result, a good image was always obtained from the beginning to the end in a 10,000-sheet printing test. This is because the photoconductor C satisfies the above-mentioned surface characteristics of the present invention. <Embodiment 4> Photoconductor A used in the apparatus of Embodiment 1
The electrophotographic image forming apparatus of Example 4 was the same as the apparatus of Example 1 except that the photoconductor D obtained by the following method was used. (1) Production of Photoreceptor D and Measurement of Surface Properties Example 1 was repeated until a conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum cylinder having an outer diameter of 30 mm and a length of 357.5 mm. Performed similarly to 1. Next, a surface protective layer was formed on the charge transport layer in the following manner. That is, the same acrylic monomer as in Example 1... 30 parts by mass Tin oxide ultrafine particles having a number average particle size of 40 nm before dispersion... 50 parts by mass Polytetrafluoroethylene resin fine powder (number average 4 parts by mass 2-methylthioxanthone as a photopolymerization initiator 18 parts by mass Ethanol 150 parts by mass was dispersed in a sand mill for 66 hours. This preparation was applied onto the charge transport layer by dip coating, and 200
Light curing was performed at a light intensity of W / cm ² for 60 seconds, followed by drying with hot air at 120 ° C. for 2 hours to obtain a surface protective layer. The thickness of the obtained surface protective layer was 3 μm. This photoreceptor was used as a photoreceptor D for manufacturing the following electrophotographic image forming apparatus.

The photoreceptor was rotated with respect to the surface protective layer thus produced, and a # C-2 made by Fuji Film was
By applying pressure while contacting a 000 lapping tape, 0.1 μm polishing was performed. The photoconductor after polishing the surface protective layer is referred to as photoconductor D ′.

The photosensitive member D ′ thus obtained was
Was evaluated in the same manner as in Example 1. As a result, the universal hardness HU was 290 N / mm ² , the surface friction coefficient was 1.1, and the contact angle with pure water was 96 degrees. (2) Printing durability test Using a device in which the photoconductor D obtained in the above (1) is provided as a photoconductor in a copying machine GP55 manufactured by Canon Inc., which was remodeled in the same manner as in Example 1 above, 10,000 A printing durability test was performed on the sheets. At the time of the test, the same developer as the two-component developer composed of the externally added toner and the magnetic carrier described in the above Production Examples was used as the developer.

As a result, a good image was always obtained from the beginning to the end in a 10,000-sheet printing test. This is because the photoconductor D satisfies the above-mentioned surface characteristics of the present invention. Comparative Example 1 Photoconductor A used in the apparatus of Example 1
The electrophotographic image forming apparatus of Comparative Example 1 was the same as the apparatus of Example 1 except that was changed to the photoreceptor E obtained by the following method. (1) Production of Photoreceptor E and Measurement of Surface Properties Example 1 was repeated until a conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum cylinder having an outer diameter of 30 mm and a length of 357.5 mm. Performed similarly to 1. Next, a surface protective layer was formed on the charge transport layer in the following manner. That is, the same acrylic monomer as in Example 2 ... 30 parts by mass Tin oxide ultrafine particles having a number average particle size of 40 nm before dispersion ... 50 parts by mass Polytetrafluoroethylene resin fine powder (number average 50 parts by mass 2-methylthioxanthone as a photopolymerization initiator 18 parts by mass Ethanol 150 parts by mass was dispersed in a sand mill for 66 hours. This preparation was applied onto the charge transport layer by dip coating, and 200
Light curing was performed at a light intensity of W / cm ² for 60 seconds, followed by drying with hot air at 120 ° C. for 2 hours to obtain a surface protective layer. The thickness of the obtained surface protective layer was 3 μm. This photoconductor was used as a photoconductor E in the manufacture of the following image forming apparatus.

The photoreceptor was rotated with respect to the surface protective layer thus produced, and a # C-2 made by Fuji Film was
By applying pressure while contacting a 000 lapping tape, 0.1 μm polishing was performed. The photoconductor after polishing the surface protective layer is referred to as photoconductor E ′.

The photosensitive member E ′ thus obtained was
Was evaluated in the same manner as in Example 1. As a result, the universal hardness HU was 185 N / mm ² , the surface friction coefficient was 0.03, and the contact angle with pure water was 118 degrees. (2) Printing durability test (i) Test using a two-component developer composed of an externally added toner and a magnetic carrier The above-mentioned (1) was used as a photoreceptor in a copier GP55 manufactured by Canon Inc. which was modified in the same manner as in Example 1 above. Using the apparatus provided with the photoreceptor E obtained in (1), a printing durability test was performed on 10,000 sheets. At the time of the test, the same developer as the two-component developer composed of the externally added toner and the magnetic carrier described in the above Production Examples was used as the developer.

As a result, in the printing durability test, the photosensitive member E
The surface of the No. 1 had remarkable wear, and an image defect due to surface scratches occurred from about 1,000 sheets, and an image defect due to surface wear occurred from about 5000 sheets. This is because the photoconductor E does not satisfy the above-mentioned surface characteristics of the present invention. (Ii) Test using a two-component developer composed of a toner and a magnetic carrier without an external additive In addition, ignoring the deterioration of image quality, the two-component developer was used instead of the two-component developer composed of the external toner and the magnetic carrier. The same printing durability test as described above was carried out using the two-component developer composed of the toner particles and the magnetic carrier to which the external additives were not added at all in the externally added toners of the production examples described above.

The surface of the photoreceptor E was hardly abraded even after a 10,000-sheet printing test, but the image was inferior. After 10,000 sheets, image evaluation was performed using a two-component developer composed of the externally added toner and a magnetic carrier. As a result, a good image was obtained.

This indicates that the external additive added to the toner particles affects the abrasion of the surface of the photoreceptor. <Comparative Example 2> Photoconductor A used in the apparatus of Example 1
The electrophotographic image forming apparatus of Comparative Example 2 was the same as the apparatus of Example 1 except that was changed to the photoreceptor F obtained by the following method. (1) Production of Photoreceptor F and Measurement of Surface Properties Example 1 was repeated until a conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum cylinder having an outer diameter of 30 mm and a length of 357.5 mm. Performed similarly to 1. Next, a surface protective layer was formed on the charge transport layer in the following manner. That is, the same acrylic monomer as in Example 2 ... 30 parts by mass Tin oxide ultrafine particles having a number average particle diameter of 40 nm before dispersion ... 50 parts by mass 2-methylthioxanthone as a photopolymerization initiator ... 18 parts by mass of ethanol 150 parts by mass were dispersed in a sand mill for 66 hours. This preparation was applied onto the charge transport layer by dip coating, and 200
Light curing was performed at a light intensity of W / cm ² for 60 seconds, followed by drying with hot air at 120 ° C. for 2 hours to obtain a surface protective layer. The thickness of the obtained surface protective layer was 3 μm. This photoreceptor was used as a photoreceptor F for manufacturing the following image forming apparatus.

The photoreceptor was rotated with respect to the surface protective layer thus produced, and a # C-2 made by Fuji Film was
By applying pressure while contacting a 000 lapping tape, 0.1 μm polishing was performed. The photoconductor after polishing the surface protective layer is referred to as photoconductor F ′.

The photosensitive member F ′ thus obtained is
Was evaluated in the same manner as in Example 1. As a result, the universal hardness HU was 250 N / mm ² , but the surface friction coefficient was 1.3 and the contact angle with pure water was 90 degrees. (2) Printing endurance test Using a device in which the photoconductor F obtained in the above (1) is provided as a photoconductor in a copying machine GP55 manufactured by Canon Inc., which has been modified in the same manner as in Example 1 above, 10,000 A printing durability test was performed on the sheets. At the time of the test, the same developer as the two-component developer composed of the externally added toner and the magnetic carrier described in the above Production Examples was used as the developer.

As a result, in the printing durability test, the photosensitive member F
Abrasion occurred on the surface of the sample and image defects occurred due to surface scratches from about 5,000 sheets. This is because the photoconductor F does not satisfy the above-mentioned surface characteristics of the present invention.

The image defect due to the surface scratches is caused by the photosensitive member F
Because the surface of the surface and the smoothness of the fur brush contact charging member are low,
It is considered that the external additives mixed in the charging member are strongly pressed against the surface layer and are rubbed. <Comparative Example 3> Photoconductor A used in the apparatus of Example 1
The electrophotographic image forming apparatus of Comparative Example 3 was the same as the apparatus of Example 1 except that the photoconductor G was obtained by the following method. (1) Production of Photoconductor G and Measurement of Surface Properties Example 1 was conducted until a conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum cylinder having an outer diameter of 30 mm and a length of 357.5 mm. Performed similarly to 1. Next, a surface protective layer was formed on the charge transport layer in the following manner. That is, the same acrylic monomer as in Example 3 ... 30 parts by mass Tin oxide ultrafine particles having a number average particle size of 40 nm before dispersion ... 50 parts by mass Polytetrafluoroethylene resin fine powder (number average 200 parts by mass 2-methylthioxanthone as a photopolymerization initiator 18 parts by mass Ethanol 150 parts by mass was dispersed in a sand mill for 66 hours. This preparation was applied onto the charge transport layer by dip coating, and 200
Light curing was performed at a light intensity of W / cm ² for 60 seconds, followed by drying with hot air at 120 ° C. for 2 hours to obtain a surface protective layer. The thickness of the obtained surface protective layer was 3 μm. This photoconductor was used as a photoconductor G in the following electrophotographic image forming apparatus.

The photoreceptor was rotated with respect to the surface protective layer thus produced, and a # C-2 made by Fuji Film was
By applying pressure while contacting a 000 lapping tape, 0.1 μm polishing was performed. The photoconductor after polishing the surface protective layer is referred to as photoconductor G ′.

The photoreceptor G ′ thus obtained was obtained.
Was evaluated in the same manner as in Example 1. As a result, the universal hardness HU was 210 N / mm ² , but the surface friction coefficient was 0.007 and the contact angle with pure water was 120 degrees. (2) Printing durability test Using a device in which the photoconductor G obtained in (1) above was provided as a photoconductor, a copying machine GP55 manufactured by Canon Inc. which was remodeled in the same manner as in Example 1 above was used. A printing durability test was performed on the sheets. At the time of the test, the same developer as the two-component developer composed of the externally added toner and the magnetic carrier described in the above Production Examples was used as the developer.

As a result, in the printing durability test, a ghost image due to the transfer residual pattern was generated from the beginning. This is because the photoconductor G does not satisfy the above-mentioned surface characteristics of the present invention.

This ghost image was generated because the surface of the photosensitive member G and the fur brush contact charging member had almost no rubbing force, and the transfer residual toner could not be scraped off by the charging member. Seem.

Table 1 summarizes the surface characteristics of the photoconductors A to G obtained in Examples 1 to 4 and Comparative Examples 1 to 3 and the results of a printing durability test using the same.

[0144]

[Table 1]

[0145]

As described above, according to the present invention, in the electrophotographic photoreceptor used in a so-called cleanerless system, the surface of the photoreceptor is prevented from being scratched or abraded, whereby the photoreceptor is protected. In the electrophotographic image forming method or apparatus used, it is possible to provide an electrophotographic image forming method / apparatus capable of eliminating image defects due to scratches and abrasion, and obtaining high quality images at a small size, light weight and low cost. I can do it.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus according to the present invention.

FIG. 2 is an enlarged schematic cross-sectional view of a fur brush charger 3 in the image forming apparatus shown in FIG.

FIG. 3 is an enlarged schematic cross-sectional view of a developing device 4 in the image forming apparatus shown in FIG.

FIG. 4 is a view schematically showing a measuring device for a surface film physical property test.

FIG. 5 is a diagram illustrating an example of a relationship curve between the hardness H and the indentation depth h of the indenter in the surface film physical property test for the surface layer, where the inflection point 1 does not occur.

FIG. 6 is a diagram illustrating an example of a curve having an inflection point 1 in a relationship curve between hardness H and indentation depth h in a surface film physical property test for a surface layer.

FIG. 7 is a schematic diagram of a friction coefficient measuring instrument Hadeon 14;

FIG. 8 is a view showing a shape of a urethane rubber blade used for measuring a friction coefficient.

FIG. 9 is an enlarged view of a contact portion between a urethane rubber blade and a sample in FIG. 7;

FIG. 10 is a schematic cross-sectional view of an image forming apparatus provided with a process cartridge of the present invention using a magnetic brush charging unit as a contact charging unit.

[Explanation of symbols]

 Reference Signs List A Printer main body B Image reader 1 Photoconductor drum (image carrier) 2 Laser exposure means 3 Fur brush charger (contact charging member) 4 Developing device 5 Paper feed cassette 6 Fixing device 7 Transfer device 8 Discharge tray P Transfer material 11 Sample stand 12 Sample 13 Blade 14 Support 15 Receiving pan 16 Weight 17 Support point 18 Balancer 19 Load transducer 20 Motor 21 Holder support arm 22 Upper holder 23 Lower holder 24 Fixed screw H Hardness of surface layer h Depth of indenter o Origin 1 Inflection point in H-h curve 31 Sample 32 Sample stand 33 Indenter 34 Movable table 36 Electric-proof container 37 Core bar 38 Fur brush part 39 Electrode 41 Developing sleeve 42 Magnet roller 43, 44 Developer stirring screw 45 Control blade 46 Developing capacity 47 replenishing toner hopper portion 102 contact charging means 103 developing means 103a developing sleeve 103b magnet 105 fixing means 121 charging sleeve 122 magnet 123 the magnetic brush 200 process cartridge R transcription unit P transfer material

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Haruyuki Tsuji F-term in Canon Inc. 3-30-2 Shimomaruko, Ota-ku, Tokyo 2H003 AA00 BB11 CC04 CC06 2H005 AA08 CB07 CB13 EA05 2H068 AA04 AA08 BB31 EA43 FA27 FC01 2H077 AA37 AD02 AD06 AD13 EA03 EA11 EA15 GA01

Claims (24)

[Claims] 1. A contact charging step of charging the surface of an electrophotographic photosensitive member, an electrostatic latent image forming step of forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive member, An electrophotographic image forming method comprising: a developing step of transferring a toner carried on a toner carrier to develop the toner image into a toner image; and a transfer step of transferring the developed toner image from an electrophotographic photosensitive member to a transfer material. The developing step also serves as a cleaning step of collecting toner remaining on the electrophotographic photosensitive member after transfer; the toner has an external additive; and the electrophotographic photosensitive member has a universal hardness of HU. Is 200
N / mm ² or more (the curve showing the relationship between the hardness H and the indentation depth h has no inflection point) and the surface friction coefficient is 0.01 to 1.2. An electrophotographic image forming method having characteristics. 2. The universal hardness is 220 N / m.
The electrophotographic image forming method according to claim 1, wherein m ² or more. 3. The universal hardness is 350 N / m.
The electrophotographic image forming method according to claim 1, wherein m ² or less. 4. The surface friction coefficient is 0.02 to 1.1.
The electrophotographic image forming method according to claim 1, wherein: 5. The electrophotographic photosensitive member according to claim 1, wherein a contact angle of said surface with pure water is 95 degrees or more.
The electrophotographic image forming method according to any one of claims 1 to 4. 6. The method according to claim 5, wherein the contact angle is less than 120 degrees. 7. The electrophotographic image forming method according to claim 1, wherein the contact charging step is an injection charging step. 8. The electrophotographic image forming method according to claim 1, wherein the external additive has a number average particle size of 0.03 μm or more. 9. An electrophotographic photosensitive member, contact charging means for charging the surface of the electrophotographic photosensitive member, electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive member, Developing means for transferring the toner carried on the toner carrier to the electrostatic latent image and developing the toner image, and transfer means for transferring the developed toner image from the electrophotographic photosensitive member to a transfer material. A photographic image forming apparatus, wherein the developing unit also serves as a cleaning unit that collects toner remaining on the electrophotographic photosensitive member after transfer; the toner has an external additive; Has a universal hardness HU of 200
N / mm ² or more (the curve showing the relationship between the hardness H and the indentation depth h has no inflection point) and the surface friction coefficient is 0.01 to 1.2. An electrophotographic image forming apparatus having characteristics. 10. The universal hardness is 220 N /
The electrophotographic image forming apparatus according to claim 9, wherein the size is not less than mm ² . 11. The universal hardness is 350 N /
11. The method according to claim 9, wherein the diameter is not more than mm ^2.
2. The electrophotographic image forming apparatus according to 1. 12. The surface friction coefficient is 0.02-1.
The electrophotographic image forming apparatus according to claim 9, wherein the number is 1. 13. The electrophotographic photosensitive member according to claim 9, wherein a contact angle of the surface with pure water is 95 degrees or more.
13. The electrophotographic image forming apparatus according to claim 12. 14. The electrophotographic image forming apparatus according to claim 13, wherein the contact angle is less than 120 degrees. 15. The electrophotographic image forming apparatus according to claim 9, wherein the contact charging step is an injection charging step. 16. The electrophotographic image forming apparatus according to claim 9, wherein the external additive has a number average particle size of 0.03 μm or more. 17. An electrophotographic photoreceptor, contact charging means for charging the surface of the electrophotographic photoreceptor, electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, Developing means for transferring the toner carried on the toner carrier to the electrostatic latent image and developing the toner image, and transfer means for transferring the developed toner image from the electrophotographic photosensitive member to a transfer material. A process cartridge detachably configured from a photographic image forming apparatus, wherein the electrophotographic photosensitive member, the charging unit and the developing unit are integrally supported, and the developing unit remains on the electrophotographic photosensitive member after transfer. The toner also has an external additive, and the electrophotographic photoreceptor has a universal hardness HU of 200.
N / mm ² or more (the curve showing the relationship between the hardness H and the indentation depth h has no inflection point) and the surface friction coefficient is 0.01 to 1.2. A process cartridge having characteristics. 18. The universal hardness is 220 N /
The process cartridge according to claim 17, wherein the size is not less than mm ² . 19. The universal hardness is 350 N /
18 or less than mm ^2.
9. The process cartridge according to 8. 20. The surface friction coefficient is 0.02 to 1.
20. The process cartridge according to claim 17, wherein the number is 1. 21. A contact angle between the surface of the electrophotographic photosensitive member and pure water is 95 degrees or more.
21. The process cartridge according to any one of items 20 to 20. 22. The process cartridge according to claim 21, wherein the contact angle is less than 120 degrees. 23. The process cartridge according to claim 17, wherein the contact charging step is an injection charging step. 24. The external additive according to claim 17, wherein the external additive has a number average particle size of 0.03 μm or more.
The process cartridge according to any one of the above.