JP7328026B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus. Here, the image forming apparatus forms an image on a recording material (recording medium) using an electrophotographic image forming system. Examples of image forming apparatuses include copiers, printers (laser beam printers, LED printers, etc.), facsimile machines, word processors, and multifunction machines (multifunction printers).

2. Description of the Related Art Conventionally, organic photoreceptors have been widely used as electrophotographic photoreceptors (hereinafter also simply referred to as "photoreceptors") used in electrophotographic image forming apparatuses due to their advantages of low cost and high productivity. This is constituted by providing a photosensitive layer (organic photosensitive layer) using an organic material as a photoconductive substance (charge-generating substance or charge-transporting substance) on a support.

Since the photoreceptor is directly subjected to external electrical and mechanical forces in the steps of charging, exposure, development, transfer, and cleaning, durability against these external forces is required. Specifically, it is required to have durability against occurrence of scratches and wear on the surface due to these external forces, that is, scratch resistance and wear resistance.

However, when the abrasion of the photoreceptor is suppressed, the surface of the photoreceptor becomes difficult to refresh, and blurring of the electrostatic latent image called "image deletion" tends to occur particularly in a high humidity environment. Image deletion is mainly caused by a decrease in the surface resistance of the photoreceptor due to the adherence of discharge products such as ozone and NOx, which are generated on the surface of the photoreceptor due to charging, to the surface of the photoreceptor. do. If the friction coefficient of the surface of the photoreceptor is reduced and the hardness thereof is increased in order to suppress abrasion of the photoreceptor, the surface becomes less likely to be abraded and the discharge products adhering to the surface are less likely to be removed. As a result, the discharge products adhering to the surface of the photoreceptor absorb moisture in a high-humidity environment to lower the resistance, lower the charge retention capacity of the surface of the photoreceptor, and cause image smearing.

As a method for suppressing the occurrence of image deletion, Patent Document 1 proposes a method of adding a metal soap to a developer and supplying the metal soap from a developer carrier to the surface of a photoreceptor. In this method, zinc stearate, which is a metal soap, is supplied to the surface of the photoreceptor from a developer carrier, and the surface of the photoreceptor is coated with zinc stearate to suppress the adhesion of discharge products and prevent image deletion. preventing it from occurring.

JP-A-2005-121833

However, the metal soap supplied onto the photoreceptor by the method of Patent Document 1 is scraped off by a member such as a cleaning means that is in contact with the photoreceptor due to the rotation of the photoreceptor. In particular, the metal soap is actively supplied after the photoreceptor rotates while the developer carrier is separated from the photoreceptor, or when the amount of metal soap in the developer decreases in the latter half of the life of the developing device. There is a need. However, in the above case, the amount of metal soap applied to the surface of the photoreceptor cannot be determined, and the amount of discharge products cannot be determined, resulting in image deletion.

In view of the above situation, an object of the present invention is to provide an image forming apparatus capable of suppressing the occurrence of image deletion by supplying and maintaining metal soap on the surface of a photoreceptor at appropriate timing. be.

To achieve this object, the image forming apparatus of the present invention is an image forming apparatus for forming a toner image on a recording material, comprising a rotatable image carrier, a charging member for charging the surface of the image carrier, a metal a toner containing portion for containing toner containing soap; and a developing member for forming a toner image by supplying the toner to the surface of the image carrier charged by the charging member in the developing portion facing the image carrier. a voltage applying section for applying a charging voltage to the charging member; a current detecting section for detecting a current flowing from the charging member to the image bearing member while the charging voltage is applied to the voltage applying section; an image forming operation for forming the toner image on a recording material; and a coating operation of coating the surface of the image carrier with the metal soap by supplying toner from the developing member to the surface of the image carrier. When the current value of the current is the first current value, the coating operation is not performed, and when the current value is the second current value whose absolute value is larger than the first current value, the coating operation is performed. characterized by

According to the present invention, it is possible to suppress the occurrence of image smearing by supplying metal soap to the photoreceptor surface at appropriate timing and maintaining it.

1 is a schematic cross-sectional view of an image forming apparatus in Example 1. FIG. 4 is a cross-sectional view of the process cartridge in Example 1. FIG. 3 is a control block diagram showing a control mode of the image forming apparatus according to Embodiment 1; FIG. 4 is a control block diagram showing a control mode of a current detection unit in Example 1. FIG. 2 is a cross-sectional view of toner in Example 1. FIG. 10 is a graph of endurance transition of charging current value in Example 1. FIG. 4 is a flow chart of the metallic soap application operation in Example 1. FIG. 4 is a flow chart of the metallic soap application operation in Example 1. FIG. FIG. 11 is a control block diagram showing a control mode of a current detector in Example 2; 8 is a graph showing the relationship between the film thickness of the photoreceptor and the charging current in Example 2. FIG. FIG. 10 is a flow chart of the metallic soap applying operation in Example 2; FIG. 11 is a control block diagram showing a control mode of a current detector in Example 3; 10 is a graph showing the relationship between charging voltage and charging current depending on the environment in Example 3. FIG. FIG. 11 is a flow chart of the metallic soap application operation in Example 3; (a) It is a figure which shows the Vl increase amount in L/L environment in Example 4. FIG. (b) It is a figure which shows the Vl increase amount in H/H environment in Example 4. FIG. 10 is a graph showing the relationship between the light irradiation time to the photoreceptor and the charging current in Example 5. FIG. FIG. 11 is a flow chart of the metallic soap application operation in Example 5; FIG. 10 is a surface diagram of a photoreceptor after polishing the surface of the photoreceptor in Example 7; FIG. 11 is a schematic diagram of a polishing apparatus for polishing the surface of a photoreceptor in Example 7; FIG. 10 is a conceptual diagram of the surface layer thickness of a surface layer containing an organosilicon compound in Example 8;

Exemplary embodiments of the invention will now be described with reference to the drawings. In addition, the following embodiments are examples, and the present invention is not limited to the contents of the embodiments. Also, in the following drawings, constituent elements that are not necessary for the description of the embodiments are omitted from the drawings.

1. Image Forming Apparatus The overall configuration of the electrophotographic image forming apparatus in this embodiment will be described. FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 of Example 1. FIG. The image forming apparatus 100 of the first embodiment is a full-color laser printer that employs an in-line method and an intermediate transfer method. The image forming apparatus 100 can form a full-color image on a recording material S (for example, recording paper, plastic sheet, cloth, etc.) according to image information. Image information is input to the image forming apparatus 100 from an image reading device (not shown) connected to the image forming apparatus 100 or a host device 300 such as a personal computer communicably connected to the image forming apparatus 100 . .

Image forming apparatus 100 includes first, second, and third image forming units for forming yellow (Y), magenta (M), cyan (C), and black (K) images, respectively, as a plurality of image forming units. , and fourth image forming units SY, SM, SC, and SK.

In Embodiment 1, the image forming apparatus 100 has four drum-type electrophotographic photosensitive members (hereinafter referred to as photosensitive members 1) arranged side by side in a direction intersecting the vertical direction as a plurality of image carriers. A process cartridge 7 is formed by integrating the body 1 and the image forming section.

A photoreceptor 1 as an image carrier that carries an electrostatic latent image is rotationally driven by driving means (not shown). The charging roller 2 as a charging member is a single-layer roller composed of a conductive metal core and a conductive rubber layer, and has an outer diameter of φ7.5 mm and a volume resistivity of 10 ³ to 10 ⁶ Ω·cm. A charging voltage of -1000 V is applied to the charging roller 2 by a charging high voltage 71, which is a charging voltage applying section as a high voltage power source to be described later, so that the surface of the photoreceptor 1 is uniformly charged to -500 V. A DC (direct current) voltage of Vd+Vth is applied to the charging roller 2, and the surface of the photoreceptor 1 is uniformly charged at the charging potential Vd by discharging. Vd at this time is called a dark potential and is -500V. Vth is a discharge start voltage. When the applied charging voltage is small, the surface potential on the surface of the photoreceptor 1 does not increase due to discharge, but the surface potential starts to increase due to discharge from the discharge start voltage Vth. That is, the discharge start voltage Vth in this embodiment is -500V.

After the surface of the photoreceptor 1 is charged by the charging roller 2, the surface of the photoreceptor 1 is irradiated with laser light from an exposure unit 30 as a first exposure section. The exposure unit 30 is exposure means for forming an electrostatic latent image on the surface of the photoreceptor 1 by irradiating a laser based on image information. The surface potential of the photoreceptor 1 irradiated with the laser beam changes to -100 V as Vl, which is the light potential, and an electrostatic latent image is formed.

FIG. 2 is a cross-sectional view of the process cartridge 7 of Example 1 viewed along the longitudinal direction (rotational axis direction) of the photoreceptor 1. As shown in FIG. The process cartridge 7 is composed of the developing unit 3 and the photoreceptor unit 13 . In the developing unit 3, a developing roller 4 as a developing member and a toner supply roller (hereinafter referred to as "supply roller") 5 as a toner supply member are arranged. The developing roller 4 starts rotating in the direction of arrow D in FIG. 2, and the supply roller 5 starts rotating in the direction of arrow R in FIG. Then, a voltage of −300 V is applied as a development voltage from the development high voltage 72 as a development voltage applying section to the development roller 4, whereby an electrostatic latent image is formed on the surface of the photoreceptor 1, that is, Vl A developer (toner) is supplied to the portion by the developing roller 4 for development.

A developer image (toner image) developed on the surface of the photoreceptor 1 is transferred to the intermediate transfer belt 31 shown in FIG. An intermediate transfer belt 31 formed of an endless belt as an intermediate transfer member for transferring the toner image on the photoreceptor 1 onto the recording material S faces the photoreceptor 1 of each image forming section. It abuts on the photoreceptor 1 of the forming portion and circulates (rotates) in the direction of arrow B (counterclockwise) in FIG.

Primary transfer rollers 32 , which are transfer members as primary transfer means, are arranged on the inner peripheral surface side of the intermediate transfer belt 31 so as to face the photoreceptors 1 . A primary transfer voltage power supply (primary transfer high voltage) 73 serving as a primary transfer voltage applying section applies a voltage having a polarity opposite to the normal charging polarity of the toner to the primary transfer roller 32 . As a result, the toner image on the photosensitive member 1 is transferred (primary transfer) onto the intermediate transfer belt 31 . As for the polarity of the toner in the present embodiment, the normal polarity is the negative polarity. Therefore, primary transfer can be performed by applying a positive voltage as the primary transfer voltage.

A secondary transfer roller 33 as a secondary transfer unit is arranged on the outer peripheral surface side of the intermediate transfer belt 31 . A voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 33 from a secondary transfer voltage power supply (secondary transfer high voltage) 74 as a secondary transfer voltage applying section. As a result, the toner image on the intermediate transfer belt 31 is transferred to the recording material S (secondary transfer). For example, when forming a full-color image, the above process is sequentially performed in the image forming stations SY, SM, SC, and SK, and the toner images of each color are sequentially superimposed and primary transferred onto the intermediate transfer belt 31 . After that, the recording material S is conveyed to the secondary transfer portion in synchronization with the movement of the intermediate transfer belt 31 . Then, the four-color toner images on the intermediate transfer belt 31 are collectively secondary-transferred onto the recording material S by the action of the secondary transfer roller 33 which is in contact with the intermediate transfer belt 31 via the recording material S. be.

The recording material S onto which the toner image has been transferred is conveyed to the fixing device 34 . By applying heat and pressure to the recording material S in the fixing device 34 , the toner image is fixed on the recording material S, and the recording material S is discharged outside the image forming apparatus 100 .

On the other hand, the surface potential of the photoreceptor 1 after transferring the toner onto the intermediate transfer belt 31 is non-uniform due to the primary transfer voltage. Therefore, by exposing the entire surface of the photoreceptor 1 (to irradiate the entire surface with light) in the pre-exposure unit 27, which is pre-exposure means as a second exposure section, the surface of the photoreceptor 1 that has become uneven due to the previous image formation is exposed. Even out the surface potential. That is, the surface of the photoreceptor 1 is irradiated with light so as to remove residual charges on the surface of the photoreceptor 1 . The pre-exposure unit 27 is located downstream of the transfer unit, which is the contact position between the intermediate transfer belt 31 and the photoreceptor 1, in the rotation direction of the photoreceptor 1, and from the charging unit, which is the contact position between the charging roller 2 and the photoreceptor 1. is disposed between the photoreceptors 1 on the upstream side in the rotational direction, and exposes the surface of the photoreceptor 1, which is the opposing portion. As a light source for the pre-exposure unit 27, an LED, a halogen lamp, or the like can be used. Although the light source to be used is not particularly limited, it is preferable to use an LED from the viewpoint of low driving voltage and easy miniaturization of the device.

Further, the toner remaining on the surface of the photoreceptor 1 without being transferred by the primary transfer roller 32 is scraped off from the surface of the photoreceptor 1 by the cleaning blade 8 in contact with the photoreceptor 1, and is provided below the cleaning blade 8. The toner is stored in the waste toner storage chamber 9 . Toner remaining on the intermediate transfer belt 31 without being transferred onto the recording material S by the secondary transfer roller 33 is conveyed to an intermediate transfer member cleaning device 35 as a cleaning device and removed.

2. Control Mode of Image Forming Apparatus FIG. 3 is a block diagram showing a schematic control mode of the main part of the image forming apparatus 100 in this embodiment. FIG. 4 is a diagram showing a mode related to control of the current detecting section 36 as charging current detecting means, which is a feature of this embodiment. A control unit 202 is means for controlling the operation of the image forming apparatus 100, and transmits and receives various electrical information signals. It also processes electrical information signals input from various process equipment and sensors, and processes command signals to various process equipment. The controller 200 exchanges various electrical information with the host apparatus, and controls the image forming operation of the image forming apparatus 100 by the control unit 202 via the interface 201 according to a predetermined control program and reference table. control effectively. The control unit 202 has a CPU 155 which is a central element that performs various arithmetic processing, and is configured by being connected to the RAM and ROM 33 as storage elements, the memory 15 as storage means, and the like. In addition, a judgment unit 156 is provided for judging whether or not the metal soap applying operation, which will be described later, can be executed, according to the value of the charging current that flows when the charging voltage is applied. The RAM stores sensor detection results, counter count results, calculation results, and the like, and the ROM 33 stores control programs, data tables obtained in advance through experiments, and the like. Control objects, sensors, counters, and the like in the image forming apparatus 100 are connected to the control unit 202 . A control unit 202 controls the transmission and reception of various electrical information signals, the timing of driving each unit, and the like, thereby controlling a predetermined image forming sequence. For example, in order to form a toner image on the surface of the photoreceptor 1, the following high voltage power supply and devices are controlled. A charging high voltage 71 as a charging power source, a developing high voltage 72 as a developing power source, a supply high voltage 75 as a power source for the supply roller 5 that supplies the toner supply voltage, a developing blade high voltage 76 as a power source for the developing blade 6 as a toner regulating member, and exposure. It controls the unit 30 and the like. Further, a primary transfer high voltage 73 as a primary transfer power source for forming a toner image on the recording material S, a secondary transfer high voltage 74 as a secondary transfer power source, It controls the exposure unit 27 and the like. In addition, it controls the contact/separation mechanism 50 that controls the contact/separation between the developing roller 4 and the photoreceptor 1 . In this embodiment, the control unit 202 controls the high pressure and the like in order to perform the metallic soap coating operation, which will be described later in detail.

In this embodiment, the process cartridge 7 is provided with a memory 15 as a storage unit. As the memory 15, any form such as a contact non-volatile memory, a non-contact non-volatile memory, and a volatile memory having a power source can be used. In Example 1, the non-contact non-volatile memory 15 is mounted on the process cartridge 7 . The non-contact non-volatile memory 15 has an antenna (not shown) as information transmission means on the memory side, and can read and write information by wirelessly communicating with the CPU 155 provided in the main body of the image forming apparatus 100 . is. In the first embodiment, the CPU 155 has the functions of information transmission means on the main body side of the image forming apparatus 100 and reading/writing means of information in the memory 15 . The memory 15 stores an initial charging current value and a threshold of the charging current value, which will be described later.

3. Schematic Configuration of Process Cartridge The overall configuration of the process cartridge 7 installed in the image forming apparatus 100 of the first embodiment will be described in detail with reference to FIG. The process cartridge 7 is attachable to and detachable from the image forming apparatus 100 via a mounting means such as a mounting guide and a positioning member (not shown) provided in the image forming apparatus 100 . In Embodiment 1, the process cartridges 7 for each color have the same shape, and the process cartridges 7 for each color contain yellow (Y), magenta (M), cyan (C), black (K), respectively. ) are stored therein. Although the process cartridge 7 will be described in the first embodiment, the developing unit 3 may be configured to have a developing cartridge that can be attached to and detached from the image forming apparatus 100 by itself.

In Embodiment 1, the configuration and operation of the process cartridges 7 for each color are substantially the same except for the type (color) of the toner 10 contained therein.

The process cartridge 7 has a developing unit 3 having a developing roller 4 and the like and a photoreceptor unit 13 having the photoreceptor 1 .

In the present embodiment, the developing unit 3 and the photosensitive member unit 13 are integrated into the process cartridge 7, but the present invention is not limited to this. .

The developing unit 3 is roughly divided into a developing chamber 3a and a toner container 3b. A toner conveying member 22 for conveying the toner 10 to the developing chamber 3a is provided in the toner containing portion 3b. there is

The developing chamber 3a is provided with a developing roller 4 as a toner carrying member that contacts the photoreceptor 1 and rotates in the direction of arrow D in the figure. In Example 1, the developing roller 4 and the photoreceptor 1 rotate so that their surfaces move in the same direction in the developing portions facing each other.

Further, inside the developing chamber 3a, there are provided a supply roller 5 for supplying the developing roller 4 with the toner 10 conveyed from the toner containing portion 3b, and a coating amount control roller for the toner 10 supplied from the supply roller 5 onto the developing roller 4. and a toner regulating member 6 for imparting electric charge.

Independent voltages are applied to the developing roller 4, the supply roller 5, and the toner regulating member 6 from a high-voltage power supply. The toner 10 supplied to the developing roller 4 by the supplying roller 5 is triboelectrically charged by rubbing between the developing roller 4 and the toner regulating member 6, and the layer thickness is regulated at the same time as being charged. The regulated toner 10 on the developing roller 4 is conveyed to the portion facing the photoreceptor 1 by the rotation of the developing roller 4, and the electrostatic latent image on the photoreceptor 1 is developed and visualized as a toner image.

In the present invention, the prescribed DC voltage (development voltage: Vdc) applied to the developing roller 4 is -300V. Further, by applying a voltage (supply voltage: Vr=−250 V) to the supply roller 5, the potential difference (ΔVr) between the supply roller 5 and the developing roller 4 is adjusted, and the amount of toner 10 supplied to the developing roller 4 is adjusted. can be adjusted. In this embodiment, ΔVr=Vdc-Vr is set to -50V.

In the first embodiment, when the electrostatic latent image on the photoreceptor 1 is developed and visualized as a toner image, the developing roller 4 is rotationally driven so as to be in contact with the peripheral surface of the photoreceptor 1 . This is for the purpose of facilitating the supply of metal soap externally added to the toner, which will be described later, onto the photoreceptor 1 . However, the structure is not limited to the structure in which the developing roller 4 and the photoreceptor 1 are in contact with each other as long as the structure can supply metallic soap.

Here, in the following description, with respect to the potential and applied voltage, a large absolute value on the negative side (for example, -1000 V for -500 V) is referred to as a high potential, and a small absolute value on the negative side ( For example, -300V for -500V) is called a low potential. This is because the normal polarity of the negatively charged toner 10 in this embodiment is taken as a reference.

Also, the voltage in this embodiment is expressed as a potential difference from the ground potential (0 V). Therefore, the development voltage of -300 V is interpreted as having a potential difference of -300 V with respect to the ground potential due to the development voltage applied to the core metal of the development roller 4 . This is the same for other voltages such as charging voltage.

The photosensitive member 1 is rotatably attached to the photosensitive member unit 13 via a bearing (not shown). Photoreceptor 1 is rotationally driven in the direction of arrow A in FIG. 2 by receiving the driving force of a drive motor (not shown). A charging roller 2 and a cleaning blade 8 as a plate-shaped elastic member are arranged in the photoreceptor unit 13 so as to be in contact with the peripheral surface of the photoreceptor 1 . One end of the cleaning blade 8 is fixed to a plate-like metal plate, and the other free end abuts against the photoreceptor 1 to form a cleaning nip, which is a contact portion with the photoreceptor 1 . By rubbing the surface of the photoreceptor 1 with a cleaning blade 8 to scrape off the toner 10 and fine particles remaining in the transfer process and storing them in the waste toner storage chamber 9, contamination of the charging roller 2 and toner on the photoreceptor 1 can be prevented. 10 to prevent image damage due to the accompanying rotation.

4. Structure of Photoreceptor In the present embodiment, the electrophotographic photoreceptor 1 has a support. The support is preferably a conductive support having electrical conductivity. Further, the shape of the support includes a cylindrical shape, a belt shape, a sheet shape, and the like. Among them, a cylindrical support is preferable. Further, the surface of the support may be subjected to electrochemical treatment such as anodization, blasting treatment, cutting treatment, or the like.

The material of the support is preferably metal, resin, glass, or the like. Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among them, an aluminum support using aluminum is preferable. Conductivity may also be imparted to the resin or glass by treatment such as mixing or coating with a conductive material.

In this embodiment, an aluminum cylinder (JIS-A3003, aluminum alloy) having a diameter of 24 mm and a length of 257.5 mm was used as the support (conductive support). In this embodiment, a conductive layer may be provided on the support. By providing the conductive layer, it is possible to cover scratches and irregularities on the surface of the support and to control reflection of light on the surface of the support.

In this embodiment, a conductive layer may be provided on the support. By providing the conductive layer, it is possible to cover scratches and irregularities on the surface of the support and to control reflection of light on the surface of the support. The conductive layer preferably contains conductive particles and a resin. Materials for the conductive particles include metal oxides, metals, and carbon black. Metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, and bismuth oxide. Metals include aluminum, nickel, iron, nichrome, copper, zinc, silver and the like.

Among these, metal oxides are preferably used as the conductive particles, and titanium oxide, tin oxide, and zinc oxide are particularly preferably used.

When a metal oxide is used as the conductive particles, the surface of the metal oxide may be treated with a silane coupling agent or the like, or the metal oxide may be doped with an element such as phosphorus or aluminum or an oxide thereof.

Also, the conductive particles may have a laminated structure including core particles and a coating layer that covers the particles. Examples of core material particles include titanium oxide, barium sulfate, and zinc oxide. Metal oxides, such as tin oxide, are mentioned as a coating layer.

Moreover, when a metal oxide is used as the conductive particles, the volume average particle diameter thereof is preferably 1 nm or more and 500 nm or less, more preferably 3 nm or more and 400 nm or less.

Examples of resins include polyester resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenol resins, and alkyd resins.

In addition, the conductive layer may further contain silicone oil, resin particles, masking agents such as titanium oxide, and the like.

The average film thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

The conductive layer can be formed by preparing a conductive layer coating liquid containing each of the above materials and a solvent, forming a coating film thereon, and drying the coating film. Solvents used in the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents and the like. Examples of the dispersion method for dispersing the conductive particles in the conductive layer coating liquid include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

In this example, the following materials were prepared.
・214 parts of titanium oxide (TiO ₂ ) particles (average primary particle size: 230 nm) coated with oxygen-deficient tin oxide (SnO ₂ ) as metal oxide particles ・Phenolic resin (monomer of phenolic resin) as binding material / Oligomer) (trade name: Pryofen J-325, manufactured by Dainippon Ink and Chemicals, Inc., resin solid content: 60 mass%) 132 parts 1-methoxy-2-propanol 98 parts as a solvent, diameter 0 450 parts of glass beads of .8 mm Placed in a sand mill using these, rotation speed: 2000 rpm,
Dispersion treatment time: 4.5 hours, setting temperature of cooling water: 18°C, dispersion treatment was performed to obtain a dispersion liquid. The glass beads were removed from this dispersion with a mesh (opening: 150 μm). Subsequently, silicone resin particles (trade name: Tospearl 120, manufactured by Momentive Performance Materials Co., Ltd., average particle size 2 μm) were added to the dispersion as a surface roughening agent. The amount of the silicone resin particles added was adjusted to 10% by mass with respect to the total mass of the metal oxide particles and the binder material in the dispersion after removing the glass beads. In addition, silicone oil (trade name: SH28PA, manufactured by Dow Corning Toray Co., Ltd.) was added as a leveling agent to 0.01% by mass with respect to the total mass of the metal oxide particles and the binder in the dispersion. ) was added to the dispersion. Next, a mixed solvent of methanol and 1-methoxy-2-propanol (mass ratio 1:1) was added to the dispersion and stirred to prepare a conductive layer coating liquid. The amount of the mixed solvent to be added is such that the total mass of the metal oxide particles, the binder material and the surface roughening imparting agent in the dispersion (that is, the mass of the solid content) is 67% by mass with respect to the mass of the dispersion. made it This conductive layer coating solution was applied onto a support by dip coating and heated at 150° C. for 30 minutes to form a conductive layer having a thickness of 30.0 μm.

In this embodiment, an undercoat layer may be provided over the support or conductive layer. By providing the undercoat layer, the adhesion function between the layers is enhanced, and the charge injection blocking function can be imparted. The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of resins include polyester resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, epoxy resins, melamine resins, polyurethane resins, phenol resins, polyvinyl phenol resins, alkyd resins, polyvinyl alcohol resins, polyethylene oxide resins, polypropylene oxide resins, and polyamide resins. , polyamic acid resins, polyimide resins, polyamideimide resins, cellulose resins, and the like.

The polymerizable functional group possessed by the monomer having a polymerizable functional group includes an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, Carboxylic anhydride groups, carbon-carbon double bond groups, and the like.

In addition, the undercoat layer may further contain an electron transporting substance, metal oxide, metal, conductive polymer, etc. for the purpose of enhancing electrical properties. Among these, electron transport substances and metal oxides are preferably used.

Examples of electron-transporting substances include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds, and boron-containing compounds. . An electron transporting substance having a polymerizable functional group may be used as the electron transporting substance, and an undercoat layer may be formed as a cured film by copolymerizing the electron transporting substance with the above-mentioned monomer having a polymerizable functional group.

Metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, and silicon dioxide. Examples of metals include gold, silver, and aluminum.

In addition, the undercoat layer may further contain additives.

The average film thickness of the undercoat layer is preferably from 0.1 μm to 50 μm, more preferably from 0.2 μm to 40 μm, and particularly preferably from 0.3 μm to 30 μm.

The undercoat layer can be formed by preparing an undercoat layer coating solution containing each of the materials and solvents described above, forming a coating film, and drying and/or curing the coating film. Solvents used in the coating liquid include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents and the like.

In this example, the following materials were prepared.
4 parts of an electron-transporting substance represented by the following formula (E) Block isocyanate (trade name: Duranate SBN-70D, manufactured by Asahi Kasei Chemicals Co., Ltd.) 5.5 parts Polyvinyl butyral resin (S-Lec KS-5Z, Sekisui Chemical Co., Ltd.) 0.3 parts of zinc hexanoate (manufactured by Mitsuwa Chemicals Co., Ltd.) and 0.05 parts of zinc hexanoate (manufactured by Mitsuwa Chemicals Co., Ltd.) as a catalyst. A coating liquid for an undercoat layer was prepared by dissolving in a mixed solvent. This undercoat layer coating liquid was dip-coated on the conductive layer and heated at 170° C. for 30 minutes to form an undercoat layer having a thickness of 0.7 μm.

Next, the charge generation layer will be described. The charge generation layer preferably contains a charge generation substance and a resin.

Examples of charge-generating substances include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferred. Among the phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred.

The content of the charge-generating substance in the charge-generating layer is preferably 40% by mass or more and 85% by mass or less, more preferably 60% by mass or more and 80% by mass or less, relative to the total mass of the charge-generating layer. preferable.

Resins include polyester resins, polycarbonate resins, polyvinyl acetal resins, polyvinyl butyral resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenol resins, polyvinyl alcohol resins, cellulose resins, polystyrene resins, and polyvinyl acetate resins. , polyvinyl chloride resin, and the like. Among these, polyvinyl butyral resin is more preferable.

The charge generation layer may further contain additives such as antioxidants and UV absorbers. Specific examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, and the like.

The average film thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, more preferably 0.15 μm or more and 0.4 μm or less.

The charge-generating layer can be formed by preparing a charge-generating layer coating solution containing the above materials and a solvent, forming a coating film, and drying the coating film. Solvents used in the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents and the like.

In this example, 10 parts of crystalline hydroxygallium phthalocyanine having peaks at 7.5° and 28.4° in a chart obtained by CuKα characteristic X-ray diffraction and polyvinyl butyral resin (trade name: S-Lec BX) -1, manufactured by Sekisui Chemical Co., Ltd.) was prepared. These were added to 200 parts of cyclohexanone and dispersed for 6 hours using a sand mill apparatus using glass beads with a diameter of 0.9 mm. 150 parts of cyclohexanone and 350 parts of ethyl acetate were further added to dilute the mixture to obtain a charge generation layer coating solution. got The resulting coating liquid was dip-coated on the undercoat layer and dried at 95° C. for 10 minutes to form a charge generation layer having a thickness of 0.20 μm. The X-ray diffraction measurement was performed under the following conditions.

[Powder X-ray diffraction measurement]
Measuring machine used: Rigaku Denki Co., Ltd., X-ray diffractometer RINT-TTRII
X-ray tube: Cu
Tube voltage: 50KV
Tube current: 300mA
Scanning method: 2θ/θ scan Scanning speed: 4.0°/min
Sampling interval: 0.02°
Start angle (2θ): 5.0°
Stop angle (2θ): 40.0°
Attachment: Standard sample holder Filter: Not used Incident monochrome: Used Counter monochromator: Not used Divergence slit: Open Vertical divergence limiting slit: 10.00 mm
Scattering slit: open Receiving slit: open Flat plate monochromator: used Counter: scintillation counter Next, the charge transport layer will be described. The charge transport layer is the surface layer in this example. The charge transport layer preferably contains a charge transport material and a resin. Examples of charge-transporting substances include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. be done. Among these, triarylamine compounds and benzidine compounds are preferred.

Examples of resins include polyester resins, polycarbonate resins, acrylic resins, and polystyrene resins. Among these, polycarbonate resins and polyester resins are preferred. A polyarylate resin is particularly preferable as the polyester resin.

When the charge transport layer is not the surface layer, the content of the charge transport substance in the charge transport layer is preferably 25% by mass or more and 70% by mass or less, preferably 30% by mass or more, based on the total mass of the charge transport layer. It is more preferably 55% by mass or less. The content ratio (mass ratio) of the charge transport substance and the resin is preferably 4:10 to 20:10, more preferably 5:10 to 12:10.

The charge transport layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipperiness agents and wear resistance improvers. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, boron nitride particles. etc.

The average film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less.

The charge-transporting layer can be formed by preparing a charge-transporting-layer coating solution containing each of the materials and solvents described above, forming a coating film thereon, and drying the coating film. Solvents used in the coating liquid include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Among these solvents, ether solvents and aromatic hydrocarbon solvents are preferred.

In this example, the following materials were prepared.
・6 parts of a compound represented by the following formula (C-1) (charge-transporting substance (hole-transporting compound)) ・6 parts of a compound represented by the following formula (C-2) (charge-transporting substance (hole-transporting compound)) 3 parts Compound represented by the following formula (C-3) (charge-transporting substance (hole-transporting compound)) 1 part Polycarbonate (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering-Plastics Co., Ltd.) 10 parts ( 0.02 parts of a polycarbonate resin having copolymer units of C-4) and (C-5) (x/y = 9/1: Mw = 20000)
By dissolving these in a mixed solvent of 25 parts of o-xylene/25 parts of methyl benzoate/25 parts of dimethoxymethane, a coating solution for charge transport layer was prepared. The charge transport layer coating liquid was applied onto the charge generation layer by dip coating to form a coating film, and the coating film was dried at 120° C. for 30 minutes to form a charge transport layer having a thickness of 16 μm.

Photoreceptor a was thus produced as a cylindrical (drum-shaped) photoreceptor 1 having a support, an undercoat layer, a charge generation layer, and a charge transport layer in this order.

As described above, the photoreceptor 1 of this embodiment includes a cylindrical conductive metal support, a conductive layer as an undercoat layer of the support, and a photosensitive layer (charge generating layer) formed on the undercoat layer. layer, charge transport layer). The photoreceptor 1 is composed of a photosensitive material such as OPC (organic photo-semiconductor), amorphous selenium, amorphous silicon, etc., provided on a drum substrate on a cylinder made of aluminum, nickel or the like and having an outer diameter of φ24 mm as a support. It is.

5. Structure of Toner FIG. 5 shows a schematic diagram of the toner 10 used in Example 1. As shown in FIG. In Example 1, the inorganic particle externally added toner 45 is used in which the inorganic silicon 45b is externally added to the mother particles 45a to secure fluidity and improve chargeability. The toner used in Example 1 is a non-magnetic one-component particle-polymerized toner having a negatively charged polarity, and has an average particle size of 7 μm.

Furthermore, in addition to the inorganic silicon 45b, a metallic soap 45c is externally added for the purpose of suppressing image deletion. By supplying the metal soap 45c to the photosensitive member 1 to form a protective film, it is possible to reduce adhesion of discharge products and the like. When the discharge product contains moisture, the resistance decreases. Therefore, the surface of the photoreceptor 1 to which the discharge products adhere has a low resistance. By supplying the metal soap 45c to the surface of the photoreceptor 1, it is possible to suppress the occurrence of image deletion caused by the surface resistance of the photoreceptor 1 being lowered.

Metal soap 45c is a general term for long-chain fatty acids and metal salts other than sodium and potassium. Specific examples include metal salts of fatty acids such as stearic acid, myristic acid, lauric acid, ricinoleic acid, and octylic acid and metal species such as lithium, magnesium, calcium, barium, and zinc. Good to use. In Example 1, zinc stearate is externally added as the metal soap 45c. The types of metal soap 45c are not limited to these, and lead stearate, cadmium stearate, barium stearate, calcium stearate, aluminum stearate, zinc stearate, magnesium stearate, zinc laurate, and myristine. Zinc acid or the like can also be used as appropriate. The external addition amount of the metal soap 45c is desirably 0.6 wt % or less. The greater the amount of the external additive added, the more effective it is in suppressing the image flow. This is a phenomenon called solid follow-up failure, in which follow-up performance deteriorates toward the trailing edge when outputting a solid black image. The average particle diameter of the metal soap 45c is preferably 0.15 μm or more and 2.0 μm or less. If the average particle diameter of the metal soap 45c is smaller than 0.15 μm, it becomes difficult to apply it to the surface of the photoreceptor 1 . In particular, it becomes noticeable when the surface of the photoreceptor 1, which will be described later, has grooves. On the other hand, if the particle size is larger than 2.0 μm, the toner cannot pass through the toner regulating member 6 in the developing unit 3 and is left behind in the developing chamber 3 a , making it difficult to supply the surface of the photoreceptor 1 .

A method for measuring the average particle size of the metal soap 45c will be described. 10 mL of ethanol was added to 0.5 g of metallic soap 45c, and ultrasonically dispersed for 5 minutes using an ultrasonic disperser manufactured by Nippon Seiki Co., Ltd. Next, ethanol is circulated as a measurement solvent. Then, the obtained dispersion of metallic soap 45c was measured on a Microtrac Laser Diffraction/Scattering Particle Size Distribution Analyzer (SPA type) manufactured by Nikkiso Co., Ltd. DV (diffracted light amount), which is a value related to the integrated value of scattered light amount of particles, was measured. Add until the value is 0.6-0.8. Then, the particle size distribution in this state was measured, and the median diameter obtained as the cumulative median diameter of 50% diameter was taken as the average particle diameter.

The metal soap 45c having the above average particle diameter may be produced, for example, by using a double decomposition method in which a fatty acid salt aqueous solution and an inorganic metal salt aqueous solution or dispersion are allowed to react.

In this example, zinc stearate having an average particle size of 0.60 μm was used. Zinc stearate as the metal soap 45c is attached to the toner particles by being charged to the opposite polarity of the toner, and supplied onto the photoreceptor 1 during non-image formation.

Next, a method for producing toner particles will be described. A known means can be used as a method for producing toner particles, and a kneading pulverization method or a wet production method can be used. A wet production method is preferable from the viewpoint of uniformity of particle size and shape controllability. Furthermore, as the wet production method, a suspension polymerization method, a dissolution suspension method, an emulsion polymerization aggregation method, an emulsion aggregation method, or the like may be used.

In this example, a suspension polymerization method will be described. In the suspension polymerization method, first, a polymerizable monomer for forming a binder resin and, if necessary, other additives such as a colorant are added using a dispersing machine such as a ball mill or an ultrasonic dispersing machine. A polymerizable monomer composition is prepared by uniformly dissolving or dispersing these components. This step is referred to as a step of preparing a polymerizable monomer composition. At this time, if necessary, a polyfunctional monomer, a chain transfer agent, a wax as a release agent, a charge control agent, a plasticizer, and the like can be appropriately added. As the polymerizable monomer in the suspension polymerization method, the following vinyl-based polymerizable monomers can be preferably exemplified.

Styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, p- styrene derivatives such as n-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene; methyl acrylate; , ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n - acrylic polymerizable monomers such as nonyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethyl phosphate ethyl acrylate, diethyl phosphate ethyl acrylate, dibutyl phosphate ethyl acrylate, 2-benzoyloxyethyl acrylate; methyl methacrylate, ethyl methacrylate , n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate , diethyl phosphate ethyl methacrylate, methacrylic polymerizable monomers such as dibutyl phosphate ethyl methacrylate; methylene aliphatic monocarboxylic acid esters; vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, vinyl benzoate, vinyl esters such as vinyl formate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropyl ketone.

Next, the polymerizable monomer composition is put into an aqueous medium prepared in advance, and droplets of the polymerizable monomer composition are formed by a stirrer or a disperser having a high shear force. Form the desired toner particle size. This process is called a granulation process. It is preferable that the aqueous medium in the granulation step contains a dispersion stabilizer in order to control the particle size of the toner particles, sharpen the particle size distribution, and suppress coalescence of the toner particles in the production process. Dispersion stabilizers are generally classified broadly into macromolecules that generate a repulsive force due to steric hindrance and poorly water-soluble inorganic compounds that stabilize dispersion by electrostatic repulsive force. Fine particles of poorly water-soluble inorganic compounds are preferably used because they dissolve in acids or alkalis and can be dissolved and easily removed by washing with acids or alkalis after polymerization.

As the dispersion stabilizer for the sparingly water-soluble inorganic compound, one containing any one of magnesium, calcium, barium, zinc, aluminum and phosphorus is preferably used. More preferably, one of magnesium, calcium, aluminum and phosphorus is desired. Specifically, the following are mentioned.

Magnesium phosphate, tricalcium phosphate, aluminum phosphate, zinc phosphate, magnesium carbonate, calcium carbonate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, hydroxyapatide.

Organic compounds such as polyvinyl alcohol, gelatin, methyl cellulose, methylhydroxypropyl cellulose, ethyl cellulose, sodium salts of carboxymethyl cellulose, and starch may be used in combination with the dispersion stabilizer. It is preferable to use 0.01 parts by mass or more and 2.00 parts by mass or less of these dispersion stabilizers with respect to 100 parts by mass of the polymerizable monomer.

Furthermore, in order to make these dispersion stabilizers finer, 0.001 parts by mass or more and 0.1 parts by mass or less of a surfactant may be used together with 100 parts by mass of the polymerizable monomer. Specifically, commercially available nonionic, anionic, and cationic surfactants can be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate and calcium oleate are preferably used.

After the granulation step or while performing the granulation step, the temperature is preferably set to 50° C. or higher and 90° C. or lower to polymerize the polymerizable monomer contained in the polymerizable monomer composition to obtain a toner. A particle dispersion is obtained. This process is called a polymerization process. In the polymerization step, it is preferable to perform a stirring operation so that the temperature distribution in the container becomes uniform. When the polymerization initiator is added, it can be added at any desired timing and required time. Further, in order to obtain a desired molecular weight distribution, the temperature may be raised in the second half of the polymerization reaction, and further, in order to remove unreacted polymerizable monomers, by-products, etc. from the system, the second half of the reaction or the end of the reaction may be heated. Afterwards, a portion of the aqueous medium may be distilled off by a distillation operation. The distillation operation can be performed under normal pressure or reduced pressure.

An oil-soluble initiator is generally used as the polymerization initiator used in the suspension polymerization method. For example:

2,2'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4 - azo compounds such as methoxy-2,4-dimethylvaleronitrile; acetylcyclohexylsulfonyl peroxide, diisopropyl peroxycarbonate, decanonyl peroxide, lauroyl peroxide, stearoyl peroxide, propionyl peroxide, acetyl peroxide, tert- Butyl peroxy-2-ethylhexanoate, benzoyl peroxide, tert-butyl peroxyisobutyrate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, tert-butyl hydroperoxide, di-tert-butylperoxide peroxide initiators such as oxide, tert-butyl peroxypivalate and cumene hydroperoxide;

If necessary, a water-soluble initiator may be used in combination with the polymerization initiator, and examples thereof include the following.

ammonium persulfate, potassium persulfate, 2,2'-azobis(N,N'-dimeleneisobutyroamidine) hydrochloride, 2,2'-azobis(2-aminodinopropane) hydrochloride, azobis(isobutylamidine) hydrochloride, sodium 2,2'-azobisisobutyronitrile sulfonate, ferrous sulfate or hydrogen peroxide.

These polymerization initiators can be used singly or in combination, and in order to control the degree of polymerization of the polymerizable monomer, a chain transfer agent, a polymerization inhibitor, etc. can be further added and used.

The amount of inorganic silica transferred to washing was measured using a Henschel mixer (manufactured by Nippon Coke Kogyo Co., Ltd.), and the amount of external additive added, which is the external additive condition, the rotational speed (peripheral speed) of the tip of the spatter, and the rotational speed of the spatter. I coped by changing the time (time) that I was there. Table 1 below shows external additive conditions for the toner a. The details of the peripheral speed and time, which are the external addition conditions, are as described in JP-A-2016-38591. Further, 0.20 wt % of zinc stearate was externally added to the toner a used in this example.

6. Effect of Discharge Products on Photoreceptor When an image forming operation is performed using the image forming apparatus 100 , if the charging roller 2 is discharged, discharge products such as ozone and NOx are generated. May adhere to surfaces. The discharge products are scraped off by the cleaning blade 8 or the like in contact with the photoreceptor 1. If the amount of adhered products is larger than the amount of scraping off, the discharge products are gradually accumulated on the surface of the photoreceptor 1 by repeated image forming operations. go. In the contact charging method, the amount of discharge is smaller than that in the corona charging method using a corona charger, and the amount of discharge products generated is small. However, since the position where the discharge products are generated is the minute gap between the photoreceptor 1 and the charging roller 2, even if the amount of discharge products generated is small, the discharge products adhere to the surface of the photoreceptor 1. It's easy to do. When the discharge product adheres to the surface of the photoreceptor 1, it absorbs moisture and the electrical resistance of the surface of the photoreceptor 1 decreases. The decrease in resistance affects the potential formation on the photoreceptor 1 by the discharge by the charging roller 2, and the desired Vd and Vl cannot be formed. As a result, image formation cannot be properly performed, and image defects occur. Main image defects include white spots caused by latent image dullness in part or all of an image, outline blurring at image boundaries, and fogging due to potential deviation.

As for image deletion, when abrasion of the photoreceptor 1 is suppressed, the surface of the photoreceptor 1 becomes difficult to refresh, and blurring of an electrostatic latent image tends to occur particularly in a high-humidity environment. If the abrasion rate is 0.05 μm/1000 sheets or less, image deletion is likely to occur.

Therefore, in order to reduce the influence of the discharge products, in this embodiment, the metal soap 45c is supplied to the surface of the photoreceptor 1 to suppress the adhesion of the discharge products to the surface of the photoreceptor 1. FIG.

7. Metallic Soap Application Operation In Example 1, as described above, the developing roller 4 contacts the photosensitive member 1 to form a developing nip in the developing portion. Further, by providing a surface movement speed difference between the surface of the developing roller 4 and the surface of the photoreceptor 1 , the toner 10 rotates at the developing nip portion and the metal soap 45 c is supplied to the photoreceptor 1 . Hereinafter, the ratio of the surface moving speed of the developing roller 4 to the surface moving speed of the photoreceptor 1 is referred to as the DD peripheral speed ratio. When applying the metal soap 45c to the photoreceptor 1, image deletion tends to be improved as the DD peripheral speed ratio is increased. It can be considered that this is because the rolling of the toner 10 increases due to the increase in the DD peripheral speed ratio, and the chances of contact between the metal soap 45c and the photoreceptor 1 increase. Further, when the DD peripheral speed ratio is 100% or less, the contact area of the developing roller 4 per unit area of the photoreceptor 1 decreases. % is desirable. That is, it is desirable that the surface moving speed of the developing roller 4 is higher than the surface moving speed of the photoreceptor 1 . The DD peripheral speed ratio is an index that expresses the difference in surface moving speed between the surface of the photosensitive member 1 and the surface of the developing roller 4. For example, instead of the DD peripheral speed ratio, the surface moving speed difference (DD peripheral speed difference) may be used as an index.

However, if the image forming operation is always performed with the DD circumferential speed ratio being large, the metallic soap 45c will be excessively supplied in the initial stage, and the metallic soap 45c will be depleted from the developing chamber 3a and the toner containing portion 3b. . In addition, the number of times the toner 10 is rubbed increases, degrading the toner 10 and impairing the chargeability.

Therefore, in the first embodiment, the metallic soap application operation is prepared separately from the normal image forming operation. In addition, the DD peripheral speed ratio is made larger than the image forming operation. During the metal soap coating operation, a charging voltage is applied to control the photoreceptor 1 to be the dark potential Vd, and the developing voltage is set to the same as that during the image forming operation, thereby performing so-called solid white printing.

The timing for executing the metallic soap application operation is preferably during the rotation of the photoreceptor 1 before the image forming operation or during the rotation of the photoreceptor 1 after the image forming operation. That is, it is executed during a non-image forming operation in which an image forming operation is not performed. However, if the current can be detected with high accuracy, the current detection may be performed during the image forming operation. In this embodiment, the decision unit 156 decides whether or not the metal soap applying operation can be executed according to the value of the charging current that flows when the charging voltage is applied. In this embodiment, control is performed so that the metallic soap application operation is executed when the charging current value exceeds a predetermined threshold value.

During the metallic soap coating operation, it is desirable to make the back contrast Vback, which is the potential difference between the dark area potential Vd and the developing voltage, larger than that during normal image formation. Metallic soap 45c charged to a polarity opposite to that of toner 10 electrically adheres to the surface of photoreceptor 1 as Vback increases. This is because it can adhere to In this embodiment, Vback is set to 200 V during normal image formation, whereas it is set to 300 V during the metal soap coating operation. Specifically, the developing voltage is set from -300V to -200V. Alternatively, in order to set the dark potential Vd from -500V to -600V, -1100V, which is -100V added to the charging voltage, may be applied to the charging roller 2 .

Further, it is preferable that the amount of light of the pre-exposure unit 27 is made smaller during the metallic soap application operation than during the image forming operation, and it is particularly preferable to turn it off. This is because the smaller the amount of pre-exposure during the metallic soap coating operation, the better the image deletion. The following phenomenon can be considered as the cause of such a tendency. By reducing the amount of pre-exposure, the charge remaining on the surface of the photoreceptor 1 is not eliminated and residual charge remains. Therefore, the electrical adhesion of the positive metal soap 45c, which is opposite to the normal polarity, to the photoreceptor 1 is strengthened, so that the metal soap 45c is less likely to come off from the surface of the photoreceptor 1. FIG. In this state, when the metal soap 45c on the photoreceptor 1 passes through the cleaning blade 8 and the developing roller 4, the metal soap 45c is physically pushed into the photoreceptor 1 and strongly adheres to it. In other words, by setting the amount of pre-exposure to be smaller than that during the image forming operation, it is possible to increase the ability of the metal soap coating operation to hold the metal soap 45c on the photoreceptor 1, thereby firmly adhering the metal soap 45c to the photoreceptor 1. It is possible. On the other hand, if the amount of exposure of the surface of the photoreceptor 1 is increased, the electrical adhesion of the positive metal soap 45c to the photoreceptor 1 is weakened, and the surface of the photoreceptor 1 may be easily peeled off.

Further, it is desirable that the potential difference ΔVr (=Vdc−Vr) of the supply roller 5 with respect to the developing roller 4 is opposite in polarity to the polarity of the metal soap 45c. That is, the potential difference ΔVr is controlled so that the potential difference in the direction in which the electrostatic force acts on the metal soap 45c in the direction from the supply roller 5 toward the developing roller 4 is formed at the contact portion where the supply roller 5 and the developing roller 4 contact each other. It means that By setting ΔVr to have a polarity opposite to the polarity with which the metal soap 45c is charged, the metal soap 45c can be moved toward the developing roller 4 and can be suppressed from moving toward the supply roller 5. A large amount of metal soap 45c can be provided on the surface of body 1. In this embodiment, .DELTA.Vr=-50 V and the metal soap 45c is positively charged, so the metal soap 45c positively moves toward the developing roller 4 side.

8. Control Procedure of Metal Soap Application Operation Next, the timing of the metal soap application operation will be described.

In this embodiment, the charging current that flows through the charging roller 2 is detected by the charging current detector 36, and the metal soap application operation timing is determined based on the charging current value.

In order to detect the charging current flowing through the charging roller 2, this embodiment has a charging current detection section 36 as shown in FIG. The charging current detection unit 36 detects the charging current value while applying a DC voltage to the charging roller 2 by receiving a signal from the CPU 155 .

FIG. 6 shows the transition of the charging current value detected when the pre-exposure is OFF. From the beginning of printing to the middle of the number of printed sheets, the charging current value is stable even if paper is passed through. value increases. Further, if the endurance is continued as it is, the charging current value rises and image deletion occurs (thick dotted line in the figure). In this embodiment, a threshold value is set within a range in which image deletion does not occur with respect to an initial normal charging current value ("threshold value of charging current value" in the figure), and charging voltage application detected when pre-exposure is OFF. The timing of the metallic soap application operation is determined by comparing the current value of the charging current flowing from time to time with a predetermined threshold value. The metal soap application operation timing is determined by the above-described method, and the metal soap application operation is executed. In this embodiment, the threshold value of the charging current value is set to 25 μA. It was confirmed that when the current exceeds 25 μA, image deletion occurs slightly in the output image. When the charge transport layer of the photosensitive member 1 is 16 μm and the applied charging voltage is 1000 V, the initial charging current value is 20 μA. The threshold is preferably in the range of 25-32 μA. Δ between the initial current value and the threshold value is 2 to 5 μA, and this Δ indicates the amount of discharge product adhered to the surface of the photoreceptor 1 . The details of the threshold range and the range of Δ will be described later. This embodiment is characterized in that, in the metal soap application operation, the metal soap is applied to suppress the adhesion of discharge products until Δ becomes substantially zero.

This embodiment is characterized in that the metallic soap application operation is executed when the detected charging current value exceeds a predetermined threshold value, but the condition for executing the metallic soap application operation is not limited to this. For example, it may be executed when the value of Δ exceeds a predetermined value. That is, when the charging current value of the charging current detected by the charging current detection unit 36 is the first current value, the coating operation is not executed and the second current having a larger absolute value than the first current value is detected. In the case of a value, a coating operation may be executed. Here, .DELTA. can be appropriately set, and when .DELTA. increases even a little, by executing the metallic soap application operation, there is an effect that the discharge products generated on the surface of the photoreceptor 1 can be removed. .

Next, with reference to the flow chart of FIG. 7, the control procedure of the metallic soap application operation for avoiding image deletion will be described. In Example 1, the control unit 202 executes the metallic soap application operation.

The process cartridge 7 has a memory 15, and the memory 15 stores the initial charging current value and the threshold value of the charging current value described above. When a print signal is input (S1), an image forming operation is executed (S2). When the image forming operation ends (S3), the CPU 155 provided in the image forming apparatus 100 communicates with the memory 15 and reads the initial charging current value and the charging current value threshold (S4).

Next, the CPU 155 detects the charging current by the current detection unit 36 and measures the current charging current value at the desired charging voltage (S5). Then, by comparing the current charging current value with the set threshold value of the charging current value, it is determined whether or not it is time to execute the metallic soap application operation (S6).

When the current charging current value exceeds the set threshold value, it is time to execute the metallic soap application operation, and the metallic soap application operation is started (S7).

First, a charging voltage, a developing voltage, a blade voltage, and a toner supply voltage are applied, and the driving of the developing roller 4 and the photoreceptor 1 is started to bring the developing roller 4 into contact with the photoreceptor 1 (S8).

Next, while detecting the charging current, the metal soap application operation is continued until the initial charging current value is reached (S9).

When the initial charging current value is reached, the developing roller 4 is separated from the photoreceptor 1, the driving of the developing roller 4 and the photoreceptor 1 is stopped, the applied voltage is turned off (S10), and the metal soap is applied. (S11).

When the metal soap applying operation is completed, it is determined whether or not there is a request for continuous printing (S12). If there is no request, the operation proceeds to the end of printing (S13). , S2 to S12 are repeated.

Incidentally, the metallic soap applying operation in S8 may be executed in a state in which the application of various voltages and driving are performed as they are after the image forming operation in S3 without performing the separation operation of the developing roller 4. FIG.

Further, as shown in the flowchart shown in FIG. 8, current detection may be performed before the image forming operation is performed, and the metallic soap application operation may be performed. The flowchart of FIG. 8 will be described.

When a print signal is input (S21), the CPU 155 provided in the image forming apparatus 100 communicates with the memory 15 and reads the initial charging current value and the charging current value threshold (S22).

Next, the CPU 155 detects the charging current by the charging current detector 36 and measures the current charging current value at the desired charging voltage (S23). Then, by comparing the current charging current value with the set threshold value of the charging current value, it is determined whether or not it is time to execute the metallic soap application operation (S24).

When the current charging current value exceeds the set threshold value, it is time to execute the metallic soap application operation, and the metallic soap application operation is started (S25).

First, a charging voltage, a developing voltage, a blade voltage, and a toner supply voltage are applied, and the driving of the developing roller 4 and the photoreceptor 1 is started to bring the developing roller 4 into contact with the photoreceptor 1 (S26).

Next, while detecting the charging current, the metallic soap application operation is continued until the initial charging current value is reached (S27).

When the initial charging current value is reached, the developing roller 4 is separated from the photoreceptor 1, the driving of the developing roller 4 and the photoreceptor 1 is stopped, the applied voltage is turned off (S28), and the metal soap is applied. is terminated (S29), and the image forming operation is started (S30).

When the image forming operation is finished, it is determined whether or not there is a request for continuous printing (S31). The operations of S23 to S31 are repeated.

The metallic soap application operation is performed until Δ becomes 0, and the metallic soap application operation time is preferably between 2 seconds and 30 seconds. At least, it is necessary to carry out for a time longer than one rotation of the photoreceptor 1 . Since downtime occurs even if the metallic soap application operation time is too long, it is preferable to set it appropriately. While the charging current detection unit 36 performs current detection while the metallic soap application operation is being performed, the detected charging current value may be checked, and when Δ becomes 0, the metallic soap application operation may be terminated. .

9. Effect of Metallic Soap Applying Operation The effect of performing the metallic soap applying operation described in this embodiment was confirmed. Table 2 shows the DD peripheral speed ratio and voltage settings for the metal soap application operation in Comparative Example 1, Comparative Example 2, and Example 1. Table 3 shows the metallic soap application operation and whether or not the charging current detection performed when executing the metallic soap application operation is executed.

As shown in Tables 2 and 3, Comparative Example 1 does not perform the metal soap application operation described in Example 1. In Comparative Example 2, the metallic soap application operation was performed for 5 seconds every predetermined number of sheets (100 sheets in this embodiment) without detecting the charging current. On the other hand, in Example 1, as a result of detecting the charging current, when the current value exceeded the threshold value, the metallic soap application operation was performed, and the metallic soap application operation was continued until the initial charging current value was reached.

The results of the actual effect confirmation are shown below. In order to confirm the occurrence of image smearing in Example 1, Comparative Example 1, and Comparative Example 2, 10,000 sheets of paper were continuously fed per day at a printing rate of 1%, and left in the machine for one day. compared. The reason why the evaluation is made after being left for one day is that the discharge products generated on the surface of the photoreceptor 1 absorb moisture sufficiently by being left for one day, and the effect of lowering the surface resistance of the photoreceptor 1 becomes noticeable. is. A halftone image was printed on one sheet and evaluated as a sample for judging the presence or absence of image smearing. The evaluation index is as follows.

〇: Not generated No white spots due to latent image dulling or outline blurring at image boundaries across the entire image ×: Occurrence The output environment was 30° C./80% RH. The total number of sheets passed was up to 120,000 sheets. Table 4 shows the results.

As shown in Table 4, in Comparative Example 1, although the image quality was good up to 20,000 sheets, image deletion occurred after 40,000 sheets. Initially, the image flow is good because the metal soap 45c is supplied together with the toner 10, but as the image formation is repeated, the amount of the metal soap 45c remaining on the surface of the photoreceptor 1 becomes larger than the amount of the metal soap 45c that can be supplied. less. Therefore, it is considered that the image deletion occurred because the metal soap 45c could not be supplied in time only by the image forming operation.

In Comparative Example 2, the life was extended by 60,000 sheets compared to Comparative Example 1, but image deletion occurred after 100,000 sheets. The life was extended compared to Comparative Example 1 by the amount of the metal soap application operation. It is considered that this is because the metal soap 45c is positively supplied to the photoreceptor 1 in the metal soap application operation, and the effect of suppressing the image deletion is exhibited. However, since the metallic soap application operation was performed uniformly at the same timing from the beginning, the required amount of metallic soap 45c could not be supplied onto the surface of photoreceptor 1 at the final stage when metallic soap 45c was exhausted. It is thought that this is because The metal soap 45c that was excessively supplied at the beginning was scraped off by the cleaning blade 8, and the effect could not be maintained as in the second comparative example. Furthermore, there was a problem that the throughput was lowered due to the periodical execution of the metallic soap coating operation.

On the other hand, in Example 1, the image deletion was good even after reaching 120,000 sheets. It is considered that this is because, in addition to the effects of the metallic soap application operation, the charging current detection was performed, and an appropriate amount of metallic soap 45c adhered to the photoreceptor 1 at an appropriate timing.

The toner 10 to which the metallic soap 45c is externally added is effective for image smearing, but as the image formation is repeated, the metallic soap 45c that can be supplied becomes insufficient, and if the current detection is not performed, the image smearing should be sufficiently suppressed. I couldn't do it. However, in the configuration of this embodiment, the image deletion can be suppressed by adding the metallic soap 45c to the toner 10 and performing the following control. The image forming apparatus 100 of this embodiment includes a current detection section 36 for detecting a current flowing from the charging roller 2 to the photoreceptor 1 while a charging voltage is applied to the charging voltage applying section 71, which is the first voltage applying section. , and a control unit 202 for controlling the charging voltage application unit 71 . The toner 10 contains the metal soap 45c, and performs an image forming operation for forming a toner image on the recording material S and an application operation for applying the metal soap 45c to the surface of the photoreceptor 1. FIG. The control unit 202 controls to execute the metallic soap application operation based on the current value of the current flowing from the charging roller 2 to the photoreceptor 1 detected by the current detection unit 36 . When the current value of the current flowing from the charging roller 2 to the photoreceptor 1 detected by the current detection unit 36 exceeds a predetermined threshold value, the metallic soap applying operation is executed. Further, in the metallic soap coating operation, the speed ratio between the surface moving speed of the photoreceptor 1 and the surface moving speed of the developing roller 4 is controlled so as to be greater than the speed ratio in the image forming operation. Furthermore, the back contrast Vback, which is the difference between the surface potential of the surface of the photosensitive member 1 charged by the charging roller 2 in the developing section and the developing voltage applied to the developing roller 4, is higher in the metallic soap application operation. Make it larger than the forming action. As a result, even when the metal soap 45c is insufficient, the supply of the metal soap 45c to the photoreceptor 1 can be supplemented, and image deletion can be suppressed for a long period of time.

In general, when the abrasion of the photoreceptor is suppressed, the surface of the photoreceptor becomes difficult to refresh, resulting in image defects due to image smearing in a high-humidity environment. The toner to which the metal soap 45c is externally added is effective for image smearing, but as the image formation is repeated, the supply of the metal soap 45c becomes insufficient and the image smearing cannot be suppressed. However, in the configuration of this embodiment, it is possible to replenish the metal soap 45c to the photoreceptor 1 at an appropriate timing by detecting the current, thereby suppressing image deletion.

In this embodiment, the charging current is detected when the pre-exposure is OFF and the metallic soap application operation is performed. may be detected, and the metallic soap applying operation may be performed with the pre-exposure ON according to the detection result.

In this embodiment, the charging current detector 36 is connected to the charging roller 2 to detect the current flowing when the charging voltage is applied. can be detected by

In the configuration of the image forming apparatus 100 applied in this embodiment, the same reference numerals are given to the same members as in the first embodiment, and the description thereof will be omitted.

Embodiment 2 is characterized in that the metal soap application operation is executed at appropriate timing even when the film thickness of the photoreceptor 1 is reduced by repeating image formation and the dark potential (Vd) is increased. Since Vd increases as image formation is repeated, in this embodiment, the developing voltage, developing blade voltage, and toner supply voltage are appropriately changed in accordance with the increase in Vd. The abrasion rate of the photosensitive member 1 used in Example 2 was 0.048 to 0.050 (μm/1000 sheets). Therefore, the threshold value is appropriately changed in consideration of abrasion of the surface of the photoreceptor 1 . Specifically, the film thickness of the photoreceptor 1 at the initial stage is 16 μm, and the film thickness of the photoreceptor 1 after printing 120,000 sheets is approximately 10 μm. If the film thickness is less than 10 μm, the resistance of the surface of the photoreceptor 1 is lowered, which may cause image defects. In this example, the threshold value of the charging current value was set to 32 μA when the charge transport layer of the photoreceptor 1 had a thickness of 10 μm. When the charge transport layer of the photosensitive member 1 has a thickness of 10 μm, when the applied charging voltage is 1000 V, the charging current value is 30 μA, and Δ between the current value and the threshold value is 2 μA. As the film thickness of the photosensitive member 1 becomes thinner and the charging current value increases, the amount of discharge products generated increases, so Δ is set to be small. Since the charging current value changes according to the number of images formed, the threshold value is set so that Δ gradually decreases.

1. Execution Timing of Metal Soap Application Operation First, the metal soap application operation timing in this embodiment will be described.

In the second embodiment, as shown in FIG. 9, an information detection unit 16 for detecting usage information of the photoreceptor 1 and the charging roller 2 is provided. The information is used to set a threshold for the charging current value. Then, by comparing with the charging current value flowing through the charging roller 2, the metal soap application operation timing is determined.

FIG. 10 is a graph showing the relationship between the film thickness of the photosensitive member 1 and the charging current in an environment of 30° C./80% RH (H/H). The charging voltage is the voltage at which the initial dark potential is Vd=-500V. From this graph, it can be seen that the charging current linearly increases as the film thickness of the photoreceptor 1 becomes thinner. Point A in FIG. 10 is the threshold value of the initial charging current value. When the film thickness of the photoreceptor 1 becomes thin, the threshold value of the charging current value can be set by forming a straight line passing through the point A and parallel to the straight line.

Therefore, based on the measurement data, a calculation formula for calculating the assumed current charging current value corresponding to the film thickness change and the threshold value of the charging current value is obtained, and the data is stored in the ROM 33 of the main body of the image forming apparatus 100 in advance. . The assumed current charging current value and the threshold value of the charging current value can be calculated by employing the information on the film thickness of the photoreceptor 1 stored in the memory 15 and the approximate formula data stored in the ROM 33. I can.

Information about the film thickness of the photoreceptor 1 will be described in detail below.

Information about the film thickness of the photoreceptor 1 is calculated by the following method. As described above, the film thickness of the photoreceptor 1 deteriorates due to electric discharge, and the surface of the photoreceptor 1 is affected by the passage of the recording material S (passage of paper) or rubbing due to the contact of the cleaning blade 8. is scraped off.

In the image forming apparatus 100 of this embodiment, the decrease in the film thickness of the photoreceptor 1 is correlated with the charging voltage application time. In addition, this charging voltage application time is proportional to the number of images formed. Therefore, the reduction rate of the film thickness of the photoreceptor 1 in the photoreceptor 1 can be expressed as a linear function of the number of images formed. There is also a correlation between the number of images formed (P) and the number of rotations of the photosensitive member 1 (surface movement distance). Further, there is a correlation between the number of images formed (P) and the number of recording materials S used for printing. Therefore, the information about the film thickness of the photoreceptor 1 includes the number of images formed (P), the number of sheets of the recording material S passing through the image forming apparatus 100, the number of rotations of the photoreceptor 1, and the voltage applied by the voltage applying unit 71, which will be described later. It may be calculated using at least one of the application times.

In this embodiment, the memory 15 mounted in the process cartridge 7 stores the number of images (P) formed as information on the film thickness of the photoreceptor 1 . Then, using this information, the threshold value of the charging current value is calculated by the method described above, and is compared with the charging current value flowing through the charging roller 2 to determine the execution timing of the metallic soap application operation.

2. Control Procedure for Metallic Soap Application Operation Next, the control procedure for the metallic soap application operation for suppressing the occurrence of image deletion in this embodiment will be described with reference to the flowchart of FIG. In Example 2, the control unit 202 executes the metallic soap application operation.

The process cartridge 7 has a memory 15 in which the number of sheets (P) for image formation is stored. When a print signal is input (S41), the CPU 155 provided in the image forming apparatus main body 100 communicates with the memory 15, reads the number of images to be formed (P) (S42), and executes the image forming operation (S43). . When the image forming operation ends (S44), the count of the number of images formed is incremented by 1 (S45), and the count of the number of images formed in the memory 15 of the process cartridge 7 is rewritten (S46).

Next, the assumed charging current value corresponding to the number of images formed and the threshold value of the charging current value are compared with the value (P) of the number of images formed read into the CPU 155, and the assumed current charging current value and the threshold value of the charging current value are compared. A threshold value of the charging current value is determined (S47).

The charging current is detected to measure the current charging current value at the desired charging voltage (S48), and the measured charging current value is compared with the determined charging current threshold value to determine whether the metal soap is applied. It is determined whether or not it is time to operate (S49).

When the measured charging current value exceeds the determined threshold value, it is time to execute the metallic soap application operation, and the metallic soap application operation is started (S50).

First, a charging voltage, a developing voltage, a developing blade voltage, and a supply voltage are applied, and the driving of the developing roller 4 and the photoreceptor 1 is started to bring the developing roller 4 into contact with the photoreceptor 1 (S51).

Next, while detecting the charging current, the metallic soap application operation is continued until the assumed current charging current value is reached (S52).

When the assumed current charging current value is reached, the developing roller 4 is separated from the photoreceptor 1, the driving of the developing roller 4 and the photoreceptor 1 is stopped, the applied voltage is turned off (S53), and the metal The soap application operation is terminated (S54).

When the metallic soap application operation is finished, it is then determined whether or not there is a request for continuous printing (S55). If there is no request, the process shifts to the print end operation (S56).

In the configuration of the second embodiment, even when the dark potential (Vd) rises due to the decrease in the film thickness of the photoreceptor 1, the metallic soap application operation can be executed at appropriate timing. As a result, it is possible to stably maintain the metallic soap 45c on the surface of the photoreceptor 1 regardless of the film thickness. Therefore, it is possible to suppress the occurrence of image smearing.

In Examples 1 and 2, the charging voltage was constant from the beginning to the end of image formation. The third embodiment is characterized in that the charging voltage is changed according to the usage and usage environment of the image forming apparatus 100 so that the dark potential (Vd) is always substantially constant. The image forming apparatus 100 of Example 3 further includes an environment detection unit 17 as shown in FIG. The environment detection unit 17 detects one or both of temperature and relative humidity. When detecting both, the absolute humidity may be calculated from the detection results.

In this embodiment, the configuration in which the environment detection unit 17 is provided in the cartridge 7 is adopted, but the configuration in which the environment detection unit 17 is provided in the image forming apparatus 100 is also possible.

1. Timing of Metallic Soap Application Operation Timing of the metal soap application operation in this embodiment will be described.

In the third embodiment, information about the film thickness of the photoreceptor 1, information about the usage environment, and information about the charging voltage, that is, the charging performance and the environment are used to set the threshold value of the charging current value, and the charging current value flowing to the charging roller 2 is set. to determine the timing of the metallic soap application operation. Information about the charging ability of the charging roller 2 is calculated using information about the charging voltage and the film thickness of the photoreceptor 1 .

FIG. 13 shows the results in a 30° C./80% RH environment (H/H), a 23° C./50% RH environment (N/N), and a 15° C./10% RH environment (L/L) when new. It is a graph showing the relationship between charging voltage and charging current. From this graph, it can be seen that the charging current increases linearly as the charging voltage increases. Also, it can be seen that the higher the temperature and humidity, the more the charging current increases even with the same charging voltage. Point B is the threshold value of the charging current value in the initial environment of 30° C./80% RH. When the charging voltage changes, the threshold value of the charging current value can be set by forming a straight line passing through the point B and parallel to the straight line. That is, the threshold is set higher as the charging voltage rises. The relationship between the film thickness of the photosensitive member 1 and the charging current is as described in the second embodiment.

Based on these measurement data (the relationship between the film thickness of the photoreceptor 1 and the charging current, the relationship between the usage environment and the charging current, and the relationship between the charging voltage and the charging current), the assumed current charging current value and a formula for calculating the threshold value of the charging current value. Then, the data is stored in the ROM 33 of the image forming apparatus 100 in advance. The assumed current charging current value and charging current threshold value are approximate expressions stored in the ROM 33 corresponding to the information about the film thickness of the photoreceptor 1, the information about the usage environment, and the information about the charging voltage stored in the memory 15. It can be calculated by adopting the above data. As a method for obtaining an approximation formula, there are statistical methods such as linear approximation, exponential approximation, polynomial approximation, cumulative approximation, and moving average approximation.

Information on the usage environment is calculated by the following method. The image forming apparatus 100 has an environment sensor as the environment detection unit 17 , detects the temperature T and the relative humidity H at predetermined time intervals, and rewrites the information about the usage environment in the memory 15 .

In the third embodiment, the memory 15 mounted on the process cartridge 7 stores the number of images formed (P) as information about the film thickness of the photosensitive member 1, the temperature T and the relative humidity H as information about the usage environment, and the charging voltage as information about the charging voltage. Store the voltage setting value. Then, using these three pieces of information, the threshold value of the charging current value is calculated by the method described above, and is compared with the charging current value flowing through the charging roller 2 to determine the metal soap applying operation timing.

2. Control Procedure of Metal Soap Application Operation Next, a control procedure of the metal soap application operation for suppressing the occurrence of image deletion will be described with reference to the flowchart of FIG. 14 . In Example 3, the control unit 202 executes the metallic soap application operation.

The process cartridge 7 has a memory 15, and the memory 15 stores the number of image formation sheets (P), the temperature T, the humidity H, and the charging voltage setting value. When a print signal is input (S61), the CPU 155 provided in the image forming apparatus main body 100 communicates with the memory 15 to read the number of images to be formed (P), the temperature T, the relative humidity H, and the charging voltage set value ( S62), and an image forming operation is executed (S63). When the image forming operation ends (S64), the count of the number of images formed is incremented by 1 (S65), and the count of the number of images formed in the memory 15 of the process cartridge 7 is rewritten (S66).

Next, the contents of the ROM 33 on the side of the image forming apparatus 100, in which the assumed charging current value and the threshold value of the charging current value are stored in advance, are compared with the number of images to be formed P, the temperature T, the relative humidity H, and the charging voltage set value. Then, the charging current value and the threshold value of the charging current value are determined (S67).

The charging current is detected, the current charging current value at the desired charging voltage is measured (S68), and the measured charging current value is compared with the determined threshold value of the charging current value to execute the metallic soap application operation. It is determined whether or not it is time to do so (S69).

When the measured charging current value exceeds the determined threshold value, it is time to execute the metallic soap application operation, and the metallic soap application operation is started (S70).

First, a charging voltage, a developing voltage, a developing blade voltage, and a supply voltage are applied, and the driving of the developing roller 4 and the photoreceptor 1 is started to bring the developing roller 4 into contact with the photoreceptor 1 (S71).

Next, while detecting the charging current, the metallic soap application operation is continued until the assumed current charging current value is reached (S72).

When the assumed current charging current value is reached, the developing roller 4 is separated from the photoreceptor 1, the driving of the developing roller 4 and the photoreceptor 1 is stopped, the applied voltage is turned off (S73), and the metal The soap application operation is terminated (S74).

Subsequently, it is determined whether there is a request for continuous printing (S75), and the operations of S63 to S75 are repeated until there is no request for continuous printing. If there is no request, the process shifts to the print end operation (S76).

In the configuration of the third embodiment, even when the charging voltage is changed according to the usage history and usage environment of the image forming apparatus, the metal soap is applied at appropriate timing so that the dark potential (Vd) is always substantially constant. can perform actions. As a result, the metal soap 45c can be stably maintained on the surface of the photoreceptor 1, and the durability of the photoreceptor 1 can be maintained even in a configuration with a longer service life. It is possible to suppress the occurrence.

In Example 3, the image forming operation was performed in the H/H environment of 30° C./80% RH, but even if the environment changes, the threshold value of the charging current value can be appropriately set by performing the above control. Therefore, the metallic soap application operation can be executed at appropriate timing.

Due to the exposure process in the image forming operation, residual charges are generated in the photosensitive layer of the photoreceptor 1, and the light area potential Vl may fluctuate during image formation. Therefore, the present embodiment is characterized in that charging current detection is performed while suppressing an increase in Vl (referred to as Vl-up) caused by the influence of residual charges.

1. Undercoat Layer of Photoreceptor The photoreceptor b of this example and the photoreceptor c of Comparative Example 3 differ from the photoreceptor a used in Examples 1 to 3 in the undercoat layer. The undercoat layers of photoreceptor b and photoreceptor c were prepared by the following method.

First, a method for forming the undercoat layer of the photoreceptor b of this embodiment will be described. 100 parts of rutile-type titanium oxide particles (average primary particle diameter: 50 nm, manufactured by Tayka) were stirred and mixed with 500 parts of toluene, and 5.0 parts of vinyltrimethoxysilane (trade name: KBM-1003, manufactured by Shin-Etsu Chemical) was added. , and stirred for 8 hours. After that, toluene was distilled off under reduced pressure and dried at 120° C. for 3 hours to obtain rutile-type titanium oxide particles surface-treated with vinyltrimethoxysilane. 18 parts of rutile-type titanium oxide particles surface-treated with vinyltrimethoxysilane, 4.5 parts of N-methoxymethylated nylon (trade name: Toresyn EF-30T, manufactured by Nagase ChemteX), copolymerized nylon resin (trade name: Amilan CM8000 (manufactured by Toray) (1.5 parts) was added to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol to prepare a dispersion. This dispersion liquid was subjected to dispersion treatment for 5 hours in a vertical sand mill using glass beads having a diameter of 1.0 mm to prepare a coating liquid for an undercoat layer. This undercoat layer coating liquid was applied onto the support by dip coating, and the resulting coating film was dried at 100° C. for 10 minutes to form an undercoat layer having a thickness of 2.0 μm.

Next, a method for forming the undercoat layer of the photoreceptor c of Comparative Example 3 will be described. A coating solution for an undercoat layer was prepared by dissolving 40 parts of a copolymerized nylon resin (trade name: Amilan CM4000, manufactured by Toray) in a mixed solvent of 450 parts of methanol/150 parts of n-butanol. This undercoat layer coating liquid was applied onto the conductive layer by dip coating, and the resulting coating film was dried to form an undercoat layer having a thickness of 0.8 μm.

2. Vl-up Next, the phenomenon caused by Vl-up will be described. FIG. 15(a) shows Vl increase amount when image formation is continuously performed in an environment (L/L) of 15° C./10% RH, and FIG. 15(b) shows an environment of 30° C./80% RH. (H/H) indicates the Vl increase amount when image formation is continuously performed. As shown in FIGS. 15(a) and 15(b), Vl-up occurs with image formation. As shown in FIG. 15(a), it is confirmed that the rate of increase of Vl per unit time increases as the absolute humidity decreases, and Vl increases to V1. On the other hand, as shown in FIG. 15(b), in an environment where the absolute humidity is high, the rate of increase in Vl is small, Vl does not rise so much, and Vl rises only to V2 whose absolute value is smaller than V1. It is considered that the Vl increase is mainly caused by an increase in the number of residual charges in the photosensitive layer due to exposure of the photosensitive member 1 during image formation. In other words, in an environment with low absolute humidity, the cause of the Vl increase was thought to be that the resistance of one of the photosensitive layers increased, making it difficult for charges to move or be injected smoothly. Thus, in an environment with low absolute humidity, Vl-up occurs due to the accumulation of residual charges in the high-resistance layer during image formation.

Here, when Vl-up occurs, the development contrast Vcont, which is the difference between the development voltage Vdc and Vl, fluctuates due to the exposure process of the photoreceptor 1 accompanying image formation. This leads to a change in the toner bearing amount on the photoreceptor 1 and causes a change in image density on the recording material S. FIG.

From the above, it is considered that the magnitude of the Vl increase changes depending on the resistance and prescription of the undercoat layer. Furthermore, it is presumed that the resistance of the undercoat layer gradually increases when it is exposed to light for image formation, and the Vl increase becomes conspicuous because the charge does not move smoothly. Therefore, the degree of Vl increase was changed by changing the resistance and prescription of the undercoat layer, and the influence of Vl increase was confirmed. The photoreceptor a used in Examples 1 to 3, the photoreceptor b used in Example 4, and the photoreceptor c used in Comparative Example 3 were compared in terms of Vl increase amount when images were formed on 100,000 sheets. As a result, while the photoreceptor a and the photoreceptor b hardly increased in Vl, the photoreceptor c increased in Vl by 50V.

3. Confirmation of Effect The results of confirming the effect of the metallic soap application operation in detecting the charging current in this embodiment are shown below. In order to confirm the occurrence of smeared images in Examples 1, 4 and Comparative Example 3, 10,000 sheets of paper were continuously fed per day at a printing rate of 1%, and left in the machine for a day. compared with and without. The reason why the evaluation is made after being left for one day is that the discharge products generated on the surface of the photoreceptor 1 absorb moisture sufficiently by being left for one day, and the effect of lowering the surface resistance of the photoreceptor 1 becomes noticeable. is. A halftone image was printed on one sheet and evaluated as a sample for judging the presence or absence of image smearing. The evaluation index is as follows.
〇: Not generated No white spots due to latent image dulling or outline blurring at image boundaries across the entire image ×: Occurrence

The environment for paper feeding and sample output was 30° C./80% RH. The total number of sheets passed was up to 120,000 sheets. Table 5 shows the results.

As shown in Table 5, in Examples 1 and 4 in which Vl-up did not occur, image deletion did not occur even after printing 120,000 sheets. On the other hand, in Comparative Example 3, although the image quality was good up to 80,000 sheets, image deletion occurred after 100,000 sheets. Until the middle stage of the endurance, the residual amount of toner was large and the metallic soap 45c was sufficiently supplied, so the image deletion was good. However, as the image formation was repeated, the amount of toner decreased, and the metal soap 45c that could be supplied was exhausted, resulting in image deletion. In Comparative Example 3, the undercoat layer was different from those in Examples 1 and 4, and the carrier transport ability decreased due to deterioration during repeated image formation. Negative charges were accumulated in the undercoat layer, and the bright area potential Vl increased. Since the charging current value decreased as the light area potential Vl increased, the threshold value of the charging current was not exceeded, and the metallic soap application operation was not executed, resulting in image deletion.

In the configuration of the fourth embodiment, by using the photoreceptor 1 in which the bright area potential Vl does not increase even if image formation is repeated, the metal soap application operation can be executed at appropriate timing. As a result, the metal soap 45c can be stably maintained on the surface of the photoreceptor 1. By suppressing the change in Vl, the durability of the photoreceptor can be maintained even in a long-life configuration, and a simple structure can be obtained. The configuration makes it possible to suppress the occurrence of image smearing.

In Example 4, the value of Vl also changes when the surface of the photoreceptor 1 is scraped. In that case, the control may be performed by applying the content described in the second embodiment.

In Example 5, as in Example 4, the case where the light area potential (Vl) increases by repeating image formation will be described. The difference from Example 4 is that Example 4 uses an undercoat layer that is less susceptible to Vl-up, whereas Example 5 uses the photoreceptor c of Comparative Example 3 that causes Vl-up. This embodiment is characterized in that the charging current is detected while considering the Vl increase caused by the influence of the residual charge.

1. Control Procedure of Metal Soap Application Operation First, the timing of the metal soap application operation in the fifth embodiment will be described. In Example 5, the threshold value of the charging current value is set using the information on the image exposure and the pre-exposure, and the charging current value flowing through the charging roller 2 is compared with the charging current value to determine the metal soap applying operation timing.

FIG. 16 is a graph showing the relationship between the irradiation time of imagewise exposure and pre-exposure in an environment of 30° C./80% RH and the charging current. From this graph, it can be seen that the charging current decreases linearly with increasing irradiation time for image exposure and pre-exposure. The reason for this will be explained. Negative charges accumulate in the undercoat layer as image formation is repeated. Therefore, when image formation was repeated, the bright area potential Vl increased and the charging current decreased. Point C is the threshold value of the charging current value in the initial environment of 30° C./80% RH. Point C is the threshold value of the charging current value in the initial environment of 30° C./80% RH. By forming a straight line passing through the point C and parallel to the straight line, the threshold value of the charging current value can be set according to the irradiation time of the image exposure and the pre-exposure.

Therefore, based on this measurement data (the relationship between the irradiation time of image exposure and pre-exposure and the charging current), a calculation formula for calculating the assumed current charging current value and the threshold value of the charging current value is obtained, and the data are stored in the ROM 33 of the image forming apparatus 100 in advance. The assumed current charging current value and the charging current value threshold value are calculated by adopting the approximate formula data stored in the ROM 33 corresponding to the information on the image exposure and pre-exposure stored in the memory 15. can be done.

In the fifth embodiment, the memory 15 mounted on the process cartridge 7 stores the irradiation time as information on image exposure and pre-exposure. Then, using this information, the threshold value of the charging current value is calculated by the above-described method, and is compared with the charging current value flowing through the charging roller 2 to determine the metallic soap applying operation timing.

2. Control Procedure for Metal Soap Application Operation Next, a control procedure for the metal soap application operation for suppressing the occurrence of image deletion will be described with reference to the flowchart of FIG. 17 . In Example 5, the control unit 202 executes the metallic soap application operation.

The process cartridge 7 has a memory 15, and the memory 15 stores the irradiation times for image exposure and pre-exposure. When a print signal is input (S81), the CPU 155 provided in the image forming apparatus 100 communicates with the memory 15, reads the irradiation times for image exposure and pre-exposure (S82), and executes the image forming operation (S83). ). When the image forming operation is completed (S84), the irradiation times for image exposure and pre-exposure are integrated (S85), and the irradiation times for image exposure and pre-exposure in the memory 15 of the process cartridge 7 are rewritten (S86).

Next, the threshold values of the charging current value and the charging current value corresponding to the irradiation times of the image exposure and pre-exposure are compared with the irradiation times of the image exposure and pre-exposure read in the CPU 155 as described above, and the assumed current situation is determined. and the threshold value of the charging current value are determined (S87).

The charging current is detected, the current charging current value at the desired charging voltage is measured (S88), and the measured charging current value is compared with the determined charging current threshold value to execute the metallic soap application operation. It is determined whether or not it is time to do so (S89).

When the measured charging current value exceeds the determined threshold value, it is time to execute the metallic soap application operation, and the metallic soap application operation is started (S90).

First, a charging voltage, a developing voltage, a developing blade voltage, and a supply voltage are applied, and the driving of the developing roller 4 and the photoreceptor 1 is started to bring the developing roller 4 into contact with the photoreceptor 1 (S91).

Next, while detecting the charging current, the metallic soap application operation is continued until the assumed current charging current value is reached (S92).

When the assumed current charging current value is reached, the developing roller 4 is separated from the photoreceptor 1, the driving of the developing roller 4 and the photoreceptor 1 is stopped, the applied voltage is turned off (S93), and the metal The soap applying operation is ended (S94).

When the metal soap application operation is completed, it is then determined whether there is a request for continuous printing (S95), and the operations of S83 to S95 are repeated until there is no request for continuous printing. If there is no request, the process shifts to the print end operation (S96).

3. Confirmation of effects The results of actual confirmation of effects are shown below. In order to confirm the occurrence of smeared images in Example 5 and Comparative Example 3, 10,000 sheets of paper were continuously fed per day at a printing rate of 1%, and left in the machine for one day to compare the presence or absence of smeared images after standing. The reason why the evaluation is made after being left for one day is that the discharge products generated on the surface of the photoreceptor 1 absorb moisture sufficiently by being left for one day, and the effect of lowering the surface resistance of the photoreceptor 1 becomes noticeable. is. A halftone image was printed on one sheet and evaluated as a sample for judging the presence or absence of image smearing. The evaluation index is as follows.
〇: Not generated No white spots due to latent image dulling or outline blurring at image boundaries across the entire image ×: Occurrence

The environment for paper feeding and sample output was 30° C./80% RH. The total number of sheets passed was up to 120,000 sheets. Table 6 shows the results.

As shown in Table 6, in Example 5, image deletion did not occur even after printing 120,000 sheets. On the other hand, in Comparative Example 3, although the image quality was good up to 80,000 sheets, image deletion occurred after 100,000 sheets. In both cases, image deletion was good until the middle stage of the endurance test because the remaining amount of toner was large and the metallic soap 45c was sufficiently supplied. In both Example 5 and Comparative Example 3, the undercoat layer having the same formulation is used. In both cases, it was confirmed that Vl-up occurred by repeating image formation.

However, in Comparative Example 3, as image formation was repeated, the amount of toner decreased, and the metal soap 45c that could be supplied was depleted, resulting in image deletion. This is thought to be because the effect of the increase in the light area potential Vl due to the decrease in the carrier transport ability due to deterioration due to deterioration and the accumulation of negative charges in the undercoat layer during repeated image formation was not taken into account. be done. In Comparative Example 3, the execution condition of the metallic soap application operation was set without considering the influence of the decrease in the charging current value accompanying the increase in the bright area potential Vl. metal soap application operation is not executed. Therefore, Vl-up occurred, and image deletion occurred near 100,000 sheets when the toner amount decreased.

On the other hand, in the configuration of Example 5, even when the light area potential Vl rises by repeating image formation, the metallic soap application operation can be executed at an appropriate timing. In the fifth embodiment, the memory 15 mounted on the process cartridge 7 stores the irradiation time as information on image exposure and pre-exposure. Then, using this information, the threshold value of the charging current value is calculated by the above-described method, and is compared with the charging current value flowing through the charging roller 2 to determine the metallic soap applying operation timing. As a result, the metal soap 45c can be stably maintained on the surface of the photoreceptor 1 even if the photoreceptor 1 causing Vl-up is used. Therefore, it is possible to suppress the occurrence of image deletion while maintaining the durability of the photoreceptor 1 even in a more inexpensive configuration.

In this embodiment, the irradiation time is stored as the information on image exposure and pre-exposure. At least one of them may be used for calculation.

In Example 6, by forming a protective layer on the surface of the photoreceptor 1, the durability of the photoreceptor is maintained even in a configuration with a longer life, and the occurrence of image deletion is suppressed with a simple configuration. characterized by being

1. Protective Layer of Photoreceptor The photoreceptor 1 may have a protective layer on the photosensitive layer. When the photoreceptor 1 has a protective layer, the protective layer is the surface layer. The photoreceptor 1 in this embodiment is provided with an abrasion-resistant protective layer as the outermost layer in order to improve abrasion resistance. Durability can be improved by providing a protective layer. The protective layer as a surface layer has a universal hardness value (HU) of 210 or more and 250 or less (N/mm ² ) and an elastic deformation rate (We) of 37% or more and 52% or less.

The protective layer preferably contains conductive particles and/or a charge transport material and a resin. Conductive particles include particles of metal oxides such as titanium oxide, zinc oxide, tin oxide, and indium oxide. Charge-transporting substances include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred.

Examples of resins include polyester resins, acrylic resins, phenoxy resins, polycarbonate resins, polystyrene resins, phenol resins, melamine resins, and epoxy resins. Among them, polycarbonate resins, polyester resins, and acrylic resins are preferred.

The protective layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. The reaction at that time includes thermal polymerization reaction, photopolymerization reaction, radiation polymerization reaction, and the like. Examples of the polymerizable functional group possessed by the monomer having a polymerizable functional group include an acrylic group and a methacrylic group. A material having charge transport ability may be used as the monomer having a polymerizable functional group.
The protective layer may contain additives such as an antioxidant, an ultraviolet absorber, a plasticizer, a leveling agent, a lubricating agent, and an abrasion resistance improver. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, boron nitride particles. etc. The average film thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 7 μm or less.

The protective layer can be formed by preparing a protective layer coating liquid containing each of the materials and solvents described above, forming a coating film thereon, and drying and/or curing the coating film. Solvents used in the coating liquid include alcohol solvents, ketone solvents, ether solvents, sulfoxide solvents, ester solvents, and aromatic hydrocarbon solvents. In Example 1, the average film thickness of the protective layer was set to 3 μm.

In Example 2, the following materials were prepared.
・10 parts of the compound represented by the following formula (A-12) ・10 parts of the compound represented by the following formula (A-25) ・50 parts of 1-propanol ・1,1,2,2,3,3,4-hepta 25 parts of fluorocyclopentane (trade name: Zeorora H, manufactured by Nippon Zeon Co., Ltd.) These were mixed and stirred. Thereafter, this solution was filtered through a polyflon filter (trade name: PF-020, manufactured by Advantech Toyo Co., Ltd.) to prepare a protective layer coating solution.

This protective layer coating liquid was applied onto the charge transport layer by dip coating to form a coating film, and the resulting coating film was dried at 50° C. for 6 minutes. After that, in a nitrogen atmosphere, the coating film was irradiated with an electron beam for 1.6 seconds under conditions of an acceleration voltage of 70 kV and a beam current of 5.0 mA while rotating the support (object to be irradiated) at a speed of 200 rpm. In addition, when the absorption dose of the electron beam at this time was measured, it was 15 kGy. Thereafter, the temperature of the coating film was increased from 25° C. to 117° C. over 30 seconds in a nitrogen atmosphere to heat the coating film. The oxygen concentration from the electron beam irradiation to the subsequent heat treatment was 15 ppm or less. Next, the coating film was naturally cooled in the air until the temperature reached 25° C., and heat-treated for 30 minutes under the condition that the temperature of the coating film reached 105° C. to form a protective layer having a thickness of 3 μm. Thus, a cylindrical (drum-shaped) photoreceptor d having a support, an undercoat layer, a charge generation layer, a charge transport layer and a protective layer in this order was produced.

In the structure of Example 6, by using the photoreceptor d, which is the photoreceptor 1 provided with the protective layer, the abrasion of the surface of the photoreceptor 1 is reduced. That is, the surface potential formed on the photoreceptor 1 is stabilized. When the photoreceptor 1 of Example 6 is used, the metal soap 45c can be more stably maintained on the surface of the photoreceptor 1. FIG. Therefore, it is possible to suppress the occurrence of image deletion while maintaining the durability of the photoreceptor 1 even in a configuration with a longer life.

In Example 7, the surface of the photoreceptor 1 is roughened. In Examples 1 to 6, the case of using the photoreceptor 1 not subjected to the roughening treatment has been described. The metal soap 45c applied to the surface may be removed. This is because when the surface of the photoreceptor 1 has no unevenness, even if the metal soap 45c is applied to the surface of the photoreceptor 1, there is no catching such as a groove sufficient to hold the metal soap 45c. Therefore, in the case of a configuration having a longer life than in Examples 1 to 6, when the ability to supply the metal soap 45c decreases in the latter half of the life, the metal soap 45c can be stably applied to the surface of the photoreceptor 1 for a long period of time. was not possible.

Therefore, in the structure of Example 7, when the photoreceptor 1 subjected to an appropriate surface roughening treatment is used, the grooves formed on the surface of the photoreceptor 1 are filled with the metal soap 45c, and the metal soap 45c is not removed. It can remain on the surface of the photoreceptor 1 continuously. Therefore, the effect of the metallic soap application operation is sustained, and the metallic soap 45c can be stably applied to the surface of the photoreceptor 1 for a long period of time.

In order to achieve the effects as described above, the photoreceptor 1 that has been subjected to surface roughening treatment is used that satisfies the following conditions. The ten-point average surface roughness (Rz) of the peripheral surface of the photoreceptor 1 is 0<Rz≦0.70 (μm) (preferably 0.10≦Rz≦0.50 (μm)), and the peripheral surface The average interval (Sm) of the unevenness is 0<Sm≦70 (μm) (preferably 5≦Sm≦70 (μm)). By setting the content within the above range, the metal soap 45c can be stably maintained on the surface of the photoreceptor 1, and as a result, image deletion can be suppressed for a long period of time. Therefore, in the present embodiment, the surface of the photoreceptor 1 is roughened to form suitable unevenness, thereby maintaining the durability of the photoreceptor 1 even in a configuration with a longer life and using a simple configuration. , the image deletion is suppressed.

1. Roughening Treatment of Photoreceptor The photoreceptor 1 of the present embodiment is subjected to a roughening treatment for forming minute irregularities on the surface in order to maintain the effect of the metal soap 45c. According to Japanese Patent No. 4027407, a groove extending in the circumferential direction of the peripheral surface of the photosensitive member 1 and having a width of 0.5 μm or more and 40 μm or less is formed on the peripheral surface of the photosensitive member 1 in the longitudinal direction (generatrix direction, the photoconductor 1). It is formed so that it may line up in multiple numbers in the rotating shaft direction).

FIG. 18 shows an example of the state of the grooves 1b formed on the peripheral surface 1a of the photoreceptor 1. As shown in FIG. As shown in FIG. 18, each groove 1b is an annular groove extending in the circumferential direction on the peripheral surface 1a of the photoreceptor 1, and formed so as to be spaced apart from each other in the generatrix direction of the peripheral surface 1a. It is In other words, the peripheral surface 1a has a configuration in which flat portions 1c in which no grooves 1b are formed and grooves 1b are alternately formed in the generatrix direction. The area in which the groove 1b is formed on the peripheral surface 1a should include at least the area where the cleaning blade 8 contacts, and does not necessarily need to be formed over the entire length of the peripheral surface 1a.

In addition, as described in the above publication, the groove 1b is not limited to the structure formed so as to extend in the same direction as the circumferential direction as shown in FIG. For example, the groove 1b may be formed at an angle of 10° with respect to the circumferential direction. Alternatively, the grooves 1b may be formed at an angle of ±30° with respect to the circumferential direction, and the grooves 1b with different angles may cross each other. In the present embodiment, the term "substantially circumferential direction" includes both a complete circumferential direction and a substantially circumferential direction. is the direction of less than

Next, a polishing method for polishing the surface of the photoreceptor 1 will be described. FIG. 19 is a schematic diagram of a polishing device for polishing the surface of the photoreceptor 1. As shown in FIG. The polishing sheet 40 is wound in the direction of the arrow by a winding mechanism (not shown). Photoreceptor 1 rotates in the direction of the arrow. Backup roller 41 rotates in the direction of the arrow. As for the polishing conditions, a polishing sheet manufactured by Riken Corundum Co., Ltd. (trade name: GC#3000, base layer sheet thickness: 75 μm) was used as the polishing sheet 40 . A urethane roller (outer diameter: 50 mm) having a hardness of 20° is used as the backup roller 41, and the amount of penetration is 2.5 mm, and the sheet feed rate is 200 to 400 mm/s. were polished for 5 to 30 seconds while rotating in the same direction. The surface roughness of the photoreceptor 1 after polishing was measured under the following conditions using a surface roughness measuring instrument (trade name: SE700, SMB-9, manufactured by Kosaka Laboratory Ltd.). Measurements were taken at positions 30, 110 and 185 mm from the upper end of the coating in the longitudinal direction of the photoreceptor 1, rotated 120° forward, and then measured at positions 30, 110 and 185 mm from the upper end of the coating in the same manner. Further, after rotating 120° forward, measurements were taken in the same manner, and a total of 9 points were measured. Measurement conditions were as follows: measurement length: 2.5 mm, cutoff value: 0.8 mm, feed rate: 0.1 mm/s, filter characteristics: 2CR, leveling: straight line (whole area).

Table 7 shows the Rz and Sm of the photosensitive member 1 used in this example. Photoreceptors e to j in Table 7 were produced by changing the polishing time under the roughening treatment conditions. The photoreceptor k is the photoreceptor 1 used in Example 1, which is not roughened.

The ten-point average surface roughness (Rz) and the average spacing (Sm) of the unevenness of the peripheral surface of the photoreceptor 1 were determined based on the JIS standard (JIS B 0601) using a surface roughness measuring instrument manufactured by Kosaka Laboratory Co., Ltd. Using a surfcoder SE3500, measurements were made under the following conditions.
Detector: R2 μm
0.7 mN diamond stylus Filter: 2CR
Cutoff value: 0.8mm
Measurement length: 2.5mm
Feeding speed: 0.1mm

In this embodiment, 12 points in total, 4 points in the circumferential direction of each of the 3 points in the generatrix direction of the photosensitive member 1, are used as measurement points. As shown in FIG. 18, the average interval (Sm) of the unevenness of the peripheral surface of the photoreceptor 1 is the interval in the generatrix direction (longitudinal direction) of the plurality of grooves 1b arranged in the generatrix direction of the peripheral surface 1a, or the flat portion can be defined as the spacing in the generatrix direction (longitudinal direction) of 1c.

2. Effect on Application of Metallic Soap to Surface Roughened Photoreceptor Next, the role of the grooves formed in the photoreceptor 1 will be described. By forming the grooves on the surface of the photoreceptor 1, the metal soap 45c is filled in the grooves, and the metal soap 45c can remain on the surface of the photoreceptor 1 without being removed. Therefore, the effect of the metallic soap application operation is sustained, and the metallic soap 45c can be stably applied to the surface of the photoreceptor 1 for a long period of time. In order to achieve the effects as described above, the photoreceptor 1 that has been subjected to surface roughening treatment is used that satisfies the following conditions. The ten-point average surface roughness (Rz) of the peripheral surface of the photoreceptor 1 is 0<Rz≦0.70 (μm), and the average interval (Sm) of unevenness of the peripheral surface is 0<Sm≦70 (μm). is. By setting the content within the above range, the metal soap 45c can be stably maintained on the surface of the photoreceptor 1, and as a result, image deletion can be suppressed for a long period of time.

Photoreceptor i in Table 7 has Rz=0.75 (μm), and grooves are deeply formed on the surface of photoreceptor 1. Therefore, a large amount of metal soap 45c is required until the grooves are sufficiently filled. cannot perform. On the other hand, the result was good with Rz=0.68 (μm) of photoreceptor g in Table 7, so it was found that when Rz exceeds 0.70 (μm), the effect of the roughening treatment is weakened. Ta.

Further, since the photoreceptor j has Sm=78.5 (μm), the interval between the grooves is wide, and there are many portions where the grooves do not exist. I'm out. Therefore, even if the metallic soap application operation is performed, the metallic soap 45c cannot be stably maintained on the surface of the photoreceptor 1 for a long period of time. Since the results were good when Sm=67.3 (μm) of the photoreceptor h, it was found that when Sm exceeds 70.0 (μm), the effect of the roughening treatment is weakened.

On the other hand, it was found that formation of the grooves under the conditions of the photoreceptors e to h has a remarkable effect of suppressing image deletion. This is because the metal soap 45c can be held on the surface of the photoreceptor 1 by forming appropriate grooves on the surface of the photoreceptor 1 at appropriate intervals.

From the above results, it can be seen that the uneven shape of the surface of the photoreceptor 1 subjected to the surface roughening treatment in this example is such that the ten-point average surface roughness (Rz) of the peripheral surface is in the range of 0<Rz≦0.70 (μm). ), and the average interval of unevenness on the peripheral surface is 0<Sm≦70.0 (μm). Furthermore, preferably, the ten-point average surface roughness (Rz) of the peripheral surface is 0.10 ≤ Rz ≤ 0.50 (μm), and the average interval (Sm) of the unevenness of the peripheral surface is 5 ≤ Sm ≤ 70 ( μm). By setting 0.10≦Rz≦0.50 (μm) and 5≦Sm≦70 (μm), the unevenness works effectively, and the metal soap 45c is more likely to stay on the surface of the photoreceptor 1 . By using the photoreceptor 1 under the above conditions, the effect of the metallic soap application operation is maintained. As a result, the metal soap 45c can be stably maintained on the surface of the photoreceptor 1, and image smearing can occur with a simple structure while maintaining the durability of the photoreceptor even in a longer life structure. was able to be suppressed.

The configuration of this embodiment and the configuration of providing a protective layer on the surface of the photoreceptor 1 used in the sixth embodiment may be combined.

In Examples 1 to 7, the case of using a toner to which inorganic silicon fine particles are externally added as shown in FIG. 5 has been described. In Example 7, a case where the toner is changed and an organosilicon polymer toner having a surface layer containing an organosilicon polymer is used will be described.

In the case of using the toner externally added with inorganic silicon as in Examples 1 to 7, when an operation such as metallic soap application operation in which the friction between the photoreceptor 1 and the developing roller 4 is increased is executed, the inorganic silicon The silicon is removed from the toner. Inorganic silicon separated from the toner is supplied to the surface of the photoreceptor 1 together with the toner. Therefore, in the case of a long-life structure, the ability to apply the metal soap 45c is reduced in the latter half of the life. For the above reasons, it may not be possible to stably apply the metal soap 45c to the surface of the photoreceptor 1 for a long period of time when using the toner externally added with inorganic silicon.

However, when the organosilicon polymer toner is used as in this embodiment, the organosilicon polymer is less likely to be removed from the toner even by mechanical rubbing, and only the metallic soap 45c is efficiently removed from the photosensitive member 1 by the metallic soap coating operation. can be supplied to Therefore, the effect of the metallic soap application operation is sustained, and the metallic soap 45c can be stably applied to the surface of the photoreceptor 1 for a long period of time. In addition, since the organic silicon polymer in the surface layer can be used to control the charge of the toner and the physical properties of the toner, which are the inherent effects of adding inorganic silica externally, the image is hardly affected.

Therefore, in Example 8, by using an organosilicon polymer toner having a surface layer containing an organosilicon polymer, the durability of the photoreceptor 1 can be maintained even in a long-life configuration, and with a simple configuration, It is characterized by being configured to suppress the occurrence of image deletion. Note that the description of the portions overlapping those of Examples 1 to 7 will be omitted.

1. Toner Containing Organosilicon Polymer in Surface Layer In Example 8, a toner having toner particles and an organosilicon polymer having a structure represented by formula (1) described below and covering the surfaces of the toner particles was used. use.
R-SiO3/2 (1)
(R represents a hydrocarbon group having 1 to 6 carbon atoms.)

The surface of the toner particles is coated with an organosilicon polymer having a structure represented by formula (1) and has a surface layer which is the outermost layer of the toner particles. The surface layer is very hard compared to conventional toner particles. Therefore, from the viewpoint of fixability, a portion where the surface layer is not formed may be provided on a part of the surface of the toner particles. The ratio of the number of splitting axes in which the thickness of the surface layer containing the organosilicon polymer is 2.5 nm or less (hereinafter also referred to as the ratio of the thickness of the surface layer of 2.5 nm or less) is preferably 20.0% or less. . This condition approximates that at least 80.0% or more of the surface of the toner particles is composed of a surface layer containing an organosilicon polymer of 2.5 nm or more. That is, when this condition is satisfied, the surface layer containing the organosilicon polymer sufficiently covers the surface of the toner particles. More preferably, the proportion of the surface layer having a thickness of 2.5 nm or less is 10.0% or less. Measurement can be defined by cross-sectional observation using a transmission electron microscope (TEM). Details will be described later.

Next, the organosilicon polymer having the structure represented by formula (1) will be described. In the organosilicon polymer having the structure represented by formula (1), one of the four valences of Si atoms is bonded to R and the remaining three are bonded to O atoms. The O atom forms a state in which both of its two valences are bonded to Si, that is, a siloxane bond (Si--O--Si). Considering Si atoms and O atoms as an organosilicon polymer, since two Si atoms have three O atoms, it is expressed as -SiO3/2. Furthermore, in the chart obtained by 29Si-NMR measurement of the tetrahydrofuran (THF)-insoluble portion of the toner particles, the ratio of the peak area attributed to the structure of formula (1) to the total peak area of the organosilicon polymer is 20% or more. is preferably Although the detailed measurement method will be described later, this approximates that the organosilicon polymer contained in the toner particles has a partial structure represented by R--SiO3/2 in an amount of 20% or more.

As described above, the —SiO3/2 structure means that three of the four valences of Si atoms are bonded to oxygen atoms, and these oxygen atoms are bonded to other Si atoms. If one of the oxygens is a silanol group, the structure of the organosilicon polymer is represented by R--SiO2/2-OH. Furthermore, if two oxygens are silanol groups, the structure will be R--SiO1/2(--OH)2. Comparing these structures, more oxygen atoms forming a bridge structure with Si atoms is closer to the silica structure represented by SiO2. Therefore, the more the -SiO3/2 skeleton, the lower the surface free energy of the surface of the toner particles. In addition, due to the durability due to the structure represented by formula (1) and the hydrophobicity and chargeability of R in formula (1), a low molecular weight (= Mw: 1000 or less) that is present inside the surface layer and is easy to seep out ) and resins with a low glass transition temperature (Tg: 40° C. or lower) are prevented from bleeding. Bleeding of the release agent can also be suppressed in some cases.

The ratio of the peak area of the structure represented by formula (1) depends on the type and amount of the organosilicon compound used to form the organosilicon polymer, and the reaction temperature of hydrolysis, addition polymerization, and condensation polymerization during the formation of the organosilicon polymer. , reaction time, reaction solvent and pH. In the structure represented by formula (1), R is a hydrocarbon group having 1 to 6 carbon atoms. This tends to stabilize the charge amount. An aliphatic hydrocarbon group having 1 to 6 carbon atoms or a phenyl group, which is particularly excellent in environmental stability, is preferable. In the embodiment of the present invention, R is more preferably an aliphatic hydrocarbon group having 1 or more and 3 or less carbon atoms in order to further improve chargeability and antifogging. If the chargeability is good, the transferability is good and the amount of residual toner after transfer is small, so that the contamination of the photoreceptor 1 and the charging roller 2 is improved. Preferred examples of the aliphatic hydrocarbon group having 1 to 3 carbon atoms include methyl group, ethyl group, propyl group and vinyl group. From the viewpoint of environmental stability and storage stability, R is more preferably a methyl group. A sol-gel method is preferable as an example of the production of the organosilicon polymer. The sol-gel method is a method of hydrolyzing and condensation-polymerizing a liquid raw material as a starting raw material to form a sol state and then gelling, and is used in a method of synthesizing glasses, ceramics, organic-inorganic hybrids, and nanocomposites. By using this production method, functional materials in various shapes such as surface layers, fibers, bulk bodies, and fine particles can be produced from the liquid phase at a low temperature. Specifically, the organosilicon polymer present on the surface layer of the toner particles is preferably produced by hydrolysis and polycondensation of a silicon compound represented by alkoxysilane. By providing the surface layer containing the organosilicon polymer on the toner particles, the environmental stability is improved, the performance of the toner is less likely to deteriorate during long-term use, and a toner excellent in storage stability can be obtained. .

Furthermore, the sol-gel method starts from a liquid and forms a material by gelling the liquid, so various microstructures and shapes can be produced. In particular, when the toner particles are produced in an aqueous medium, the particles are easily precipitated on the surface of the toner particles due to the hydrophilicity of the hydrophilic group such as the silanol group of the organosilicon compound. The fine structure and shape can be adjusted by the reaction temperature, reaction time, reaction solvent, pH, the type and amount of the organometallic compound, and the like. The organosilicon polymer is preferably a condensation polymer of an organosilicon compound having a structure represented by formula (Z) below.

（式（Ｚ）中、Ｒ１は、炭素数１以上６以下の炭化水素基を表し、Ｒ２、Ｒ３及びＲ４は、それぞれ独立して、ハロゲン原子、ヒドロキシ基、アセトキシ基、又は、アルコキシ基を表す。）

(In the formula (Z), R1 represents a hydrocarbon group having 1 to 6 carbon atoms, and R2, R3 and R4 each independently represents a halogen atom, a hydroxy group, an acetoxy group, or an alkoxy group. .)

Hydrophobicity can be improved by the hydrocarbon group (preferably alkyl group) of R1, and toner particles with excellent environmental stability can be obtained. In addition, an aryl group that is an aromatic hydrocarbon group such as a phenyl group can also be used as the hydrocarbon group. When the hydrophobicity of R1 is large, the charge amount tends to increase in various environments. Therefore, in view of environmental stability, R1 is preferably an aliphatic hydrocarbon group having 1 to 3 carbon atoms. A methyl group is more preferred. That is, it is preferable that the number of carbon atoms directly bonded to silicon atoms in the organosilicon polymer is 1 or more and 3 or less. R2, R3 and R4 are each independently a halogen atom, a hydroxy group, an acetoxy group or an alkoxy group (hereinafter also referred to as a reactive group). These reactive groups form a crosslinked structure through hydrolysis, addition polymerization, and condensation polymerization, and a toner excellent in member contamination resistance and development durability can be obtained. From the viewpoint of moderate hydrolyzability at room temperature and deposition and coating properties on the surface of toner particles, an alkoxy group having 1 to 3 carbon atoms is preferable, and a methoxy group or an ethoxy group is more preferable. preferable. Also, the hydrolysis, addition polymerization and condensation polymerization of R2, R3 and R4 can be controlled by reaction temperature, reaction time, reaction solvent and pH.

In order to obtain the organosilicon polymer used in the embodiment of the present invention, an organosilicon compound ( hereinafter also referred to as trifunctional silane) may be used singly or in combination. Examples of the above formula (Z) include the following.

Methyltrimethoxysilane, Methyltriethoxysilane, Methyldiethoxymethoxysilane, Methylethoxydimethoxysilane, Methyltrichlorosilane, Methylmethoxydichlorosilane, Methylethoxydichlorosilane, Methyldimethoxychlorosilane, Methylmethoxyethoxychlorosilane, Methyldiethoxychlorosilane, Methyl triacetoxysilane, methyldiacetoxymethoxysilane, methyldiacetoxyethoxysilane, methylacetoxydimethoxysilane, methylacetoxymethoxyethoxysilane, methylacetoxydiethoxysilane, methyltrihydroxysilane, methylmethoxydihydroxysilane, methylethoxydihydroxysilane, methyldimethoxysilane trifunctional methylsilanes such as hydroxysilane, methylethoxymethoxyhydroxysilane, methyldiethoxyhydroxysilane;

ethyltrimethoxysilane, ethyltriethoxysilane, ethyltrichlorosilane, ethyltriacetoxysilane, ethyltrihydroxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltrichlorosilane, propyltriacetoxysilane, propyltrihydroxysilane, butyltri Trifunctional such as methoxysilane, butyltriethoxysilane, butyltrichlorosilane, butyltriacetoxysilane, butyltrihydroxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, hexyltrichlorosilane, hexyltriacetoxysilane, hexyltrihydroxysilane sex silane.

Trifunctional phenylsilanes such as phenyltrimethoxysilane, phenyltriethoxysilane, phenyltrichlorosilane, phenyltriacetoxysilane, phenyltrihydroxysilane.

In addition to the organosilicon compound having the structure represented by the formula (Z), an organosilicon polymer obtained by combining the following may be used to the extent that the effects of this example are not impaired. Organosilicon compounds with four reactive groups in one molecule (tetrafunctional silane), organosilicon compounds with two reactive groups in one molecule (bifunctional silane), or organosilicon compounds with one reactive group (difunctional silane) monofunctional silane). For example:

dimethyldiethoxysilane, tetraethoxysilane, hexamethyldisilazane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriemethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-amino ethyl)aminopropyltriethoxysilane, vinyltriisocyanatesilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyldiethoxymethoxysilane, vinylethoxydimethoxysilane, vinylethoxydihydroxysilane, vinyldimethoxyhydroxysilane, vinylethoxymethoxyhydroxysilane, Trifunctional vinylsilanes, such as vinyldiethoxyhydroxysilane.

Furthermore, the content of the organosilicon polymer in the toner particles is preferably 0.5% by mass or more and 10.5% by mass or less. When the content of the organosilicon polymer is 0.5% by mass or more, the surface free energy of the surface layer can be further reduced, the fluidity can be improved, and the contamination of the member and the occurrence of fogging can be suppressed. . When it is 10.5% by mass or less, charge-up can be made difficult to occur. The content of the organosilicon polymer is controlled by the type and amount of the organosilicon compound used to form the organosilicon polymer, the method of producing toner particles during the formation of the organosilicon polymer, reaction temperature, reaction time, reaction solvent and pH. can be done. It is preferable that the surface layer containing the organosilicon polymer and the toner core particles are in contact without any gap. As a result, the occurrence of bleeding caused by the resin component, release agent, etc. inside the toner particles is suppressed from the surface layer of the toner particles, and a toner excellent in storage stability, environmental stability and development durability can be obtained. In addition to the organosilicon polymer described above, the surface layer may contain resins such as styrene-acrylic copolymer resins, polyester resins and urethane resins, and various additives.

2. Method for Confirming Partial Structure by NMR Measurement Next, a method for confirming the partial structure of toner particles by NMR measurement will be described. The tetrahydrofuran (THF) insolubles of the toner particles described above were prepared as follows. 10.0 g of toner particles are weighed, placed in a thimble (No. 86R manufactured by Toyo Roshi Kaisha Ltd.), and placed in a Soxhlet extractor. Extraction was performed using 200 mL of THF as a solvent for 20 hours, and the filter cake in the thimble was vacuum-dried at 40° C. for several hours. When the surface of the toner particles is treated with an external additive or the like, the external additive is removed by the following method to obtain toner particles.

160 g of sucrose (manufactured by Kishida Chemical Co., Ltd.) is added to 100 mL of ion-exchanged water and dissolved in a hot water bath to prepare a concentrated sucrose solution. In a centrifugation tube (capacity: 50 mL), 31 g of the concentrated sucrose solution and Contaminon N (a pH 7 neutral detergent for cleaning precision measuring instruments consisting of a nonionic surfactant, an anionic surfactant, and an organic builder) were added. 6 mL of a mass % aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) is added to prepare a dispersion. 1.0 g of toner is added to this dispersion, and clumps of toner are loosened with a spatula or the like.

The centrifuge tube is shaken on a shaker at 350 spm (strokes per min) for 20 minutes. After shaking, the solution is transferred to a swing rotor glass tube (capacity 50 mL) and separated in a centrifuge (manufactured by H-9R Kokusan Co., Ltd.) at 3500 rpm for 30 minutes. This operation separates the toner particles from the detached external additive. It is visually confirmed that the toner and the aqueous solution are sufficiently separated, and the separated toner on the uppermost layer is collected with a spatula or the like. After filtering the collected toner with a vacuum filter, it is dried with a dryer for 1 hour or longer to obtain toner particles. This operation is carried out multiple times to ensure the required amount.

The following method is used to confirm the partial structure represented by formula (1) in the organosilicon polymer contained in the toner particles. The hydrocarbon group represented by R in formula (1) was confirmed by 13C-NMR.

<< ¹³ C-NMR (solid) measurement conditions>>
Device: JNM-ECX500II manufactured by JEOLRESONANCE
Sample tube: 3.2 mmφ
Sample: 150 mg of tetrahydrofuran-insoluble matter of toner particles for NMR measurement
Measurement temperature: Room temperature Pulse mode: CP/MAS
Measurement nuclear frequency: 123.25 MHz ( ¹³ C)
Reference substance: adamantane (external standard: 29.5 ppm)
Sample rotation speed: 20 kHz
Contact time: 2ms
Delay time: 2s
Cumulative number: 1024 times Methyl group (Si—CH ₃ ), ethyl group (Si—C ₂ H ₅ ), propyl group (Si—C ₃ H ₇ ), butyl group bonded to silicon atom by the above method (Si--C ₄ H ₉ ), pentyl group (Si--C ₅ H ₁₁ ), hexyl group (Si--C ₆ H ₁₃ ) or phenyl group (Si--C ₆ H ₅ --). , confirmed the hydrocarbon group represented by R in formula (1). Next, a method for calculating the ratio of the peak area attributed to the structure of formula (1) in the organosilicon polymer contained in the toner particles will be described.

²⁹ Si-NMR (solid) measurement of the THF-insoluble portion of the toner particles is performed under the following measurement conditions.
<< ²⁹ Si-NMR (solid) measurement conditions >>
Device: JNM-ECX500II manufactured by JEOLRESONANCE
Sample tube: 3.2 mmφ
Sample: 150 mg of tetrahydrofuran-insoluble matter of toner particles for NMR measurement
Measurement temperature: Room temperature Pulse mode: CP/MAS
Measured nuclear frequency: 97.38 MHz ( ²⁹ Si)
Reference substance: DSS (external standard: 1.534 ppm)
Sample rotation speed: 10 kHz
Contact time: 10ms
Delay time: 2s
Accumulated times: 2000 to 8000 times

After the above measurement, a plurality of silane components having different substituents and bonding groups in the tetrahydrofuran-insoluble portion of the toner particles were peak-separated into the following X1 structure, X2 structure, X3 structure, and X4 structure by curve fitting. Calculate area.
X1 structure: (Ri) (Rj) (Rk) SiO _1/2 Formula (2)
X2 structure: (Rg)(Rh)Si(O _1/2 ) ₂ Formula (3)
X3 structure: RmSi(O _1/2 ) ₃ Formula (4)
X4 structure: Si(O _1/2 ) ₄ Formula (5)

（式（２）、（３）及び（４）中のＲｉ、Ｒｊ、Ｒｋ、Ｒｇ、Ｒｈ、Ｒｍはケイ素に結合している、炭素数１～６の炭化水素基などの有機基、ハロゲン原子、ヒドロキシ基、アセトキシ基又はアルコキシ基を示す。）

(Ri, Rj, Rk, Rg, Rh, and Rm in formulas (2), (3), and (4) are bonded to silicon, organic groups such as hydrocarbon groups having 1 to 6 carbon atoms, halogen atoms , indicates a hydroxy group, an acetoxy group, or an alkoxy group.)

In the embodiment of the present invention, in the chart obtained by ²⁹ Si-NMR measurement of the THF-insoluble portion of the toner particles, the ratio of the peak area attributed to the structure of formula (1) to the total peak area of the organosilicon polymer It is preferable that the ratio is 20% or more.

If it is necessary to confirm the structure represented by the above formula (1) in more detail, it may be identified by the measurement results of ¹ H-NMR together with the measurement results of ¹³ C-NMR and ²⁹ Si-NMR.

3. Method for Measuring Surface Layer Thickness by Cross-Sectional Observation of Toner Particle Next, the percentage of the surface layer containing the organosilicon polymer having a thickness of 2.5 nm or less, which is measured by cross-sectional observation of the toner particles using a transmission electron microscope (TEM). will be explained. In this embodiment, observation of the cross section of the toner particles is performed by the following method.

After sufficiently dispersing the toner particles in the room temperature curable epoxy resin, the resin is cured in an atmosphere of 40° C. for 2 days. A flaky sample is cut from the obtained cured product using a microtome equipped with diamond teeth. This sample is magnified by a magnification of 10,000 to 100,000 times with a transmission electron microscope (JEM-2800 manufactured by JEOL) (TEM) to observe the cross section of the toner particles. This can be confirmed by utilizing the difference in atomic weight between the binder resin and the surface layer material, and by utilizing the fact that the higher the atomic weight, the brighter the contrast. Ruthenium tetroxide staining and osmium tetroxide staining are used to provide contrast between materials. For the particles used for the measurement, the circle-equivalent diameter Dtem is determined from the cross section of the toner particles obtained from the above-mentioned TEM micrograph, and the value is included in the range of ±10% of the weight-average particle diameter D4 of the toner particles. do.

As described above, using JEM-2800 manufactured by JEOL, a dark field image of the cross section of the toner particles is obtained at an accelerating voltage of 200 kV. Next, using an EELS detector GIFQuantam manufactured by Gatan, a mapping image is acquired by the Three Window method to confirm the surface layer.

Next, for one toner particle whose circle-equivalent diameter Dtem is within ±10% of the weight-average particle diameter D4 of the toner particle, As shown in FIG. 20, the cross section of the toner particles is evenly divided into 16 with the intersection point of the axis L90 as the center. Next, let An (n=1 to 32) be the division axis extending from the center to the surface layer of the toner particle, RAn be the length of the division axis, and FRAn be the thickness of the surface layer. Then, the ratio of the number of dividing axes having a surface layer containing the organosilicon polymer having a thickness of 2.5 nm or less among the 32 dividing axes is determined. For averaging, 10 toner particles are measured and the average per toner particle is calculated.

The circle equivalent diameter (Dtem) obtained from the cross section of the toner particles obtained from the TEM photograph is obtained by the following method. First, for one toner particle, the equivalent circle diameter Dtem obtained from the cross section of the toner particle obtained from the TEM photograph is obtained according to the following formula.

[Circle equivalent diameter (Dtem) obtained from the cross section of toner particles obtained from a TEM photograph]=(RA1+RA2+RA3+RA4+RA5+RA6+RA7+RA8+RA9+RA10+RA11+RA12+RA13+RA14+RA15+RA16+RA17+RA18+RA19+RA20+RA21+RA22+RA23+RA24+RA25+RA26+RA 27+RA28+RA29+RA30+RA31+RA32)/16
Equivalent circle diameters of 10 toner particles are obtained, and the average value per particle is calculated as the equivalent circle diameter (Dtem) obtained from the cross section of the toner particles.

The proportion of the surface layer containing the organosilicon polymer having a thickness of 2.5 nm or less is expressed by the following formula.
[Percentage of surface layer containing organosilicon polymer having thickness (FRAn) of 2.5 nm or less]=[{Number of splitting axes having surface layer containing organosilicon polymer having thickness (FRAn) of 2.5 nm or less] }/32]×100

This calculation was performed for 10 toner particles, and the average value of the percentage of the 10 toner particles having a surface layer thickness (FRAn) of 2.5 nm or less was obtained. A ratio of 5 nm or less was used.

4. Toner Manufacturing Method Hereinafter, the toner used in Example 8 will be specifically described, but the toner is not limited to these Examples. All "parts" of each material in Examples and Comparative Examples are based on mass unless otherwise specified.

First, the preparation process of the aqueous medium 1 will be described. To 1000.0 parts of ion-exchanged water in a reaction vessel, 14.0 parts of sodium phosphate (12 hydrate, manufactured by Rasa Kogyo Co., Ltd.) was added, and the mixture was kept at 65° C. for 1.0 hour while purging with nitrogen. T. K. Using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), while stirring at 12000 rpm, a calcium chloride aqueous solution obtained by dissolving 9.2 parts of calcium chloride (dihydrate) in 10.0 parts of ion-exchanged water is mixed together. to prepare an aqueous medium containing a dispersion stabilizer. Furthermore, 10% by mass hydrochloric acid was added to the aqueous medium to adjust the pH to 5.0, and an aqueous medium 1 was obtained.

Next, the hydrolysis step of the organosilicon compound for the surface layer will be described. 60.0 parts of ion-exchanged water was weighed into a reactor equipped with a stirrer and a thermometer, and the pH was adjusted to 3.0 using 10% by mass hydrochloric acid. This was heated with stirring to bring the temperature to 70°C. Thereafter, 40.0 parts of methyltriethoxysilane, which is an organosilicon compound for the surface layer, was added and hydrolyzed by stirring for 2 hours or more. The end point of the hydrolysis was visually confirmed by confirming that the oil and water did not separate and became one layer, and then cooled to obtain a hydrolyzate of the organosilicon compound for the surface layer.

In the case of forming the surface layer containing the organosilicon polymer as in this embodiment, in the case of forming the toner particles in the aqueous medium, the organosilicon polymer is formed as described above while performing the polymerization process described later in the aqueous medium. A surface layer can be formed by adding a hydrolyzate of the compound. A surface layer may be formed by adding a hydrolyzate of an organosilicon compound to a dispersion of toner particles after polymerization as a dispersion of core particles. In the case of a kneading pulverization method other than an aqueous medium, the obtained toner particles are dispersed in an aqueous medium and used as a core particle dispersion, and the hydrolyzate of the organosilicon compound is added as described above to form a surface layer. can be formed.

Next, the preparation process of the polymerizable monomer composition will be described.
- Styrene 60.0 parts - C.I. I. Pigment Blue 15:3 6.5 parts The above materials are put into an attritor (manufactured by Mitsui Miike Kakoki Co., Ltd.), and further dispersed using zirconia particles with a diameter of 1.7 mm at 220 rpm for 5.0 hours to disperse the pigment. A liquid was prepared. The following materials were added to the pigment dispersion.
・Styrene 20.0 parts ・n-butyl acrylate 20.0 parts ・Crosslinking agent (divinylbenzene) 0.3 parts ・Saturated polyester resin 5.0 parts (propylene oxide-modified bisphenol A (2 mol adduct) and terephthalic acid (molar ratio 10:12), glass transition temperature Tg = 68 ° C., weight average molecular weight Mw = 10000, molecular weight distribution Mw / Mn = 5.12)
- 7.0 parts of Fischer-Tropsch wax (melting point 78°C). K. A homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) was used to uniformly dissolve and disperse at 500 rpm to prepare a polymerizable monomer composition.

Next, the granulation process will be described. The temperature of the aqueous medium 1 is set at 70°C, T.E. K. While maintaining the rotation speed of the homomixer at 12000 rpm, the polymerizable monomer composition was charged into the aqueous medium 1, and 9.0 parts of t-butyl peroxypivalate as a polymerization initiator was added. The mixture was granulated for 10 minutes while maintaining 12000 rpm with a stirring device.

Next, the polymerization process will be explained. After the granulation step, the agitator was changed to a propeller agitating blade, and while stirring at 150 rpm, the mixture was maintained at 70°C and polymerized for 5.0 hours. core particles were obtained. When the temperature of the slurry was cooled to 55° C. and the pH was measured, it was pH=5.0. While stirring was continued at 55° C., 20.0 parts of the hydrolyzate of the organosilicon compound for the surface layer was added to start forming the surface layer of the toner. After holding for 30 minutes as it is, the slurry was adjusted to pH=9.0 for completion of condensation using an aqueous sodium hydroxide solution and held for an additional 300 minutes to form a surface layer.

Finally, the washing and drying steps will be explained. After completion of the polymerization process, the slurry of toner particles is cooled, and hydrochloric acid is added to the slurry of toner particles to adjust the pH to 1.5 or less, and the mixture is left with stirring for 1 hour, followed by solid-liquid separation with a pressurized filter to form a toner cake. got This was reslurried with ion-exchanged water to form a dispersion again, and then subjected to solid-liquid separation with the aforementioned filter. After reslurry and solid-liquid separation were repeated until the electrical conductivity of the filtrate became 5.0 μS/cm or less, solid-liquid separation was finally performed to obtain a toner cake. The resulting toner cake was dried with a flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.). The drying conditions were a blowing temperature of 90.degree. C., a dryer outlet temperature of 40.degree.

Silicon mapping is performed in cross-sectional TEM observation of toner particles 1, and the presence of silicon atoms in the surface layer and the ratio of the number of splitting axes having a thickness of 2.5 nm or less in the surface layer of the toner particles containing the organosilicon polymer are It was confirmed to be 20.0% or less. In this example, the obtained toner particles were used as the toner of Example 8 as they were without externally adding inorganic silicon at least.

The fixation rate of the organosilicon polymer having the structure represented by formula (1) covering the surfaces of the toner particles is preferably 30% or more and 100% or less. This is because the increase in the area of the surface layer where the organosilicon polymer does not exist increases the adhesion force between the toner particles and changes the chargeability.

In Example 8, a toner in which the surfaces of the toner particles are coated with the organic silicon polymer is used instead of externally adding the organic silicon polymer or the inorganic silicon fine particles to the base particles. Since the organosilicon polymer is less likely to come off from the toner (higher fixation rate) than when externally added toner is used, only the metal soap 45c can be efficiently supplied to the photoreceptor 1. It is possible to further maintain the image deletion suppressing effect.

5. Confirmation of Effect of Toner Particles Using Organosilicon Polymer In Example 8, toners b to e were prepared by using the above-described toner production method so that the fixation ratio of the organosilicon polymer coating the surface of the toner particles was different. prepared. The fixation rate varies depending on the toner manufacturing conditions. In this example, toners with different fixation rates were produced by changing the conditions for adding the hydrolyzate in the polymerization step and the holding time after the addition. In addition, pH adjustment was performed with hydrochloric acid and sodium hydroxide aqueous solution. Table 8 shows conditions for producing toners with different fixing rates. Further, in the toners b to e produced by the above method, 0.20% by mass of zinc stearate was externally added as the metal soap 45c in the same manner as in Example 1. However, with respect to Toner e, the hydrolysis step of the organosilicon compound for the surface layer was not performed. Instead, 30 parts of methyltriethoxysilane, which is an organosilicon compound for the surface layer, was added as a monomer in the process of preparing the polymerizable monomer composition. In the polymerization step, the hydrolyzate was not added after cooling to 70° C. and measuring the pH. While continuing to stir at 70° C., the slurry was adjusted to pH=9.0 for completion of condensation using an aqueous sodium hydroxide solution and held for an additional 300 minutes to form a surface layer.

If the fixation rate of the organosilicon polymer is high, the organosilicon polymer is less likely to be supplied to the grooves on the surface of the photoreceptor 1 and the metal soap 45c is more likely to be supplied to the grooves on the surface of the photoreceptor 1 . This is because the organosilicon polymer is less likely to come off from the toner, and only the metal soap 45c can be efficiently supplied to the photoreceptor 1 by the metal soap coating operation. As in the toners b to d of this embodiment, by setting the fixation rate of the organosilicon polymer to 90% or more, it becomes possible to positively supply the metal soap 45c onto the surface of the photoreceptor 1 . Compared to toner e in which the fixation rate of the organosilicon polymer is 85%, the effect of the metallic soap application operation is even greater. Therefore, the effect of the metal soap 45c for suppressing image deletion by the metal soap application operation is sustained, and the metal soap 45c can be stably applied to the surface of the photoreceptor 1 for a long period of time.

In the configuration of Example 8, by using the organosilicon polymer toner having the surface layer containing the organosilicon polymer, the effect of suppressing the image deletion of the metallic soap 45c due to the metallic soap application operation is maintained.

As a result, the metal soap 45c can be stably maintained on the surface of the photoreceptor 1, and the durability of the photoreceptor 1 can be maintained even in a configuration with a longer service life. It is possible to suppress the occurrence.

In addition, although reversal development is used in Examples 1 to 7, the present invention is not limited to this, and normal development may be used. In Examples 1 to 7, the negatively charged photoreceptor 1 was used, but the present invention is not limited to this, and a positively charged photoreceptor may be used.

Further, although a color laser printer is used as the image forming apparatus 100 in Embodiments 1 to 7, the image forming apparatus 100 having a single cartridge structure such as a monochrome laser printer may also be used.

Further, instead of the intermediate transfer method using the intermediate transfer belt 31, a method of directly transferring the toner image formed on the surface of the photoreceptor 1 onto the recording material S may be used.

In addition, the setting conditions used as explanations in Examples 1 to 7 are examples, and are not limited thereto.

REFERENCE SIGNS LIST 1 photoreceptor 2 charging roller 3c toner storage section 4 developing roller 10 toner 36 charging current detection section 45c metal soap 71 charging voltage application section 100 image forming apparatus 202 control section

Claims (18)

In an image forming apparatus that forms a toner image on a recording material,
a rotatable image carrier;
a charging member that charges the surface of the image carrier;
a toner containing portion containing a toner containing a metallic soap;
a developing member that forms a toner image by supplying the toner to the surface of the image carrier charged by the charging member in a developing section facing the image carrier;
a voltage applying unit that applies a charging voltage to the charging member;
a current detection unit that detects a current flowing from the charging member to the image carrier while the charging voltage is applied to the voltage application unit;
and a control unit that controls the voltage application unit,
an image forming operation for forming the toner image on a recording material; and an operation different from the image forming operation, in which the toner contained in the toner container is supplied from the developing member to the surface of the image carrier. and an application operation of applying the metallic soap to the surface of the image carrier by:
When the current value of the current detected by the current detection unit is the first current value, the application operation is not performed, and a second current value having a larger absolute value than the first current value is selected. An image forming apparatus characterized by executing the coating operation in some cases. 2. The image forming apparatus according to claim 1, wherein the application operation is performed when a current value of the current detected by the current detection unit exceeds a predetermined threshold. In a state where the surface moving speed of the developing member is higher than the surface moving speed of the image carrier, the speed difference between the surface moving speed of the image carrier and the surface moving speed of the developing member in the coating operation is the image forming operation. 3. The image forming apparatus according to claim 1, wherein control is performed so as to be larger than the speed difference at . 4. The image forming apparatus according to claim 1, wherein in the coating operation, the developing member contacts the image carrier at the developing portion. an information detection unit for detecting usage information of the image carrier and the charging member;
When the usage information detected by the information detection unit is the second usage information detected to be more used than the first usage information, it is more likely to be used than the first usage information. 3. The image forming apparatus according to claim 2, wherein an absolute value of said threshold value is set large. a first exposure unit that exposes the surface of the image carrier charged by the charging member;
a transfer member that forms a transfer portion in contact with the image carrier and transfers the toner image formed on the surface of the image carrier at the transfer portion;
exposing the surface of the image carrier on the downstream side of the transfer section in the rotation direction of the image carrier and on the upstream side of the charging section on the surface of the image carrier charged by the charging member; and a second exposure unit to
The information on the use information includes information on the film thickness of the image carrier, information on the exposure amount exposed by the first exposure section, information on the exposure amount exposed by the second exposure section, 6. The image forming apparatus according to claim 5 , wherein the calculation is performed using at least one of the number of images to be formed, the rotation speed of the image carrier, and the voltage application time by the voltage application unit. The information about the exposure amount exposed by the first exposure section and the information about the exposure amount exposed by the second exposure section are the irradiation time and the irradiation intensity of the exposure by the first exposure section, and the second exposure section. 7. The image forming apparatus according to claim 6 , wherein the calculation is performed using at least one of an irradiation time and an irradiation intensity for exposure by the exposing unit of . The range of the ten-point average surface roughness (Rz) of the surface of the image carrier is 0.10≦Rz≦0.70 (μm), and the average interval (Sm) of the unevenness of the surface of the image carrier is ) is 0<Sm≦ 70 (μm). The toner contains an organosilicon polymer,
9. The image forming apparatus according to claim 1, wherein the number of carbon atoms directly bonded to the silicon atoms of the organosilicon polymer is 1 to 3. 10. The image forming apparatus according to claim 9 , wherein the organosilicon polymer has a partial structure represented by R--SiO3/2 (R represents a hydrocarbon group having 1 to 6 carbon atoms). . 11. The image forming apparatus according to claim 10 , wherein said R is a hydrocarbon group having from 1 to 3 carbon atoms. a first voltage applying unit for applying the charging voltage to the charging member, and a second voltage applying unit for applying the developing voltage to the developing member;
When the difference between the surface potential of the surface of the image carrier charged by the charging member in the developing section and the developing voltage applied to the developing member by the second voltage applying section is defined as back contrast 12. The image forming apparatus according to any one of claims 1 to 11 , wherein the control unit performs control so that the back contrast in the coating operation is higher than the back contrast in the image forming operation. Device. 13. The image forming apparatus according to claim 1 , wherein the metal soap contains at least one of zinc, calcium, and magnesium. 14. The image forming apparatus according to claim 1, wherein the metal soap is at least one of zinc stearate, calcium stearate, and magnesium stearate. The image forming apparatus according to any one of claims 1 to 14 , wherein the metallic soap has a particle size of 0.15 µm or more and 2.0 µm or less. 16. The image forming apparatus according to any one of claims 1 to 15 , wherein the image carrier has a protective layer made of an acrylic resin as an outermost layer. 17. The image forming apparatus according to claim 16 , wherein the protective layer is a cured film that polymerizes a composition containing a monomer having a polymerizable functional group. 3. The image forming apparatus according to claim 2, wherein the threshold value increases as the absolute value of the charging voltage applied to the charging member increases in the image forming operation.

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