JP6303573B2 - Charging device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a charging device, a process cartridge, and an image forming apparatus.

  In an image forming apparatus using an electrophotographic method, first, a laser beam that modulates an image signal by forming a charge on the surface of an image carrier made of a photoconductive photoreceptor containing an inorganic or organic material by using a charging device. After the electrostatic latent image is formed, the electrostatic latent image is developed with a charged toner to form a visualized toner image. Then, the toner image is electrostatically transferred to a transfer material such as recording paper through an intermediate transfer member or directly, and fixed on the recording material, whereby a reproduced image is obtained.

In Patent Document 1, in a charging roll that contacts a member to be charged and is charged by applying a voltage, the component value of the surface free energy of the surface layer of the charging roll is γ _s ^d <30 mN / m, γ _s. An image forming apparatus provided with a charging roll characterized in that ^p <20 mN / m and the ten-point average roughness of the surface is 2.0 μm or less is disclosed.

JP 2002-169355 A

  An object of the present invention is to provide a charging device capable of suppressing streak-like image defects.

The above problem is solved by the following means. That is,
The invention according to claim 1
A conductive support, a conductive elastic layer provided on the outer peripheral surface of the conductive support, and provided on the outer peripheral surface of the conductive elastic layer, the surface free energy is 50 mN / m or more and 90 mN / m or less A roll-shaped charging member having a conductive surface layer, and
A support and a foamed elastic layer provided on the outer peripheral surface of the support and having a number of foam cells of 40 to 75 per 25 mm, and contact the conductive surface layer of the charging member. And a roll-shaped cleaning member that rotates.

The invention according to claim 2
The charging device according to claim 1, wherein the conductive surface layer in the charging member includes porous resin particles and silicone oil.

The invention according to claim 3
The charging device according to claim 2, wherein the silicone oil is at least one selected from the group consisting of a polyether-modified silicone oil and a polyester-modified silicone oil.

The invention according to claim 4
4. The charging device according to claim 2, wherein the foamed elastic layer in the cleaning member contains a silicone compound having the same modified site as the silicone oil contained in the conductive surface layer in the charging member.

The invention according to claim 5
5. The charging device according to claim 1, wherein a surface roughness Rz of the conductive surface layer in the charging member is 2.0 μm or more and 10.0 μm or less.

The invention according to claim 6
The charging device according to any one of claims 1 to 5, wherein the foamed elastic layer in the cleaning member is a urethane foam layer.

The invention according to claim 7 provides:
An image carrier,
The charging device according to any one of claims 1 to 6, comprising a charging member and a cleaning member, and charging the image holding member by bringing the charging member into contact with the image holding member.
And a process cartridge that can be attached to and detached from the image forming apparatus.

The invention according to claim 8 provides:
Claim conductive surface layer in the charging member comprises a silicone oil, a layer on the surface of the image carrier is, containing a silicone oil having the same modified cite silicone oil with the previous Kishirube conductive surface layer 7. The process cartridge according to 7.

The invention according to claim 9 is:
An image carrier,
The charging device according to any one of claims 1 to 6, comprising a charging member and a cleaning member, and charging the image holding member by bringing the charging member into contact with the image holding member.
A latent image forming apparatus for forming a latent image on the surface of the charged image carrier;
A developing device for developing a latent image formed on the surface of the image carrier with toner to form a toner image;
A transfer device for transferring the toner image formed on the surface of the image carrier to a recording medium;
An image forming apparatus.

The invention according to claim 10 is:
Claim conductive surface layer in the charging member comprises a silicone oil, a layer on the surface of the image carrier is, containing a silicone oil having the same modified cite silicone oil with the previous Kishirube conductive surface layer 9. The image forming apparatus according to 9.

According to the invention described in claim 1, a roll-shaped charging member in which the surface free energy of the conductive surface layer is less than 50 mN / m is used, or a roll in which the number of foamed cells in the foamed elastic layer is out of the above range. A charging device that can suppress streak-like image defects is provided as compared to the case where a cleaning member in the form of a stripe is used.
According to the second aspect of the present invention, there is provided a charging device in which the conductive surface layer in the charging member can suppress streak-like image defects as compared with the case where the porous resin particles and the silicone oil are not used in combination. .
According to the third aspect of the present invention, the charging device can suppress streak-like image defects as compared with the case where the conductive surface layer in the charging member contains a silicone oil other than the polyether-modified silicone oil and the polyester-modified silicone oil. Is provided.
According to the invention of claim 4, when the foamed elastic layer in the cleaning member is a silicone compound having a modified site different from the silicone oil contained in the conductive surface layer in the charging member, the image resulting from the charging member after storage Provided is a charging device in which the occurrence of defects is suppressed.
According to the fifth aspect of the present invention, there is provided a charging device capable of suppressing streak-like image defects as compared with the case of using a charging member whose surface roughness of the conductive surface layer is out of the above range.
According to the invention which concerns on Claim 6, compared with the case where the foaming elastic layer in a cleaning member is a melamine foaming layer, the charging device which can suppress a stripe-like image defect is provided.

According to the invention according to claim 7 or 9, a roll-shaped charging member in which the surface free energy of the conductive surface layer is less than 50 mN / m is used, or the number of foamed cells of the foamed elastic layer is out of the above range. A process cartridge or an image forming apparatus capable of suppressing streak-like image defects is provided as compared with a case where a charging device using a roll-shaped cleaning member is provided.
According to the invention according to claim 8 or 10, the layer present on the surface of the image carrier is stored as compared with a case where the layer is a silicone oil having a modified portion different from the silicone oil included in the conductive surface layer of the charging member. There is provided a process cartridge or an image forming apparatus in which occurrence of image defects due to a subsequent image carrier is suppressed.

1 is a schematic perspective view of a charging device according to an embodiment. It is a schematic perspective view which shows the charging member in this embodiment. It is a schematic sectional drawing (AA sectional drawing of FIG. 2) of the charging member in this embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the process cartridge which concerns on this embodiment.

  Hereinafter, embodiments of the present invention will be described in detail.

<Charging device>
The charging device according to the present embodiment includes a roll-shaped charging member and a roll-shaped cleaning member that rotates in contact with the conductive surface layer of the roll-shaped charging member.
Here, the charging member is provided on a conductive support, a conductive elastic layer provided on the outer peripheral surface of the conductive support, and a peripheral surface of the conductive elastic layer, and has a surface free energy of 50 mN. / M to 90 mN / m, and a conductive surface layer.
Further, the cleaning device has a support and a foamed elastic layer provided on the outer peripheral surface of the support and having a foamed cell number of 40 to 75 per 25 mm.

In the charging device according to the present embodiment, as described above, the charging member having the conductive surface layer having a surface free energy of 50 mN / m or more and 90 mN / m or less, and the number of foamed cells of 40 or more and 25 or less per 25 mm. The cleaning member having the foamed elastic layer is configured to bring both the conductive surface layer and the foamed elastic layer into contact with each other.
The reason for this is not clear, but the toner present on the conductive surface layer of the charging member by driven sliding friction between the conductive surface layer of the charging member and the foamed elastic layer of the cleaning member. And foreign substances such as external additives are efficiently removed, and contamination of the conductive surface layer by foreign substances is improved. As a result, streak-like image defects caused by foreign matter on the surface of the charging member can be suppressed.

Hereinafter, the charging device according to the present embodiment will be described with reference to FIG.
Here, FIG. 1 is a schematic perspective view of the charging device according to the present embodiment.

As shown in FIG. 1, in the charging device 12 according to the present embodiment, for example, a charging member 121 and a cleaning member (cleaning member) 122 are arranged in contact with each other with a specific biting amount. Then, both ends in the axial direction of the conductive support (30 in FIGS. 2 and 3) of the charging member 121 and the support 122A of the cleaning member 122 are conductive bearings 123 (conductive bearings) so that the respective members can rotate. ). A power supply 124 is connected to one of the conductive bearings 123.
Each member constituting the charging device 12 will be described in detail below.

[Charging member]
Hereinafter, the charging member 121 will be described with reference to FIGS. 2 and 3.
Here, FIG. 2 is a schematic perspective view showing the charging member in the present embodiment. FIG. 3 is a schematic cross-sectional view of the charging member in the present embodiment. 3 is a cross-sectional view taken along the line AA in FIG.

  2 and 3, the charging member 121 includes, for example, a conductive support 30 (hereinafter referred to as “support 30”) and a conductive elastic provided on the outer peripheral surface of the conductive support 30. Layer 31 (hereinafter referred to as “elastic layer 31”) and conductive surface layer 32 (hereinafter referred to as “surface”) provided on the outer peripheral surface of conductive elastic layer 31 and having a surface free energy of 50 mN / m or more and 90 mN / m or less. A roll member having a layer 32 ”). Note that an adhesive layer (not shown) is provided between the support 30 and the elastic layer 31, for example.

  The charging member 121 in the present embodiment is not limited to the above-described layer configuration, for example, a configuration in which an intermediate layer is provided between the support 30 and the elastic layer 31, or a resistance between the elastic layer 31 and the surface layer 32. The structure which provided the adjustment layer or the transfer prevention layer may be sufficient.

In this specification, the term “conductive” means that the volume resistivity at 20 ° C. is less than 1 × 10 ¹³ Ωcm.

  Hereinafter, the details of the charging member 121 in the present embodiment will be described. In the following description, reference numerals are omitted.

(Support)
The support functions as an electrode and a support member of the charging member. For example, the material is a metal or alloy such as iron (free-cutting steel, etc.), copper, brass, stainless steel, aluminum, nickel; chromium, Iron subjected to a plating treatment with nickel or the like; Examples of the conductive support include a member (for example, a resin or a ceramic member) whose outer peripheral surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like. The support may be a hollow member (cylindrical member) or a non-hollow member.

(Adhesive layer)
Examples of the material for the adhesive layer include known adhesives that are conductive compositions that adhere the support and the elastic layer. Examples of the adhesive include a resin composition containing an electronic conductive agent and a resin composition containing a conductive resin.

(Elastic layer)
The elastic layer includes an elastic material and a conductive agent. The elastic layer may contain other additives as necessary. The elastic layer may also serve as a resistance adjustment layer.

Examples of the elastic material include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, urethane rubber, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide. Examples thereof include copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, ethylene-propylene-diene copolymer rubber, acrylonitrile-butadiene copolymer rubber, natural rubber, and rubbers obtained by mixing these.
Among these elastic materials, silicone rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, and rubbers obtained by mixing these are preferable.
The rubber material may be foamed or non-foamed.

Examples of the conductive agent include electronic conductive materials and ionic conductive materials.
Examples of the electron conductive substance include carbon black such as ketjen black and acetylene black, pyrolytic carbon, graphite, zinc, aluminum, copper, iron, nickel, chromium, titanium and other metals, ZnO-Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O ₃ —SnO ₂ , ZnO—TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , Sb ₂ O ₃ , In ₂ O ₃ , ZnO And known metal oxides such as MgO.
Examples of the ion conductive substance include known salts such as a quaternary ammonium salt, an alkali metal perchlorate, and an alkaline earth metal perchlorate.

  These conductive agents may be used alone or in combination of two or more.

The content of the conductive agent is not particularly limited as long as the desired properties of the elastic layer are obtained.
Specifically, in the case of an electronic conductive material, the content of the conductive agent is preferably 1 part by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the elastic material.
On the other hand, in the case of an ion conductive material, the content of the conductive agent is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the elastic material.

  Examples of other additives in the elastic layer include known additives such as a softener, a plasticizer, a vulcanizing agent, a vulcanization accelerator, an antioxidant, a surfactant, and a coupling agent.

The volume resistivity of the elastic layer is, for example, 10 ³ Ωcm or more and 10 ¹⁴ Ωcm or less, preferably 10 ⁵ Ωcm or more and 10 ¹² Ωcm or less, more preferably 10 ⁷ Ωcm, when the elastic layer also serves as the resistance adjustment layer. It is 10 ¹² Ωcm or less.

The volume resistivity of the elastic layer is a value measured by the following method.
That is, a sheet-like measurement sample is collected from the elastic layer, and a measurement jig (R12702A / B resilience chamber: manufactured by Advantest) and a high resistance measuring device (in accordance with JIS K 6911 (1995)) and a high resistance measuring device ( R8340A digital high resistance / microammeter: manufactured by Advantest), and after applying a voltage adjusted so that the electric field (applied voltage / composition sheet thickness) was 1000 V / cm for 30 seconds, Calculate using the following formula.
Volume resistivity (Ωcm) = (19.63 × applied voltage (V)) / (current value (A) × measured sample thickness (cm))

  The surface roughness Rz of the elastic layer is preferably 20 μm or less, for example, from the viewpoint of suppressing toner or dust from accumulating in the concave portion of the surface layer.

  The surface roughness Rz of the elastic layer is a value measured by the following method. According to JIS B 0601 (1994), the two axial positions of the elastic layer (charging member) in the 20 mm position and the central portion were measured and taken as the average value. As a measuring device, Surfcom 1400 manufactured by Tokyo Seimitsu Co., Ltd. is used. The measurement conditions are cut-off: 0.8 mm, measurement length: 2.4 mm, and traverse speed: 0.3 mm / sec.

  Although the thickness of an elastic layer changes with apparatuses to which a charging member is applied, for example, it is preferably 1 mm or more and 10 mm or less, and preferably 2 mm or more and 5 mm or less.

The thickness of the elastic layer is a value measured by the following method.
That is, the elastic layer (charging member) is cut at the 20 mm position at both ends in the axial direction and at the central portion with a single blade knife, and the cross section of the cut sample is observed at an appropriate magnification according to the thickness of 5 to 50 times. The film thickness is measured and taken as the average value. As a measuring device, a digital microscope VHX-200 manufactured by Keyence Corporation is used.

(Surface layer)
The surface layer is a layer having a surface free energy of 50 mN / m or more and 90 mN / m or less, preferably 55 mN / m or more and 90 mN / m or less.
When the surface free energy of the surface layer is 50 mN / m or more and 90 mN / m or less, an image having excellent graininess can be obtained even if repeated images are formed, and in terms of preventing filming by toner. It is advantageous.

The surface free energy of the surface layer is a value measured by the following method.
That is, pure water, methylene iodide, α-bromonaphthalene, ethylene as reagents with known dipole component, dispersion component and hydrogen bond component of surface free energy in an environment of normal temperature and normal humidity (22 ° C., 55% RH) Glycol was used to measure the contact angle of the surface layer with the contact angle meter CA-X (trade name; manufactured by Kyowa Interface Co., Ltd.), and based on the measurement results, surface free energy analysis software EG-11 (product) Name: Kyowa Interface Co., Ltd.) is used to calculate the surface free energy based on the Fowkes equation. However, the dropping amount of the reagent is 2.5 μL, and the time until the contact angle measurement is 60 seconds after the dropping of the reagent.

The surface free energy of the surface layer can be controlled by a method of adjusting the type of material constituting the surface layer, the mixing ratio, the formation conditions of the surface layer, and the like.
Among these, the surface layer preferably contains a resin, porous resin particles, and silicone oil (hereinafter sometimes referred to as “polysiloxane”) from the viewpoint of easily achieving the surface free energy. .

In the present embodiment, the resin and the content thereof are easy to achieve the above surface free energy, easily form an image having excellent graininess, and prevent image streak defects due to toner filming. 3 parts by mass or more and 25 parts by mass or less of porous resin particles with respect to 100 parts by mass of the resin, and a silicone oil having a content of 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the resin. It is particularly preferable to include it.
When the surface layer 32 is formed by heating the coating film of the coating liquid containing each component, a vortex is generated inside the coating film due to the heating, and as a result, a phenomenon called a Benard cell in which a cell structure appears is generated. When this Benard cell phenomenon occurs, porous resin particles are unevenly distributed at the boundary of the cell structure, and the resistance uniformity of the surface layer is lowered. As a result, the uniform chargeability with respect to the image carrier is also reduced, and the graininess of the image is deteriorated. In particular, when an image is formed at a high process speed, or when a high-quality image with a high resolution is formed, the deterioration of the graininess of the image is noticeable.
For this reason, the occurrence of the Benard cell phenomenon that occurs when the surface layer 32 is formed is suppressed by blending the porous resin particles and the silicone oil in the surface layer 32 in the above amounts. As a result, the dispersibility of the porous resin particles in the surface layer 32 is enhanced, the deterioration of resistance uniformity is suppressed, and an image having excellent granularity can be obtained.

Examples of the resin include acrylic resin, fluorine-modified acrylic resin, silicone-modified acrylic resin, cellulose resin, polyamide resin, copolymer nylon, polyurethane resin, polycarbonate resin, polyester resin, polyimide resin, epoxy resin, silicone resin, and polyvinyl alcohol resin. , Polyvinyl butyral resin, cellulose resin, polyvinyl acetal resin, ethylene tetrafluoroethylene resin, melamine resin, polyethylene resin, polyvinyl resin, polyarylate resin, polythiophene resin. Polyethylene terephthalate resin (PET), fluororesin (polyvinylidene fluoride resin, tetrafluoroethylene resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), etc. ). In addition, the resin is preferably a resin obtained by curing or crosslinking a curable resin with a curing agent or a catalyst.
Here, the copolymer nylon is a copolymer containing any one or more of 610 nylon, 11 nylon, and 12 nylon as polymerized units. The copolymer nylon may contain other polymer units such as 6 nylon and 66 nylon.

  Among these, from the viewpoint of preventing dirt, the resin is preferably a polyvinylidene fluoride resin, a tetrafluoroethylene resin, or a polyamide resin. From the viewpoint of wear resistance of the surface layer and suppression of separation of porous resin particles, the polyamide resin is preferred. Is more preferable.

  Particularly, the polyamide resin is preferably an alkoxymethylated polyamide (alkoxymethylated nylon), more preferably a methoxymethylated polyamide (N-methoxymethyl) from the viewpoint of wear resistance of the surface layer and suppression of separation of the porous resin particles. Nylon).

  The resin preferably has a crosslinked structure from the viewpoint of improving the mechanical strength of the surface layer and suppressing the occurrence of cracks in the surface layer. When the resin has a crosslinked structure, the gel fraction of the surface layer is preferably 50% or more and 100% or less, more preferably 60% or more and 100% or less.

The gel fraction is measured according to JIS K6796.
Specifically, a measurement sample is collected from the surface layer. The mass of the collected measurement sample is measured, and this is defined as the mass before solvent extraction. Next, the measurement sample is immersed in a solvent used for preparing a coating solution for forming a surface layer for 24 hours, and then the solvent is filtered, the remaining residue is filtered, and the weight is measured. This weight is taken as the mass after extraction. Then, the gel fraction is calculated according to the following formula.
Formula: Gel fraction = 100 × (mass after solvent extraction) / (mass before solvent extraction)

  Examples of the porous resin particles include porous particles such as polyamide resin, polyimide resin, polyacrylic acid resin, polymethacrylic resin, polystyrene resin, fluorine resin, and silicone resin.

The number average particle diameter of the porous resin particles is, for example, preferably from 0.1 μm to 30 μm, preferably from 0.5 μm to 20 μm, more preferably from 1 μm to 15 μm.
The number average particle diameter of the porous resin particles is a value measured by the following method. First, porous resin particles are held on a conductive double-sided tape affixed to an SEM sample stage, and this is used as a sample. This sample is observed by SEM (transmission electron microscope). For example, the secondary electron image is observed under the condition that the porous resin particle sample is FE-SEM (JSM-6700F manufactured by JEOL Ltd.) and the acceleration voltage is 5 kV. And let the diameter of the circle | round | yen equal to each projected area of 50 porous resin particles be a particle diameter, and let the average value be a number average particle diameter.

The content of the porous resin particles is preferably 3 parts by mass or more and 25 parts by mass or less, more preferably 5 parts by mass or more and 20 parts by mass or less, and further preferably 10 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the resin. It is.
When the content of the porous resin particles is 3% by mass or more, the surface free energy of the target surface layer becomes easy to be realized, the graininess is improved, and the surface layer is coated with an external additive (filming) ) Becomes difficult to be suppressed. On the other hand, when the content of the porous resin particles is 25 parts by mass or less, the decrease in the resistance uniformity of the surface layer is suppressed, and the graininess is improved.

  Examples of the silicone oil include straight silicones such as dimethyl silicone oil, methyl hydrogen silicone oil, diphenyl silicone oil, methylphenyl silicone oil, and chlorophenyl silicone oil; alkyl-modified silicone oil, aralkyl-modified silicone oil, and polyether-modified silicone oil. And modified silicone oils such as polyester-modified silicone oil, fluoroalkyl-modified silicone oil, amino-modified silicone oil, alkoxy-modified silicone oil, epoxy-modified silicone oil, and carboxyl group-modified silicone oil.

  Among these silicone oils, at least one selected from the group consisting of polyether-modified silicone oils and polyester-modified silicone oils is preferable from the viewpoint of improving the granularity of the image.

  Examples of the polyether-modified silicone oil include a silicone oil in which at least one of the side chain, both ends, and the end of the polysiloxane chain is modified with polyalkylene oxide.

  Examples of the fatty acid ester-modified silicone oil include silicone oil in which at least one of the side chain, both ends, and the end of the polysiloxane chain is modified with polyester.

The content of the silicone oil is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.3 parts by mass or more and 5 parts by mass or less, and further preferably 0.5 parts by mass or more with respect to 100 parts by mass of the resin. 3 parts by mass or less.
When the content of the silicone oil is 0.1 parts by mass or more, the surface free energy of the target surface layer is easily realized, and the occurrence of the Benard cell phenomenon that occurs when the surface layer is formed is suppressed, and the graininess An excellent image can be obtained. On the other hand, when the content of the silicone oil is 10 parts by mass or less, the phenomenon of bleeding of the silicone oil from the surface layer (bleed) is easily suppressed, and the storage characteristics of the charging member are improved.

  In the case where the surface layer contains silicone oil, if the layer existing on the surface of the image carrier (photoconductor) with which the charging member comes into contact contains silicone oil (leveling agent), the silicone oil is removed from the surface layer. Even if a phenomenon of bleeding (bleed) occurs, an image carrier having the same component on the surface is hardly affected. As a result of not being affected by bleeding, the occurrence of image defects due to the image carrier after storage is suppressed. In particular, the silicone oil contained in the surface layer of the charging member and the silicone oil contained in the layer present on the surface of the image carrier are modified at the same modification site (substituents involved in modification). As a result, the above effects are further enhanced. Specifically, it is preferable that both are polyester-modified or polyether-modified.

The surface layer may contain other additives in addition to the components described above.
Other additives include, for example, conductive agents, fillers other than porous particles, curing agents, vulcanizing agents, vulcanization accelerators, antioxidants, surfactants, coupling agents, etc. The well-known additive which can be added to a surface layer is mentioned.

The volume resistivity of the surface layer is, for example, from 10 ³ Ωcm to 10 ¹⁴ Ωcm, preferably from 10 ⁵ Ωcm to 10 ¹² Ωcm, more preferably from 10 ⁷ Ωcm to 10 ¹² Ωcm.

The volume resistivity of the surface layer is a value measured by the following method.
That is, the surface layer is applied to a flat plate of metal such as aluminum or stainless steel or a sheet-like rubber material having a volume resistance of 10 Ωcm or less to obtain a measurement sample. For the measurement sample, according to JIS K 6911 (1995), a measurement jig (R12702A / B resiliency chamber: manufactured by Advantest) and a high resistance measuring device (R8340A digital high resistance / microammeter: manufactured by Advantest) After applying a voltage adjusted so that the electric field (applied voltage / composition sheet thickness) is 1000 V / cm for 30 seconds, it is calculated from the flowing current value using the following equation.
Volume resistivity (Ωcm) = (19.63 × applied voltage (V)) / (current value (A) × measured sample film thickness (cm))

Here, as the resistance of the full device (entire member), a measurement sample is obtained by forming a surface layer only on one side on an elastic layer formed in a sheet shape. For the measurement sample, according to JIS K 6911 (1995), a measurement jig (R12702A / B resiliency chamber: manufactured by Advantest) and a high resistance measuring device (R8340A digital high resistance / microammeter: manufactured by Advantest) The voltage adjusted so that the electric field (applied voltage / thickness of the measurement sample) is 1000 V / cm is applied for 30 seconds, and the current is calculated from the flowing current value using the following formula.
Formula: Volume resistivity (Ωcm) = (19.63 × applied voltage (V)) / (current value (A) × measured sample thickness (cm))

  The surface roughness Rz of the surface layer can suppress streak-like image defects, improve the graininess of the image, and suppress the coating (filming) of the external additive of the toner on the surface layer. From the point, it is preferably 2 μm or more and 10 μm or less, preferably 3 μm or more and 8 μm or less, more preferably 3 μm or more and 6 μm or less.

The surface roughness Rz of the surface layer is a value measured by the following method.
That is, the surface roughness Rz of the surface layer is measured in accordance with JIS B 0601 (1994) at the 20 mm position on both ends in the axial direction of the surface layer (charging member) and at the central portion, and the average value is obtained. As a measuring device, Surfcom 1400 manufactured by Tokyo Seimitsu Co., Ltd. is used. The measurement conditions are cut-off: 0.8 mm, measurement length: 2.4 mm, and traverse speed: 0.3 mm / sec.

  Here, the dynamic ultrafine hardness of the surface of the charging member is, for example, 0.04 or more and 0.5 or less, preferably 0.08 or more and 0.3 or less, from the viewpoint of contamination or cracking.

The dynamic ultra-small hardness (hereinafter also referred to as “DH”) of the surface of the charging member is determined by the test load when the indenter enters the sample at a constant indentation speed (mN / s), P (mN), and indentation depth. When the thickness is D (μm), the hardness is calculated from the following formula. In the following formula, α represents a constant depending on the shape of the indenter.
Formula: DH = α × P / D ²
The measurement of dynamic ultra micro hardness was performed with a dynamic ultra micro hardness meter DUH-W201S (manufactured by Shimadzu Corporation). The dynamic ultrafine hardness is determined by measuring a soft material with a triangular pyramid indenter (apex angle: 115 °, α: 3.8484) pushed into the surface layer of the charging member at a speed of 0.14 mN / s and a test load of 1.0 mN. It is calculated | required by measuring the indentation depth D when making it approach.

  From the viewpoint of resistance stability of the surface layer, the thickness of the surface layer suppresses the movement of the bleed material (the liquid material that oozes out) and the bloom material (the precipitated solid material) from the elastic layer to the surface of the charging member. For example, it is preferably 2 μm or more and 25 μm or less, preferably 3 μm or more and 20 μm or less, more preferably 3 μm or more and 15 μm or less, and further preferably 5 μm or more and 15 μm or less.

The thickness of the surface layer is a value measured by the following method.
That is, the surface layer (charging member) was cut at three positions of 20 mm and both ends in the axial direction with a single-edged knife, the cross section of the cut sample was observed at a magnification of 1000 times, and the film thickness was measured. To do. As a measuring device, a digital microscope VHX-200 manufactured by Keyence Corporation is used.

The surface layer is formed by dispersing each component in a solvent to prepare a coating solution, applying the coating solution on the previously formed elastic layer, and then heating.
Examples of the application method of the coating liquid include blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, curtain coating, flow coating, ring coating, and die coating. And an inkjet coating method.
The solvent used in the coating solution is not particularly limited, and general solvents are used. For example, alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone and methyl ethyl ketone; tetrahydrofuran; diethyl ether and dioxane A solvent such as ethers may be used. In addition to these, various solvents may be used. In order to apply the dip coating method, an alcohol solvent, a ketone solvent, or a mixed solvent thereof may be used.

[Cleaning member (cleaning member)]
Next, the cleaning member (cleaning member) 122 will be described with reference to FIG.
As shown in FIG. 1, the cleaning member 122 is provided on, for example, a conductive support 122A (hereinafter referred to as “support 122A”) and an outer peripheral surface of the conductive support 122A, and the number of foamed cells per 25 mm. 40 to 75 foam elastic layers 122B (hereinafter referred to as “foam elastic layers 122B”).
Hereinafter, the details of the cleaning member 122 according to the present embodiment will be described. In the following description, reference numerals are omitted.

(Support)
The support is a cylindrical or columnar conductive member, and examples of the material thereof include metals such as iron (free-cutting steel, etc.), copper, brass, stainless steel, aluminum, and nickel.
Examples of the support include a member (for example, a resin or a ceramic member) whose outer peripheral surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like.

(Foam elastic layer)
The foamed elastic layer is made of a foam having a porous three-dimensional structure. The foamed elastic layer is a layer having elasticity in which cavities and concavo-convex portions (hereinafter referred to as foamed cells) are present inside and on the surface.
The number of foam cells of the foamed elastic layer is 40 or more and 75 or less per 25 mm, and more preferably 40 or more and 60 or less.
When the number of foamed cells is 40 to 75 per 25 mm, foreign matters such as toner and external additives are efficiently removed by driven sliding friction with the charging member, and streak-like image defects are suppressed.
Here, the “number of foamed cells” in the present specification is the number of cells described in JIS K 6400-1 (2004), and the measuring method is the method described in Appendix 1 of JIS K 6400-1 (2004). Is adopted.

  The foamed elastic layer is made of polyurethane, polyethylene, polyamide, olefin, melamine, polypropylene, NBR (acrylonitrile-butadiene copolymer rubber), EPDM (ethylene-propylene-diene copolymer rubber), natural rubber, styrene butadiene rubber, chloroprene, silicone, A foamable resin material such as nitrile or a rubber material is included.

  Among these foamable resin materials or rubber materials, foreign matters such as toner and external additives are efficiently removed by driven sliding rubbing with the charging member to suppress streak-like image defects, and at the same time, the surface of the charging member In order to make it difficult to damage the cleaning member due to rubbing of the cleaning member, and to make it difficult to cause tearing and breakage over a long period of time, polyurethane is particularly preferably applied.

  The polyurethane is not particularly limited. For example, polyol (for example, polyester polyol, polyether polyol, acrylic polyol, etc.) and isocyanate (2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4, etc.) -Reaction products of diphenylmethane diisocyanate, tolidine diisocyanate, 1,6-hexamethylene diisocyanate, etc.), and reaction products of these chain extenders (for example, 1,4-butanediol, trimethylolpropane, etc.) may be used. .

The foamed elastic layer is formed using a foaming agent, a foam stabilizer, or the like, if necessary, in addition to the foamable resin material or rubber material as described above. In particular, in the case of polyurethane, it is common to foam using a foaming agent, a foam stabilizer or the like.
As the foaming agent, known foaming agents such as water and azo compounds (for example, azodicarbonamide, azobisisobutyronitrile, etc.) are used.
Examples of the foam stabilizer include silicone foam stabilizers (for example, straight silicones such as dimethyl silicone oil, methyl hydrogen silicone oil, diphenyl silicone oil, methylphenyl silicone oil, chlorophenyl silicone oil; alkyl-modified silicone oil, aralkyl-modified silicone). Oil, polyether-modified silicone oil, polyester-modified silicone oil, fluoroalkyl-modified silicone oil, amino-modified silicone oil, alkoxy-modified silicone oil, epoxy-modified silicone oil, modified silicone oil such as carboxyl group-modified silicone oil; A foam stabilizer is used.

  When a silicone compound such as the above silicone foam stabilizer is used for the foamed elastic layer, if the silicone oil is contained in the surface layer of the charging member, the phenomenon of bleeding (bleed) of the silicone compound from the foamed elastic layer may occur. Even if it occurs, charging members containing similar components are less susceptible. As a result of not being influenced by bleeding, the occurrence of image defects due to the charged member after storage is suppressed. In particular, if the silicone oil contained in the surface layer of the charging member and the silicone compound contained in the foamed elastic layer of the cleaning member are modified at the same modification site (substituent involved in modification), The effect like this increases more. Specifically, it is preferable that both are polyester-modified or polyether-modified.

  The hardness of the foamed elastic layer is preferably 100N or more and 500N or less, more preferably 100N or more and 400N or less, and particularly preferably 150N or more and 400N or less.

The foamed elastic layer may have a cylindrical shape formed on the entire outer peripheral surface of the support, or may be formed by spirally winding a strip-shaped foamed elastic member around the outer peripheral surface of the support. .
Further, the foamed elastic layer may be formed by, for example, forming and foaming a mixture of a component constituting the foamed elastic layer and a foaming agent or foam stabilizer that contributes to foaming on the outer peripheral surface of the support. Alternatively, a foam having a through hole provided in advance may be adhered to the outer peripheral surface of the support using an adhesive, and then the outer diameter may be polished.

[Conductive bearing, power supply]
Next, the conductive bearing and the power source in the charging device 12 shown in FIG. 1 will be described.
The conductive bearing 123 is a member that holds the charging member 121 and the cleaning member 122 integrally and rotatably, and also holds an interaxial distance between the members.
The amount of biting between the charging member 121 and the cleaning member 122 is controlled by adjusting the distance between the axes.
The conductive bearing 123 may be of any material and form as long as it is made of a conductive material. For example, a conductive bearing or a conductive sliding bearing is applied.

  The power supply 124 is a device that charges the charging member 121 and the cleaning member 122 to the same polarity by applying a voltage to the conductive bearing 123, and a known high-voltage power supply device is used.

  The charging device according to this embodiment includes a charging member having a conductive surface layer having a surface free energy of 50 mN / m or more and 90 mN / m or less, and a foamed elastic layer having a number of foam cells of 40 to 75 per 25 mm. If it is set as the structure which makes both the electroconductive surface layer and a foaming elastic layer contact, the cleaning member which has this will not be restricted to the said structure.

<Image forming apparatus, process cartridge>
An image forming apparatus according to this embodiment includes an image carrier, a charging device that charges the image carrier, a latent image forming device that forms a latent image on the surface of the charged image carrier, and a surface of the image carrier. A developing device that develops the formed latent image with toner to form a toner image, and a transfer device that transfers the toner image formed on the surface of the image holding member to a recording medium. The charging device according to the present embodiment is applied as the charging device.

On the other hand, the process cartridge according to the present embodiment includes, for example, an image carrier that is detached from the image forming apparatus having the above-described configuration, and a charging device that charges the image carrier. The charging device according to the present embodiment is applied as the charging device.
The process cartridge according to the present embodiment includes, as necessary, a developing device that develops a latent image formed on the surface of the image carrier with toner to form a toner image, and a toner image formed on the surface of the image carrier. At least one selected from the group consisting of a transfer device that transfers the toner to a recording medium and a cleaning device that removes residual toner on the surface of the image carrier after transfer.

Next, the image forming apparatus and the process cartridge according to the present embodiment will be described with reference to FIGS.
Here, FIG. 4 is a schematic configuration diagram illustrating the image forming apparatus according to the present embodiment. FIG. 5 is a schematic configuration diagram showing a process cartridge according to the present embodiment.

  As shown in FIG. 4, the image forming apparatus 101 according to the present embodiment includes an image carrier 10, a charging device 12 that charges the image carrier around the image carrier 10, and an image carrier charged by the charging device 12. An exposure device (latent image forming device) 14 that exposes 10 to form a latent image, a developing device 16 that develops the latent image formed by the exposure device 14 with toner and forms a toner image, and a developing device 16 A transfer device 18 that transfers the toner image to the recording medium P, and a cleaning device 20 that removes residual toner on the surface of the image carrier 10 after the transfer. Further, a fixing device 22 for fixing the toner image transferred to the recording medium P by the transfer device 18 is provided.

  The image forming apparatus 101 according to the present embodiment includes, as the charging device 12, for example, a charging member 121, a cleaning member 122 disposed in contact with the charging member 121, and axial ends of the charging member 121 and the cleaning member 122. The charging device according to the present embodiment, in which a conductive bearing 123 (conductive bearing) that holds each member so as to be rotatable and a power source 124 connected to one of the conductive bearings 123 are disposed. Has been applied.

  On the other hand, in the image forming apparatus 101 of the present embodiment, known configurations are conventionally applied as the respective configurations of the electrophotographic image forming apparatus except for the charging device 12 (the charging member 121 and the cleaning member 122). . Hereinafter, an example of each configuration will be described.

The image carrier 10 is not particularly limited, and a known photoreceptor can be used, but an organic photoreceptor having a so-called function separation type structure in which the photosensitive layer is separated into a charge generation layer and a charge transport layer is preferably used. Is done.
Further, the image carrier 10 whose surface layer is covered with a protective layer having a charge transporting property and having a crosslinked structure is also suitably applied. A photoreceptor composed of a siloxane-based resin, a phenol-based resin, a melamine resin, a guanamine resin, or an acrylic resin as a crosslinking component of the protective layer is also suitably applied.

The image carrier 10 may contain silicone oil as a leveling agent in a layer (charge transport layer or surface layer) existing on the surface thereof.
As described above, the silicone oil used is the same modification site as the silicone oil contained in the foamed elastic layer of the charging member (substituents involved in modification) in order to reduce the influence of bleeding from the charging member 121 as described above. Are preferably selected. Specifically, it is preferable that both are polyester-modified or polyether-modified.

  As the exposure apparatus 14, for example, a laser optical system, an LED (Light Emitting Diode) array, or the like is applied.

  For example, the developing device 16 brings a toner image onto the latent image on the surface of the image carrier 10 by bringing a developer carrier having a developer layer formed on the surface thereof into contact with or close to the image carrier 10. A developing device to be formed. As a developing method of the developing device 16, a developing method using a two-component developer is suitably applied as a known method. Examples of the developing method using the two-component developer include a cascade method and a magnetic brush method.

  As the transfer device 18, for example, either a non-contact transfer method such as corotron or a contact transfer method in which a conductive transfer roll is brought into contact with the image carrier 10 via the recording medium P to transfer a toner image to the recording medium P. May be adapted.

  The cleaning device 20 is, for example, a member that removes toner, paper dust, dust, and the like adhering to the surface by bringing a cleaning blade into direct contact with the surface of the image carrier 10. As the cleaning device 20, a cleaning brush, a cleaning roll, or the like may be applied in addition to the cleaning blade.

  As the fixing device 22, a heat fixing device using a heat roll is suitably applied. The heat fixing device includes, for example, a fixing roller having a heater lamp for heating inside a cylindrical metal core, and a so-called release layer formed on the outer peripheral surface by a heat resistant resin coating layer or a heat resistant rubber coating layer; A pressure roller or a pressure belt that is disposed in contact with the fixing roller at a specific contact pressure and has a heat-resistant elastic body layer formed on the outer peripheral surface of the cylindrical core metal or the surface of the belt-like base material. . The fixing process of the unfixed toner image is performed, for example, by inserting the recording medium P on which the unfixed toner image is transferred between the fixing roller and the pressure roller or the pressure belt, and binding resin in the toner, Fixing by heat melting of additives and the like.

  The image forming apparatus 101 according to the present embodiment is not limited to the above configuration. For example, an intermediate transfer type image forming apparatus using an intermediate transfer member and an image forming unit that forms toner images of each color are arranged in parallel. A so-called tandem image forming apparatus may be used.

  On the other hand, as shown in FIG. 5, the process cartridge according to the present embodiment is provided with the opening 24A for exposure, the opening 24B for static elimination exposure, and the mounting rail 24C in the image forming apparatus shown in FIG. By the housing 24, the image carrier 10, the charging device 12 for charging the image carrier, the developing device 16 for developing the latent image formed by the exposure device 14 with toner and forming a toner image, and after the transfer And a cleaning device 20 that removes residual toner on the surface of the image holding body 10 and is integrally assembled and held. The process cartridge 102 is detachably attached to the image forming apparatus 101 shown in FIG.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited by the following Example. Unless otherwise specified, “part” means “part by mass”.

[Preparation of Photoreceptor 1]
-Formation of undercoat layer-
A cutting aluminum pipe having a diameter of 30 mm was prepared as a support for the photoreceptor.
Next, 100 parts by mass of zinc oxide (average particle size 70 nm: manufactured by Teika: specific surface area value 15 m ² / g) is stirred and mixed with 500 parts by mass of toluene, and a silane coupling agent (KBM603: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 .25 parts by mass was added and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure, baking was performed at 120 ° C. for 3 hours, and a zinc oxide pigment surface-treated with a silane coupling agent was obtained.
60 parts by mass of the zinc oxide pigment subjected to the above surface treatment, 0.6 parts by mass of alizarin, 13.5 parts by mass of a curing agent (blocked isocyanate Sumidur 3175 (manufactured by Sumitomo Bayern Urethane Co., Ltd.)), butyral resin (S Rex BM-1 (manufactured by Sekisui Chemical Co., Ltd.) 38 parts by weight of a solution obtained by dissolving 15 parts by weight in 85 parts by weight of methyl ethyl ketone and 25 parts by weight of methyl ethyl ketone were mixed, and 2 hours in a sand mill using 1 mmφ glass beads Was dispersed to obtain a dispersion.
Dioctyltin dilaurate: 0.005 parts by mass and silicone resin particle Tospearl 145 (manufactured by GE Toshiba Silicone): 4.0 parts by mass were added as catalysts to the resulting dispersion to obtain a coating liquid for forming an undercoat layer. .
This undercoat layer forming coating solution was applied onto the aluminum pipe by adjusting the coating speed so that the film thickness after drying was 23 μm by a dip coating method, and cured by drying at 170 ° C. for 40 minutes, An undercoat layer having a thickness of 23 μm was obtained.

-Formation of charge generation layer-
Next, a photosensitive layer was formed on the undercoat layer.
First, the positions of Bragg angles (2θ ± 0.2 °) of X-ray diffraction spectrum using Cukα as a charge generation material are at least 7.3 °, 16.0 °, 24.9 ° and 28.0 °. 15 parts by mass of a hydroxygallium phthalocyanine having a diffraction peak, 10 parts by mass of vinyl chloride / vinyl acetate copolymer resin (E15 / 45M, manufactured by Wacker) as a binder resin, and 200 parts by mass of n-butyl acetate The resulting mixture was dispersed in a sand mill for 4 hours using 1 mmφ glass beads.
To the obtained dispersion, 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl isobutyl ketone were added and stirred to obtain a coating solution for forming a charge generation layer. This charge generation layer forming coating solution was dip coated on the undercoat layer and dried at 120 ° C. to form a charge generation layer having a thickness of 0.2 μm.

-Formation of charge transport layer-
Next, 1.8 parts by mass of tetrafluoroethylene resin particles (average particle size: average particle size: 0.06 parts by mass of fluorine-based graft polymer GF400 (manufactured by Toa Gosei Co., Ltd.) was dissolved in 4.3 parts by mass of toluene. 0.2 μm) was added, and the mixture was stirred and mixed for 48 hours while maintaining the liquid temperature at 20 ° C. to obtain a tetrafluoroethylene resin particle suspension (liquid A).
Next, 9.8 parts by mass of N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine as a charge transporting substance, bisphenol Z type polycarbonate resin (viscosity average molecular weight: 40,000) 13.0 Part B, 0.26 parts by mass of 2,6-di-t-butyl-4-methylphenol as an antioxidant are mixed and 48.3 parts by mass of tetrahydrofuran and 18.2 parts by mass of toluene are mixed and dissolved. Got.
After the A liquid was added to the B liquid and stirred and mixed, the pressure was increased to 500 kgf / cm ² using a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) equipped with a through-type chamber having a fine flow path. 5 ppm of silicone oil (trade name: Shin-Etsu Silicone KP-340, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the liquid obtained by repeating the dispersion treatment six times, and stirred to obtain a coating liquid for forming a charge transport layer. When the particle size distribution of the resulting coating liquid for forming a charge transport layer was measured with LA920 (manufactured by Horiba Seisakusho), the content ratio of particles of 0.3 μm or more was 96%.
This charge transport layer forming coating solution was applied onto the charge generation layer and dried at 115 ° C. for 40 minutes to form a charge transport layer having a film thickness of 32 μm. Thus, the intended photoreceptor 1 was obtained.

[Preparation of Photoreceptor 2]
The silicone oil (trade name: Shin-Etsu Silicone KP-340, manufactured by Shin-Etsu Chemical Co., Ltd.) added to the coating solution for forming the charge transport layer was replaced with polyether-modified polydimethylsiloxane (trade name: BYK 307, manufactured by BYK). Was prepared in the same manner as the method for manufacturing the photoconductor 1.

[Preparation of Charging Roll A]
-Formation of elastic layer-
A mixture having the composition shown in Table 1 below (mixing ratio in Table 1 is part by mass) is kneaded with an open roll, and a press molding machine is used on the surface of a conductive support made of SUS303 with a diameter of 8 mm through an adhesive layer. Thus, a roll having a diameter of 12.5 mm was formed. Thereafter, a conductive elastic roll having a diameter of 12 mm was obtained by polishing.

-Formation of surface layer-
A conductive elastic roll obtained by diluting 15 parts by mass of a mixture having the composition shown in Table 2 below (the mixing ratio in Table 2 is part by mass) with 85 parts by mass of methanol and dispersing the mixture in a bead mill. After dip-coating on the outer peripheral surface of the elastic layer, it was heated at 140 ° C. for 30 minutes for crosslinking, dried, and a surface layer having a thickness of 15 μm was formed, whereby a charging roll A was obtained.

[Preparation of charging roll B]
Except for forming a surface layer having a film thickness of 10 μm by setting the compounding ratio of the porous polyamide filler to 10 parts by mass and the compounding ratio of the polyether-modified polydimethylsiloxane to 0.5 parts by mass, the same as the production of the charging roll A. Thus, a charging roll B was obtained.

[Preparation of Charging Roll C]
A charging roll C was obtained in the same manner as the preparation of the charging roll B, except that the blending ratio of the polyether-modified polydimethylsiloxane was 1.0 part by mass and a surface layer having a thickness of 10 μm was formed.

[Preparation of charging roll D]
Except for forming a surface layer with a film thickness of 10 μm by setting the compounding ratio of the porous polyamide filler to 5 parts by mass and the compounding ratio of the polyether-modified polydimethylsiloxane to 1.0 part by mass, the same as the production of the charging roll A. Thus, a charging roll D was obtained.

[Preparation of charging roll E]
Charging was carried out in the same manner as the production of the charging roll A, except that the surface mixing layer with a thickness of 3 μm was formed by setting the mixing ratio of the porous polyamide filler to 3 parts by mass and the mixing ratio of the polyether-modified polydimethylsiloxane to 10 parts by mass. Roll E was obtained.

[Preparation of charging roll F]
The charging roll F was prepared in the same manner as the charging roll C except that the polyether-modified polydimethylsiloxane was changed to polyester-modified polydimethylsiloxane (trade name: BYK310 / BYK) and a surface layer having a thickness of 10 μm was formed. Obtained.

[Preparation of charging roll G]
A charging roll G was obtained in the same manner as the charging roll B except that a polyether-modified polydimethylsiloxane was not blended and a surface layer having a thickness of 10 μm was formed.

[Preparation of charging roll H]
A charging roll H was obtained in the same manner as the preparation of the charging roll A except that the mixing ratio of the porous polyamide filler was 26 parts by mass.

[Preparation of Charging Roll I]
Charging was carried out in the same manner as the production of the charging roll A, except that the surface ratio of 3 μm was formed by setting the mixing ratio of the porous polyamide filler to 2 parts by mass and the mixing ratio of the polyether-modified polydimethylsiloxane to 15 parts by mass. Roll I was obtained.

[Preparation of charging roll J]
A charging roll J was obtained in the same manner as the preparation of the charging roll E except that no porous polyamide filler was blended.

[Preparation of cleaning roll a]
A core with 60 foam cells / 25 mm urethane foam (product name: EP-70, manufactured by INOAC Corporation) cut to 15 mm x 15 mm x 350 mm, with a through hole in the center, and an adhesive applied Insert the body (outer diameter: 6 mm, core length: 343 mm: However, the outer diameter φ4 mm of the bearings at both ends in the axial direction of the core body, length 6 mm), and adhere the urethane foam to the core body before The diameter was polished to obtain a cleaning roll a having an elastic layer length of 333 mm in the axial direction and an outer diameter of 10 mm.

[Preparation of cleaning roll b]
A core with a foam cell number of 40/25 mm (product name: RCS, manufactured by INOAC Corporation) cut to a size of 15 mm × 15 mm × 350 mm, a through hole is formed in the center, and an adhesive is applied ( Outer diameter: 6 mm, core length: 343 mm: However, the outer diameter of the bearing part at both ends in the axial direction of the core body is 4 mm and the length is 6 mm, and the urethane foam is bonded to the core body. Polishing was performed to obtain a cleaning roll b having an elastic layer with an axial length of 333 mm and an outer diameter of 10 mm.

[Preparation of cleaning roll c]
Polyether polyol A (trade name: Actol P23, made by Mitsui Chemicals Polyurethane: molecular weight 3000, bifunctional polypropylene glycol) 20 parts by mass, polyether polyol B (trade name: Actol P31, made by Mitsui Chemicals Polyurethane: molecular weight 3000, 3 80 parts by mass of functional polypropylene glycol), 1 part by mass of foam stabilizer (trade name: trade name: BYK310 / BYK company: polyester-modified silicone oil), 0.5 part by mass of catalyst (trade name: Kaulizer No31, manufactured by Kao Corporation) And 6 parts by mass of a blowing agent (water) are mixed, and further, isocyanate (trade name: Cosmonate T-80, made by Mitsui Chemicals Polyurethane: tolylene diisocyanate (hereinafter sometimes referred to as “TDI”)) 66.2 Mass parts were mixed and foamed. Furthermore, this foam was heated at 80 ° C. for 1 hour, allowed to stand at room temperature, and then cooled to prepare a urethane foam having 70 foam cells / 25 mm.
Insert this urethane foam into the core (outer diameter: 6 mm, core length: 343 mm; however, the outer diameter φ4 mm and the length of 6 mm of the bearings at both ends in the axial direction of the core) and apply urethane. After the foam was bonded to the core, the outer diameter was polished to obtain a cleaning roll c having an elastic layer with an axial length of 333 mm and an outer diameter of φ10 mm.

[Preparation of cleaning roll d]
A core with 38 foam cells / 25 mm urethane foam (product name: RR-26, manufactured by INOAC Corporation) cut to 15 mm x 15 mm x 350 mm, with a through hole in the center and coated with an adhesive Insert the body (outer diameter: 6 mm, core length: 343 mm: However, the outer diameter φ4 mm of the bearings at both ends in the axial direction of the core body, length 6 mm), and adhere the urethane foam to the core body before The diameter was polished to obtain a cleaning roll d having an elastic layer with an axial length of 333 mm and an outer diameter of φ10 mm.

[Preparation of cleaning roll e]
A urethane foam having 76 foam cells / 25 mm was produced in the same manner as the production of the cleaning roll c except that the amount of the catalyst used for the production of the cleaning roll c was 0.7 parts.
This urethane foam is cut into a size of 15 mm × 15 mm × 350 mm, a through hole is made in the center, and an adhesive is applied to the core (outer diameter: 6 mm, core length: 343 mm: provided that the core shaft The outer diameter of the bearings at both ends in the direction is 4 mm and the length is 6 mm), the urethane foam is bonded to the core, the outer diameter is polished, and the elastic layer has an axial length of 333 mm and an outer diameter of 10 mm. Roll e was obtained.

[Measurement of surface free energy and surface roughness Rz]
With respect to the charging rolls A to J obtained as described above, the surface free energy and the surface roughness Rz were measured by the method described above.
Table 3 shows the measurement results.

[Examples 1-7, Comparative Examples 1-6]
In the combination shown in Table 3, the photoconductor, charging roll, and cleaning roll are incorporated into a drum cartridge for 700 Digital Color Press manufactured by Fuji Xerox Co., Ltd., and this drum cartridge is used as a remodeling machine for 700 Digital Color Press manufactured by Fuji Xerox Co., Ltd. Installed.
With this modified machine, a continuous print test of 100,000 sheets was performed, and the image quality and the charging roll were evaluated as follows.

(Evaluation of image quality)
Using the above-mentioned modified machine, output 50,000 sheets of each color image density 5% A28 paper (Fuji Xerox, C2 paper) in 28 ° C 85% RH environment, then in 10 ° C 15% RH environment 50,000 sheets were output, and after a total of 100,000 sheets were output, an entire halftone image with an image density of 30% was output, and the presence or absence of occurrence of streaky density unevenness in the process direction was evaluated.
The evaluation criteria are as follows. The results are shown in Table 3. In practice, G1 and G2 are acceptable.
-Evaluation criteria-
G1: No streaking G2: An extremely slight streak that does not cause any problem in image quality is confirmed G3: Between G2 and G4 G4: An unacceptable streak in image quality is confirmed

(Evaluation of charging roll dirt)
After the evaluation was completed, the charging roll was taken out from the apparatus, and the contamination state was evaluated visually with the following criteria. The results are shown in Table 3. In practice, G1 and G2 are acceptable.
-Evaluation criteria-
G1: Very slight and slight contamination was confirmed.
G2: Slight streak-like contamination was confirmed.
G3: Severe streak-like contamination was confirmed.
G4: Contamination including contamination other than enormous streaks was confirmed.

(Evaluation after storage)
In the combination shown in Table 3, the photoconductor, the charging roll, and the cleaning roll are assembled in a 700 Digital Color Press drum cartridge manufactured by Fuji Xerox Co., Ltd., and left in a 45 ° C., 95% environment for one month. The cartridge was mounted on a remodeling machine of 700 Digital Color Press manufactured by Fuji Xerox.
Using the modified machine, five full-tone images with an image density of 30% were output on A3 paper (Fuji Xerox Co., C2 paper) in an environment of 22 ° C. and 55% RH. Based on the following criteria, the presence or absence of streaks corresponding to the charging roll pitch and the photoreceptor pitch in the halftone image was evaluated as a difference in image density.
As the evaluated image, an image having the largest difference in image density among the five images was used. The results are shown in Table 3. In practice, G1 and G2 are acceptable.
-Evaluation criteria-
G1: No streaking G2: An extremely slight streak that does not cause any problem in image quality is confirmed G3: Between G2 and G3 G4: An unacceptable streak in image quality is confirmed

From the above results, it can be seen that streaky density unevenness is suppressed in this example as compared with the comparative example.
Further, in this example, it can be seen that the evaluation of the contamination of the charging roll and the evaluation of the streaks in the image after storage are also good.
In particular, this Example 7 in which the silicone oil contained in the charge transport layer of the photoreceptor and the silicone oil contained in the surface layer of the charging roll is of the same modified type is particularly suitable for the pitch of the photoreceptor in the image after storage. It can be seen that in the evaluation of streaks, good results are shown.
In Examples 1 to 7 in which the silicone oil contained in the surface layer of the charging roll and the silicone foam stabilizer contained in the foamed elastic layer of the cleaning roll are of the same modified type, It can be seen that good results are shown in the evaluation of the pitch streaks.

DESCRIPTION OF SYMBOLS 10 Image carrier, 12 Charging device, 14 Exposure device, 16 Developing device, 18 Transfer device, 20 Cleaning device, 22 Fixing device, 24 Housing, 24A Opening, 24B Opening, 24C Mounting rail, 30 Base material, 31 Conductive elastic layer, 32 conductive surface layer, 101 image forming apparatus, 102 process cartridge, 121 charging member, 122 cleaning member, 122A support, 122B foamed elastic layer, 123 conductive bearing, 124 power supply

Claims (10)

A conductive support, a conductive elastic layer provided on the outer peripheral surface of the conductive support, and provided on the outer peripheral surface of the conductive elastic layer, the surface free energy is 50 mN / m or more and 90 mN / m or less A roll-shaped charging member having a conductive surface layer, and
A support and a foamed elastic layer provided on the outer peripheral surface of the support and having a number of foam cells of 40 to 75 per 25 mm, and contact the conductive surface layer of the charging member. And a roll-shaped cleaning member that rotates.   The charging device according to claim 1, wherein the conductive surface layer in the charging member includes porous resin particles and silicone oil.   The charging device according to claim 2, wherein the silicone oil is at least one selected from the group consisting of a polyether-modified silicone oil and a polyester-modified silicone oil.   4. The charging device according to claim 2, wherein the foamed elastic layer in the cleaning member contains a silicone compound having the same modification site as the silicone oil included in the conductive surface layer in the charging member.   The charging device according to claim 1, wherein a surface roughness Rz of the conductive surface layer in the charging member is 2.0 μm or more and 10.0 μm or less.   The charging device according to claim 1, wherein the foamed elastic layer in the cleaning member is a urethane foam layer. An image carrier,
The charging device according to any one of claims 1 to 6, comprising a charging member and a cleaning member, and charging the image holding member by bringing the charging member into contact with the image holding member.
And a process cartridge that is detachably attached to the image forming apparatus. Claim conductive surface layer in the charging member comprises a silicone oil, a layer on the surface of the image carrier is, containing a silicone oil having the same modified cite silicone oil with the previous Kishirube conductive surface layer 8. The process cartridge according to 7. An image carrier,
The charging device according to any one of claims 1 to 6, comprising a charging member and a cleaning member, and charging the image holding member by bringing the charging member into contact with the image holding member.
A latent image forming apparatus for forming a latent image on the surface of the charged image carrier;
A developing device for developing a latent image formed on the surface of the image carrier with toner to form a toner image;
A transfer device for transferring the toner image formed on the surface of the image carrier to a recording medium;
An image forming apparatus comprising: Claim conductive surface layer in the charging member comprises a silicone oil, a layer on the surface of the image carrier is, containing a silicone oil having the same modified cite silicone oil with the previous Kishirube conductive surface layer The image forming apparatus according to 9.