JP2012220576A - Charging member, process cartridge and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging member in an electrophotographic device, the member suppressing image failure, which is referred as a C-set (compression set) image, occurring when a charging member and a photoreceptor are left to stand in contact with each other for a long period of time.SOLUTION: A charging member 5 includes a conductive substrate 1 and an elastic layer 2. The elastic layer 2 contains a diene rubber, electronic conductive particles dispersed in the rubber, ionic conductive particles dispersed in the rubber, and a polyalkylene oxide having a weight average molecular weight of 3000 to 10000; wherein the polyalkylene oxide includes polyethylene oxide in the molecule thereof.

Description

  The present invention relates to a charging member, and more particularly to a charging member for applying a voltage to charge the surface of an electrophotographic photosensitive member as a member to be charged to a predetermined potential. The present invention also relates to a process cartridge and an electrophotographic apparatus using a charging member.

An electrophotographic apparatus adopting an electrophotographic system mainly includes an electrophotographic photosensitive member, a charging device, an exposure device, a developing device, a transfer device, and a fixing device.
The charging device applies a voltage (a voltage of only a DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage) to a charging member placed in contact with or close to the surface of the electrophotographic photosensitive member to thereby apply the surface of the electrophotographic photosensitive member. Many charging methods are used. From the viewpoint of stably charging and reducing the generation of ozone, a contact-type charging method is preferably used.

In the case of the contact charging method, a roller-shaped charging member (hereinafter referred to as “charging roller”) is preferably used. The charging roller is placed in contact with the electrophotographic photosensitive member by a pressing force of a spring or the like and is driven to rotate.
When left in the above state for a long period of time, the charging roller is distorted at the contact portion with the electrophotographic photosensitive member, and so-called compression set (hereinafter referred to as “C set”) is generated, which is deformed semipermanently. The amount of distortion becomes more conspicuous when the left environment is high temperature and high humidity.

Such a proposal for improving the technical problem of C set is described in Patent Document 1.
In recent years, there has been a demand for higher speed, higher image quality, and higher durability for electrophotographic apparatuses, and improvement of the C set is desired.
When the electrophotographic photosensitive member is charged using a charging member in which C set is generated, a portion where C set is generated (hereinafter referred to as “C set portion”) is uniform when passing through the discharge region. A small discharge gap cannot be maintained. This causes a difference in charging ability between the C set portion and the non-C set portion. As a result, image density unevenness (hereinafter referred to as “C set image”) such as a horizontal black stripe and / or a horizontal white stripe in the longitudinal direction occurs at a position corresponding to the C set portion. Further, the C set image tends to be more easily generated when the voltage applied to the charging member is a DC voltage only.

JP 2000-265008 A Japanese Patent Laid-Open No. 10-154416 Japanese Patent Laid-Open No. 2006-039394

  The present invention provides a charging member that suppresses the generation of a streak-like image called a C-set image that occurs when the charging member and the photosensitive member are left in contact with each other for a long period of time in a charging member of an electrophotographic apparatus. is there.

  That is, the charging member of the present invention is a charging member having a conductive substrate and an elastic layer, and the elastic layer is dispersed in a diene rubber, electronic conductive particles dispersed in the rubber, and in the rubber. And ionic conductive particles containing polyalkylene oxide, and polyalkylene oxide having a weight average molecular weight of 3000 to 10,000, wherein the polyalkylene oxide contains polyethylene oxide in the molecule.

  According to the present invention, it is possible to suppress a change in charging ability at the C set portion of the charging member that occurs after being left in contact with the electrophotographic photosensitive member for a long time. Thereby, generation | occurrence | production of C set image can be suppressed.

It is sectional drawing of the charging roller which concerns on this invention. It is explanatory drawing of the electrical resistance value measuring method of a charging roller. 1 is a cross-sectional view of an electrophotographic apparatus according to the present invention. It is sectional drawing of the process cartridge which concerns on this invention. FIG. 2 is a schematic diagram illustrating a contact state between a charging roller and an electrophotographic photosensitive member. The schematic of the crosshead extrusion apparatus which uses a charging roller for manufacture is shown.

The charging member of the present invention has a conductive base and an elastic layer, and is used for charging a member to be charged.
The elastic layer is composed of diene rubber, electron conductive particles dispersed in the diene rubber, ion conductive particles containing polyalkylene oxide, and polyalkylene oxide containing polyethylene oxide having a weight average molecular weight of 3000 to 10,000. It is characterized by including in.

The elastic layer has a molecular weight of 3000 to 10,000, in which electronic conductive particles and ion conductive particles are dispersed in the diene rubber, and has a low affinity with the diene rubber and a high affinity with the ion conductive particles. Contains large liquid polyalkylene oxide. With such a configuration, the liquid polyalkylene oxide having ionic conductivity is unevenly distributed in the vicinity of the interface between the matrix phase and the ionic conductive particles, and ionic conductivity can be obtained between the ionic conductive particles. Thus, by using an elastic layer in which an ion conductive path is formed in the matrix phase made of electronic conductive rubber, the change in conductivity when stress is applied to the charging member is reduced, and the C set image It is assumed that it has become possible to suppress the occurrence of
Patent Document 2 proposes that the elastic layer contain hydrin rubber particles and the like.
Patent Document 3 describes an example of a proposal that a liquid material containing polyalkylene oxide is contained as a plasticizer for rubber. However, in the system in which the hydrin rubber particles and the liquid material containing polyalkylene oxide are dispersed, it is considered that the effect of suppressing the C set image of the charging member of the present invention is hardly exhibited.

<Charging member>
The charging member is not limited to a roller shape but may be a flat plate shape or a belt shape. FIG. 1 shows a roller-shaped charging member. Moreover, you may have a surface layer on an elastic layer as needed. FIG. 1A shows a roller-shaped charging member 5 having a two-layer structure of a conductive substrate 1 and an elastic layer 2, and FIG. 1B shows 3 of a conductive substrate 1, an elastic layer 2, and a surface layer 3. A roller-shaped charging member 5 having a layer structure is shown. These drawings are schematic sectional views of the charging member of the present invention. Hereinafter, the roller shape shown in FIG. 1, that is, the charging roller will be described in detail.

The conductive substrate and the elastic layer, or the layers sequentially laminated (for example, the elastic layer 2 and the surface layer 3) may be bonded via an adhesive. In this case, the adhesive is preferably conductive. In order to make it conductive, the adhesive may have a known conductive agent.
Examples of the binder of the adhesive include thermosetting resins and thermoplastic resins, and known ones such as urethane, acrylic, polyester, polyether, and epoxy can be used.

As a conductive agent for imparting conductivity to the adhesive, it can be appropriately selected from conductive agents described in detail later, and can be used alone or in combination of two or more.
The charging roller of the present invention usually has an electric resistance of 1 × 10 ² Ω or more and 1 × 10 ¹⁰ Ω or less in an environment of 23 ° C./50% RH in order to improve the charging of the photoreceptor. More preferably.

  As an example, FIG. 4 shows a method for measuring the electrical resistance of the charging roller. Both ends of the conductive substrate 1 are brought into contact with a columnar metal 32 having the same curvature as that of the photoconductor by bearings 33a and 33b under load. In this state, the cylindrical metal 32 is rotated by a motor (not shown), and a DC voltage of −200 V is applied from the stabilized power supply 34 while the charging roller 5 that is in contact with the rotation is driven to rotate. The current flowing at this time is measured by an ammeter 35, and the resistance of the charging roller is calculated. As will be described later, the load was 4.9 N for each metal cylinder, the diameter of the metal cylinder was 30 mm, and the rotation of the metal cylinder was a peripheral speed of 45 mm / sec.

  From the viewpoint of making the longitudinal nip width uniform with respect to the photoreceptor, the charging roller preferably has a shape in which the central portion in the longitudinal direction is the thickest and becomes thinner toward both ends in the longitudinal direction, so-called crown shape. The crown amount is preferably such that the difference between the outer diameter at the center and the outer diameter at a position 90 mm away from the center is not less than 30 μm and not more than 200 μm.

[Conductive substrate]
The conductive substrate is conductive and has a function of supporting an elastic layer or the like provided thereon. Examples of the material include metals such as iron, copper, stainless steel, aluminum, nickel, and alloys thereof.

[Elastic layer]
The elastic layer contains diene rubber containing electron conductive particles, ion conductive particles containing polyalkylene oxide, and polyalkylene oxide containing polyethylene oxide having a weight average molecular weight of 3000 to 10,000.

<Diene rubber>
The diene rubber is a rubber containing a diene typified by butadiene as one of polymerization components. Typical diene rubbers include BR (butadiene rubber), SBR (styrene butadiene rubber), EPDM (ethylene propylene diene rubber), IR (isoprene rubber), and NBR (acrylonitrile butadiene rubber). These rubbers are mainly composed of diene having a low polarity. For this reason, it has low affinity with the material containing polyalkylene oxide, and liquid polyalkylene oxide is unevenly distributed at the interface with the ion conductive particles dispersed in the diene rubber, and the ionic conductivity in the matrix phase is reduced. Can be improved. In addition, by using a diene rubber with low water absorption, it is possible to reduce the water absorption of the ion conductive particles, and to obtain the effect of suppressing the change in conductivity when left in contact for a long time in a high temperature and high humidity environment. .

<Electronic conductive particles>
Examples of the electronic conductive particles include the following. Examples thereof include metal-based fine particles and fibers such as aluminum, palladium, iron, copper, and silver, and metal oxides such as titanium oxide, tin oxide, and zinc oxide that have been subjected to conductive treatment. Moreover, the composite particle which surface-treated by the electrolytic treatment, the spray coating, and the mixed shaking is mentioned on the surface of the metal-based fine particles, fibers and metal oxides described above. Examples thereof include carbon powders such as furnace black, thermal black, acetylene black, ketjen black, PAN (polyacrylonitrile) -based carbon, and pitch-based carbon.
Examples of furnace black include the following.

These electronic conductive particles can be used alone or in combination of two or more.
Further, the electron conductive particles are preferably carbon black. Carbon black has high hydrophobicity and a structure structure, and can further improve the hydrophobicity and reinforcing property of the matrix phase. Further, the average particle diameter is more preferably 0.01 μm to 0.9 μm, and still more preferably 0.01 μm to 0.5 μm. Within this range, the volume resistivity of the matrix phase can be easily controlled.

The addition amount of the electronic conductive particles is in the range of 2 to 80 parts by mass, preferably 20 to 60 parts by mass with respect to 100 parts by mass of the binder (diene rubber). When the addition amount is less than 20 parts by mass, the effect of reinforcement is reduced. Moreover, when the addition amount exceeds 60 parts by mass, the resistance of the matrix phase in the elastic layer is low, and it is difficult to obtain the effect of ion conductivity due to the ion conductive particles and the liquid polyalkylene oxide.
<Ion conductive particles>
The ion conductive particles are particles obtained by crosslinking a resin or rubber containing polyalkylene oxide as a structure with a crosslinking agent, or particles obtained by self-crosslinking by applying energy such as electron beam irradiation. By using ionic conductive particles having alkylene oxide, liquid polyalkylene oxide having a weight-average molecular weight that is contained in rubber separately from the ionic conductive particles is prevented from being taken into the ionic conductive particles. be able to. As a result, the liquid polyalkylene oxide having a defined weight average molecular weight is unevenly distributed in the vicinity of the surface of the ionic conductive particles, so that the ionic conductivity of the elastic layer is improved and the change in conductivity when stress is applied to the elastic layer. It is thought to suppress.

  The ion conductive particles are required to have a structure containing polyalkylene oxide. Furthermore, it is preferable to include polyethylene oxide because it exhibits good ionic conductivity. As a preferable range of the content of polyethylene oxide, polyethylene oxide is 50 to 95 mol% with respect to 100 mol% of polyalkylene oxide. A more preferable range is 70 to 90 mol%. By setting it as the said range, the ionic conductivity of an elastic layer improves more and the suppression effect of a C set image increases. The higher the mol% content of polyethylene oxide, the better the ionic conductivity, but when it exceeds 90 mol%, the crystallinity due to polyethylene oxide increases, and the ionic conductivity tends to decrease. Specifically, epichlorohydrin / ethylene oxide binary copolymer rubber, epichlorohydrin / ethylene oxide / allyl glycidyl ether terpolymer rubber, ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer rubber with a crosslinking agent. What formed into the particle | grains the crosslinked rubber obtained by bridge | crosslinking is used suitably.

As the cross-linking agent, a known cross-linking agent such as sulfur-based, organic peroxide-based, or polythiol-based can be used.
A preferable range of the particle diameter of the ion conductive particles is 1 μm to 100 μm. More preferably, it is 5 micrometers-50 micrometers. By setting it in the above range, resistance irregularity of the elastic layer is small and conduction by ionic conductive particles is easily formed, so that the ionic conductivity of the elastic layer is further improved and the effect of suppressing the C set image is enhanced.

(Measuring method of average particle diameter of ion conductive particles)
Here, as the average particle diameter of the ion conductive particles, a measurement value obtained by measuring the powdered ion conductive particles using a Coulter counter multisizer or the like can be adopted.
For example, 0.1 to 5 ml of a surfactant (alkylbenzene sulfonate) is added to 100 to 150 ml of the electrolyte solution, and 2 to 20 mg of a measurement sample (ion conductive particles) is added thereto. The electrolyte solution in which the sample is suspended is dispersed with an ultrasonic disperser for 1 to 3 minutes, and an aperture adjusted to an appropriate ionic conductive particle size such as 17 μm or 100 μm with a Coulter counter multisizer is used as the reference volume. Measure particle size distribution of 3 to 64 μm.
The mass average particle diameter measured under these conditions is determined by computer processing.

  Moreover, the measuring method of the particle diameter of the ion conductive particle in the state already contained in the elastic layer can also be easily obtained by observing the cross section of the layer with a microscope or the like. First, the cross section of the elastic layer is observed with a TEM (transmission electron microscope), and the projected area of the ion conductive particles is obtained from the cross-sectional image data of the ion conductive particles, and then the diameter of a circle having an area equal to this area. Is the particle diameter of the ion conductive particles. Similarly, the diameter of a circle having an area equal to this area was obtained from the cross-sectional projected area of another ion conductive particle, and the arithmetic average of the diameters of these circles was defined as the average particle diameter.

  In the present invention, an arbitrary point of the elastic layer is cut out with a focused ion beam “FB-2000C” (manufactured by Hitachi, Ltd.) by 20 nm over 500 μm, and a cross-sectional image thereof is taken. Then, a three-dimensional image is calculated by combining images obtained by photographing the same ion conductive particles. The projected area of the ion conductive particles is obtained from the three-dimensional image of the ion conductive particles, and then the diameter of a circle having an area equal to this area is set as the particle diameter of the resin particles. Similarly, the diameter of a circle having an area equal to this area was obtained from the cross-sectional projected area of another ion conductive particle, and the arithmetic average of the diameters of these circles was defined as the average particle diameter.

Such an operation is performed for 10 ion conductive particles in the field of view. Then, the same measurement is performed for 10 points in the longitudinal direction of the charging member, and an average value of a total of 100 obtained is calculated.
A preferable range of the addition amount of the ion conductive particles is 50 parts by mass to 250 parts by mass with respect to 100 parts by mass of the diene rubber. A more preferable range is 80 to 200 parts by mass. By setting it as the said range, since the change of the electroconductivity by the use environment of an elastic layer is small and ionic electroconductivity can be improved, the inhibitory effect of a C set image increases.

  The ion conductive particles may contain an ion conductive agent for the purpose of improving ion conductivity. Examples of the ion conductive agent include the following. Inorganic ionic substances such as lithium perchlorate, sodium perchlorate, calcium perchlorate, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, trioctylpropylammonium Cationic surfactants such as bromide, modified aliphatic dimethylethylammonium ethosulphate, zwitterionic surfactants such as lauryl betaine, stearyl betaine, dimethylalkyl lauryl betaine, tetraethylammonium perchlorate, tetrabutylammonium perchlorate, Quaternary ammonium salts such as trimethyloctadecyl ammonium perchlorate, trifluoro Organic acid lithium salts of lithium methanesulfonate or the like. These can be used alone or in combination of two or more. Among ionic conductive agents, quaternary ammonium perchlorate is particularly preferably used because of its resistance to environmental changes.

In order to adjust the workability and mechanical properties of the elastic layer, those having a known filler added thereto can be used as the ion conductive particles.
For example, carbon black may be added for the purpose of imparting reinforcement. When carbon black is added, it is preferable to use carbon black having low conductivity such as MT, FT, GPF, and SRF carbon black. The carbon black is preferably added in the range of 0.5 to 10 parts by mass with respect to 100 parts by mass of the rubber.

Moreover, you may add inorganic fillers, such as various calcium carbonate, a talc, clay, a silica, as a filler.
As a method for producing ion conductive particles, first, the above materials are kneaded in a kneader such as a closed mixer or a biaxial kneader, and then crosslinked to produce a crosslinked rubber. The produced crosslinked rubber can be produced by freezing and pulverizing into particles.

  The polyalkylene oxide has a weight average molecular weight of 3000 to 10,000. This polyalkylene oxide is a polyalkylene oxide that is unevenly distributed in the vicinity of the interface of the ion conductive particles dispersed in the diene rubber, and is not a polyalkylene oxide contained in the ion conductive particles. By setting the weight average molecular weight within the above range, it can be unevenly distributed in the vicinity of the interface between the matrix phase and the ion conductive particles, so that ion conductivity by the ion conductive particles and the polyalkylene oxide can be obtained, and the ion conductivity of the elastic layer can be increased. Can be improved. When the weight average molecular weight is less than 3000, the fluidity is large, and therefore, when compressive strain is applied to the elastic layer for a long period of time, the polyalkylene oxide diffuses into the elastic layer due to the compressive stress, and the ionic conductivity tends to decrease. . Further, when the weight average molecular weight exceeds 10,000, it becomes rubbery or resinous, so it is difficult to exist at the interface between the diene rubber and the ion conductive particles, and is present in the rubber separately from the ion conductive particles. Conductive paths are difficult to form. In addition, the polyalkylene oxide contains polyethylene oxide, and the ethylene oxide is preferably contained in an amount of 30 mol% or more, more preferably 70 to 90 mol% with respect to 100 mol% of the polyalkylene oxide. preferable. By setting it as the said range, the ionic conductivity of a polyalkylene oxide can improve and the ionic conductivity of an elastic layer can be improved more.

Specific examples of the polyalkylene oxide of the present invention include polyether polyol.
As the polyether polyol, a conventionally known material may be used, and the polyether polyol can be produced by addition polymerization of an alkylene oxide to an active hydrogen compound in the presence of a potassium hydroxide catalyst. While alkylene oxide is continuously fed into an autoclave charged with a potassium hydroxide catalyst and an active hydrogen compound, the reaction is carried out at a reaction temperature of 105 to 150 ° C. and a reaction pressure of 480 to 600 kPa until a predetermined molecular weight is obtained. Next, after neutralizing potassium hydroxide in the polyoxyalkylene polyol with an inorganic acid, the potassium salt deposited by dehydration and drying can be filtered to produce the desired polyether polyol.

(Method for measuring weight average molecular weight of polyalkylene oxide)
A calibration curve was prepared using standard polystyrene having a known molecular weight (molecular weight distribution = 1) using gel permeation chromatography (GPC) and chloroform as a developing solvent. Based on this calibration curve, it was calculated from the retention time of GPC.
In addition, a compounding agent of a plasticizer, a filler, a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, a scorch preventing agent, a dispersing agent and a release agent can be added to the elastic layer as necessary.

  The elastic layer can be formed by a known method such as extrusion molding, injection molding or compression molding after mixing the raw material rubber composition of the elastic body with a closed mixer. The elastic layer may be produced by directly molding an elastic body on a conductive substrate provided with an adhesive layer. Alternatively, a conductive elastic body previously formed into a tube shape may be formed on the conductive substrate. Note that the surface may be polished and the shape may be adjusted after the elastic layer is formed.

The hardness of the elastic layer is preferably 70 ° or less, more preferably 60 ° or less in terms of micro hardness (MD-1 type). When the micro hardness (MD-1 type) exceeds 70 °, the nip width between the charging roller and the photosensitive member becomes small.
In addition, "micro hardness (MD-1 type)" is the hardness measured using Asker micro rubber hardness meter MD-1 type (trade name, manufactured by Kobunshi Keiki Co., Ltd.). Specifically, the hardness meter is a value measured in a 10 N peak hold mode with respect to a charging roller left in an environment of normal temperature and normal humidity (23 ° C./55% RH) for 12 hours or more.

The volume resistivity of the surface layer is preferably 1 × 10 ² Ω · cm or more and 1 × 10 ¹⁰ Ω · cm or less in a 23 ° C./50% RH environment in order to set the electric resistance of the charging member to the above. .
The volume resistivity of the elastic layer is a volume resistivity measurement sample obtained by molding all materials used for the elastic layer into a sheet with a thickness of 2 mm and depositing metal on both sides to form electrodes and guard electrodes. obtain. A voltage of 200 V is applied to the measurement sample using a microammeter (trade name: ADVANTEST R8340A ULTRA HIGH RESISTANCE METER, manufactured by Advantest Co., Ltd.). Then, the current after 30 seconds is measured and calculated from the thickness and the electrode area.
The elastic layer may be subjected to a surface treatment. Examples of the surface treatment include a surface processing treatment using UV or electron beam, and a surface modification treatment for adhering and / or impregnating a compound or the like on the surface.

[Surface layer]
(Binder resin)
As the binder used for the surface layer, a known binder can be employed. For example, resin, natural rubber, a vulcanized product thereof, synthetic rubber and the like can be mentioned.
As the resin, a resin such as a thermosetting resin or a thermoplastic resin can be used. Of these, fluorine resin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, and the like are more preferable.

Synthetic rubbers include ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer rubber (SBR), silicone rubber, urethane rubber, isoprene rubber (IR), butyl rubber, acrylonitrile-butadiene copolymer rubber (NBR). Chloroprene rubber (CR), acrylic rubber, epichlorohydrin rubber and the like can be used.
The volume resistivity of the surface layer is preferably 1 × 10 ³ Ω · cm or more and 1 × 10 ¹³ Ω · cm or less in a 23 ° C./50% RH environment in order to set the electric resistance of the charging member to the above. .

The volume resistivity of the surface layer is determined as follows. First, the surface layer is peeled off from the roller state and cut into strips of about 5 mm × 5 mm. Metal is vapor-deposited on both surfaces to produce an electrode and a guard electrode, and a measurement sample is obtained. Alternatively, it is applied on an aluminum sheet to form a surface layer coating film, and a metal for vapor deposition is deposited on the coating film surface to obtain a measurement sample. About the obtained sample for a measurement, it can measure similarly to the volume resistivity measuring method of the said elastic layer.
The volume resistivity of the surface layer can be adjusted by a conductive agent such as an ionic conductive agent or an electronic conductive agent.

  Examples of the ion conductive agent include the following. Inorganic ionic substances such as lithium perchlorate, sodium perchlorate, calcium perchlorate, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, trioctylpropylammonium Cationic surfactants such as bromide, modified aliphatic dimethylethylammonium ethosulphate, zwitterionic surfactants such as lauryl betaine, stearyl betaine, dimethylalkyl lauryl betaine, tetraethylammonium perchlorate, tetrabutylammonium perchlorate, Quaternary ammonium salts such as trimethyloctadecyl ammonium perchlorate, trifluoro Organic acid lithium salts of lithium methanesulfonate or the like. These can be used alone or in combination of two or more.

  Examples of the electronic conductive agent include the following. Metal fine particles and fibers such as aluminum, palladium, iron, copper, and silver, and metal oxides such as titanium oxide, tin oxide, and zinc oxide that have been subjected to a conductive treatment. Composite particles obtained by surface-treating the surfaces of the metal-based fine particles, fibers and metal oxides described above by electrolytic treatment, spray coating, and mixed shaking. Carbon powder such as furnace black, thermal black, acetylene black, ketjen black, PAN (polyacrylonitrile) carbon, pitch carbon.

Examples of furnace black include the following. SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, I-ISAF-HS, HAF-HS, HAF, HAF-LS, T-HS, T-NS, MAF, FEF, GPF, SRF-HS- HM, SRF-LM, ECF, FEF-HS. Thermal black includes FT and MT.
Moreover, these electrically conductive agents can be used individually or in combination of 2 or more types.

The conductive agent preferably has an average particle size of 0.01 μm to 0.9 μm, and more preferably 0.01 μm to 0.5 μm. Within this range, the volume resistivity of the matrix layer can be easily controlled.
The amount of these conductive agents added to the surface layer is suitably in the range of 2 to 80 parts by weight, preferably 20 to 60 parts by weight with respect to 100 parts by weight of the binder.

  The surface of the conductive agent may be treated. As the surface treatment agent, organosilicon compounds such as alkoxysilanes, fluoroalkylsilanes, polysiloxanes, etc., various silane, titanate, aluminate and zirconate coupling agents, oligomers or polymer compounds can be used. These may be used alone or in combination of two or more. Preferred are organosilicon compounds such as alkoxysilanes and polysiloxanes, silane-based, titanate-based, aluminate-based or zirconate-based coupling agents, and more preferable are organosilicon compounds.

The surface layer may be subjected to a surface treatment. Examples of the surface treatment include a surface processing treatment using UV or electron beam, and a surface modification treatment for adhering and / or impregnating a compound or the like on the surface.
The surface layer of the present invention preferably has a thickness of 0.1 μm or more and 100 μm or less. More preferably, they are 1 micrometer or more and 50 micrometers or less.

(Formation of surface layer)
The surface layer can be formed by a coating method such as electrostatic spray coating or dipping coating. Or it can form by adhere | attaching or coat | covering the sheet-shaped or tube-shaped layer beforehand formed into the film thickness of predetermined thickness. Alternatively, a method of curing and molding the material into a predetermined shape in the mold can also be used. Among these, it is preferable to apply a paint by a coating method to form a coating film.
When a layer is formed by a coating method, the solvent used in the coating solution may be any solvent that can dissolve the binder resin. Specifically, alcohols such as methanol, ethanol, isopropanol, ketones such as acetone, methyl ethyl ketone, cyclohexanone, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, Examples thereof include ethers such as tetrahydrofuran, dioxane and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, and aromatic compounds such as xylene, ligroin, chlorobenzene and dichlorobenzene. These solvents are appropriately selected according to the binder resin used.
As a method for dispersing the binder, particles and the like in the coating solution, known solution dispersing means such as a ball mill, a sand mill, a paint shaker, a dyno mill, and a pearl mill can be used.

[Electrophotographic equipment]
FIG. 5 shows a schematic configuration of an example of an electrophotographic apparatus provided with the charging member of the present invention.
The electrophotographic apparatus includes a photosensitive member, a charging device that charges the photosensitive member, a latent image forming device that performs exposure, a developing device that develops the toner image, a transfer device that transfers to a transfer material, and a cleaning that collects the transfer toner on the photosensitive member. And a fixing device for fixing the toner image.
The photoreceptor 4 is a rotary drum type having a photosensitive layer on a conductive substrate. The photoreceptor is driven to rotate in the direction of the arrow at a predetermined peripheral speed (process speed).

The charging device includes a contact-type charging roller 5 that is placed in contact with the photosensitive member 4 by being brought into contact with the photosensitive member 4 with a predetermined pressing force. The charging roller 5 is driven rotation that rotates according to the rotation of the photosensitive member, and charges the photosensitive member to a predetermined potential by applying a predetermined voltage from the charging power source 19.
As a latent image forming apparatus (not shown) that forms an electrostatic latent image on the photoreceptor 4, for example, an exposure apparatus such as a laser beam scanner is used. An electrostatic latent image is formed by irradiating the uniformly charged photoreceptor with exposure light 11 corresponding to image information.

The developing device has a developing roller 6 disposed close to or in contact with the photoreceptor 4. The toner electrostatically processed to the same polarity as the photosensitive member charge polarity is developed by reversal development to visualize and develop the electrostatic latent image into a toner image.
The transfer device has a contact-type transfer roller 8. The toner image is transferred from the photoreceptor to a transfer material 7 such as plain paper (the transfer material is conveyed by a paper feed system having a conveying member).

The cleaning device has a blade-type cleaning member 10 and a recovery container, and after transferring, mechanically scrapes and recovers transfer residual toner remaining on the photosensitive member.
Here, it is possible to omit the cleaning device by adopting a development simultaneous cleaning system in which the transfer device collects the transfer residual toner.
The fixing device 9 is constituted by a heated roller or the like, and after fixing the transferred toner image on the transfer material 7, discharges the transfer material 7 out of the apparatus.

[Process cartridge]
It is also possible to use a process cartridge (FIG. 6) in which a photoreceptor, a charging device, a developing device, a cleaning device, etc. are integrated and designed to be detachable from the electrophotographic apparatus.
That is, the charging member is a process cartridge that is at least integrated with the member to be charged and is configured to be detachable from the main body of the electrophotographic apparatus, and the charging member is the above-described charging member.
The electrophotographic apparatus includes at least a process cartridge, an exposure device, and a fixing device, and the process cartridge is the process cartridge described above.

Hereinafter, the present invention will be described in more detail with reference to specific examples, but the technical scope of the present invention is not limited thereto.
[Production of ion conductive particles containing polyalkylene oxide]
(Production Example 1) Ion conductive particles 1
The components shown in Table 1 were kneaded for 15 minutes in a closed mixer adjusted to 80 ° C.

これに、表２に示す成分を、２５℃に冷却した二本ロール機にて１０分間混練し、原料ゴム組成物を得た。

The components shown in Table 2 were kneaded for 10 minutes in a two-roll machine cooled to 25 ° C. to obtain a raw rubber composition.

原料ゴム組成物を、熱プレスにて１０ＭＰａの圧力下、１６０℃で３０分間加硫を行って１００ｍｍ×１５０ｍｍ×２ｍｍのゴムシートを得た。ゴムシートの体積抵抗率は、以下に述べる方法で測定した。得られたゴムシートの両面に金属を蒸着して電極とガード電極とを形成し、２３℃、５０％の環境下に２４時間放置した。その後、前記環境下において、微小電流計（商品名：ＡＤＶＡＮＴＥＳＴ Ｒ８３４０Ａ ＵＬＴＲＡ ＨＩＧＨ ＲＥＳＩＳＴＡＮＣＥ ＭＥＴＥＲ、（株）アドバンテスト製）を用いて、２００Ｖの直流電圧を印加して３０秒後の電流を測定した。得られた電流値とゴムシートの厚さと電極面積とから、体積抵抗率を算出した。
ゴムシートを液体窒素にて冷却粉砕及び分級し、平均粒子径２０μｍのイオン導電粒子を得た。物性を表８に示す。

The raw rubber composition was vulcanized at 160 ° C. for 30 minutes under a pressure of 10 MPa with a hot press to obtain a rubber sheet of 100 mm × 150 mm × 2 mm. The volume resistivity of the rubber sheet was measured by the method described below. A metal was vapor-deposited on both surfaces of the obtained rubber sheet to form an electrode and a guard electrode, and left for 24 hours in an environment of 23 ° C. and 50%. Thereafter, under the above environment, a direct current of 200 V was applied and a current after 30 seconds was measured using a microammeter (trade name: ADVANTEST R8340A ULTRA HIGH RESISTANCE METER, manufactured by Advantest Co., Ltd.). The volume resistivity was calculated from the obtained current value, the thickness of the rubber sheet, and the electrode area.
The rubber sheet was cooled and pulverized and classified with liquid nitrogen to obtain ion conductive particles having an average particle diameter of 20 μm. Table 8 shows the physical properties.

(Production Examples 2-7) Ion conductive particles 2-7
A rubber sheet was produced in the same manner as in Production Example 1. Cooling and pulverization and classification were performed to obtain ion conductive particles 2 to 7 having an average particle diameter different from that of the ion conductive particles 1. Table 8 shows the physical properties.
(Production Example 8) Ion conductive particles 8
In Production Example 1, ion conductive particles 8 were obtained in the same manner as Production Example 1 except that the raw rubber composition shown in Table 3 was used. Table 8 shows the physical properties.

(Production Examples 9-12) Ion conductive particles 9-12
A rubber sheet was produced in the same manner as in Production Example 8. Cooling pulverization and classification were performed to obtain ion conductive particles 9 to 12 having an average particle diameter different from that of the ion conductive particles 8. Table 8 shows the physical properties.
(Production Example 13) Ion conductive particles 13
In Production Example 1, ion conductive particles 13 were obtained in the same manner as in Production Example 1 except that the raw rubber composition shown in Table 4 was used. Table 8 shows the physical properties.

(Production Examples 14-17) Ion conductive particles 14-17
A rubber sheet was produced in the same manner as in Production Example 13. Cooling and pulverization and classification were performed to obtain ion conductive particles 14 to 17 having an average particle diameter different from that of the ion conductive particles 13. Table 8 shows the physical properties.
(Production Example 18) Ion conductive particles 18
In Production Example 1, ion conductive particles 18 were obtained in the same manner as Production Example 1 except that the raw rubber composition shown in Table 5 was used. Table 8 shows the physical properties.

(Production Examples 19-22) Ion conductive particles 19-22
A rubber sheet was produced in the same manner as in Production Example 18. Cooling pulverization and classification were performed to obtain ion conductive particles 19 to 22 having an average particle diameter different from that of the ion conductive particles 18. Table 8 shows the physical properties.
(Production Example 23) Ion conductive particles 23
In Production Example 1, ion conductive particles 23 were obtained in the same manner as Production Example 1 except that the raw rubber composition shown in Table 6 was used. Table 8 shows the physical properties.

(Production Examples 24-27) Ion conductive particles 24-27
A rubber sheet was produced in the same manner as in Production Example 23. Cooling pulverization and classification were performed to obtain ion conductive particles 24 to 27 having an average particle diameter different from that of the ion conductive particles 23. Table 8 shows the physical properties.
(Production Example 28) Ion conductive particles 28
In Production Example 1, ion conductive particles 28 were obtained in the same manner as Production Example 1 except that the raw rubber composition shown in Table 7 was used. Table 8 shows the physical properties.

Example 1
[Production of Charging Roller 1]
(Production of elastic layer)
Add ingredients shown in Table 9 to 100 parts by mass of styrene butadiene rubber (bound styrene content 23.5%, Mooney viscosity 35) and knead for 15 minutes in a closed mixer adjusted to 80 ° C. to prepare a raw material compound did.

To this, 2 parts by weight of sulfur as a vulcanizing agent, 1 part by weight of dibenzothiazyl sulfide (DM) and 1 part by weight of tetramethylthiuram monosulfide (TS) as vulcanization accelerators were added and cooled to 25 ° C. The raw rubber composition was obtained by kneading for 10 minutes in a roll machine.
A thermosetting adhesive (trade name: METALOC U-20, manufactured by Toyo Chemical Laboratory Co., Ltd.) is applied to a stainless steel rod having a diameter of 6 mm and a length of 252 mm, and left standing in a hot air oven at 180 ° C. for 30 minutes. Thus, a conductive substrate was obtained.

Subsequently, by using an extrusion molding apparatus including the cross head 37 shown in FIG. 8, the raw rubber composition is coated coaxially and cylindrically with the conductive substrate 1 as the central axis, and the raw rubber composition layer is formed. A charging member preform 39 having an outer diameter of φ9.2 mm was obtained.
The crosshead 37 is a device that is generally used for coating electric wires and wires, and is used by being attached to a rubber discharge portion of a cylinder of the extruder 38.
This was heated in a hot air oven at 160 ° C. for 60 minutes, and then the end portion of the elastic layer was removed to obtain an elastic layer having a length of 226.5 mm. Next, the outer peripheral surface of the elastic layer was polished using a plunge cut type cylindrical polishing machine, and the outer diameter of the elastic layer was adjusted to φ8.5 mm.

(Preparation of surface layer)
Methyl isobutyl ketone was added to the caprolactone-modified acrylic polyol solution to adjust the solid content to 16% by mass. The components shown in Table 10 were added to 714.3 parts by mass of this solution (100 parts by mass of acrylic polyol solid content) to prepare a mixed solution of urethane resin.

At this time, the blocked isocyanate mixture was such that the amount of isocyanate was “NCO / OH = 1.0”.
(* 1) Modified dimethyl silicone oil “SH28PA” (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.)
(* 2) 7: 3 mixture of each butanone oxime block of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI)

  200 g of the above mixed solution was placed in a glass bottle having an inner volume of 450 mL together with 200 g of glass beads having an average particle diameter of 0.8 mm as a medium, and dispersed for 48 hours using a paint shaker disperser. After the dispersion, the glass beads were removed to obtain a surface layer coating solution. Using the surface layer coating solution, dipping coating was performed once on the elastic roller. Here, the dipping coating is as follows. The immersion time was 9 seconds, the dipping coating lifting speed was an initial speed of 20 mm / s and a final speed of 2 mm / s, and the speed was changed linearly with respect to the time. After the coating, it was air-dried at room temperature for 30 minutes or more, and dried with a hot air circulating dryer at 80 ° C. for 1 hour and further at 160 ° C. for 1 hour to obtain a charging roller 1 having a surface layer formed on the elastic layer. The thickness of the surface layer was 10 μm.

[Measurement of resistance of charging roller]
The resistance of the prepared charging roller was measured.
The measurement method of electrical resistance is shown. As shown in FIG. 4A, the shaft 1 at both ends of the charging roller is brought into contact with the cylindrical metal 32 having the same curvature as that of the photosensitive member by the bearings 33a and 33b to which the load is applied. Let Next, as shown in FIG. 4B, the cylindrical metal 32 is rotated by a motor (not shown), and a DC voltage of −200 V is applied from the stabilizing power source 34 while the roller is driven and rotated while being in contact with the cylindrical metal 32. The current flowing through the charging roller was measured by an ammeter 35. The resistance of the charging roller was calculated based on the measured value. In the present invention, a force of 4.9 N was applied to both ends of the shaft to contact a metal cylinder having a diameter of 30 mm, and the metal cylinder was rotated at a peripheral speed of 45 mm / second.
In addition, when the charging roller of Example 1 was left in an N / N (normal temperature and normal humidity: 23 ° C./55% RH) environment for 24 hours or more and then the electrical resistance was measured, it was 1.6 × 10 ⁵ Ω. .

[Image evaluation]
A color laser jet printer (LBP5400) manufactured by Canon Inc., which is an electrophotographic apparatus having the configuration shown in FIG. 5, was used by modifying the recording medium output speed to 200 mm / second (A4 vertical output). The resolution of the image is 600 dpi, and the primary charging output is a DC voltage of −1100V.
The process cartridge for the printer (for black) was used as a process cartridge having the configuration shown in FIG.

  The charging roller was removed from the process cartridge, and the manufactured charging roller 1 was set. The charging roller was brought into contact with the photosensitive member with a pressing force of a spring of 4.9 N at one end and a total of 9.8 N at both ends (FIG. 7). The process cartridge was left in a 40 ° C., 95% RH environment for 1 month, and then removed from the environment. After that, the taken out process cartridge was conditioned for 24 hours in an N / N environment (23 ° C., 50% RH) and an L / L environment (15 ° C., 10% RH), and then incorporated into an electrophotographic apparatus to obtain an image. Evaluation was performed.

A halftone image (an image in which a straight line having a width of 1 dot and an interval of 2 dots is drawn in the rotation direction and the longitudinal direction of the photoreceptor) was output and evaluated. Table 12 shows the evaluation results of the output image. In Table 12, rank A does not generate a black streak-like image. In rank B, only a slight black streak-like image is generated in a part of the halftone image. In rank C, a slight black streak-like image can be confirmed with the charging roller pitch in a part of the halftone image, but the image has no practical problem. Rank D is an image in which a black streak-like image is conspicuous in the halftone image, and deterioration in image quality is recognized.
With respect to the charging roller 1 of this example, a black streak-like image was not generated in both the N / N environment and the L / L environment, and a good image was obtained.

(Examples 2 to 63)
In Example 1, charging rollers 2 to 63 were produced in the same manner as Example 1 except that the type of polyalkylene oxide was changed as shown in Tables 11 to 12. The charging rollers 2 to 63 were evaluated in the same manner as in Example 1. The results are shown in Tables 13-14.

(Comparative Example 1)
In Example 1, the charging roller 64 was manufactured in the same manner as in Example 1 except that the changes were made as shown in Table 12. The charging roller 64 was evaluated in the same manner as in Example 1. The results are shown in Table 15.

(Comparative Example 2)
In Example 1, it changed as shown in Table 12, and changed polyalkylene oxide into the polyethyleneglycol whose weight average molecular weight is 600. Except for these changes, a charging roller 65 was produced in the same manner as in Example 1. The charging roller 65 was evaluated in the same manner as in Example 1. The results are shown in Table 15.

(Comparative Example 3)
In Example 1, it changed as shown in Table 12, and changed polyalkylene oxide into the unbridged epichlorohydrin rubber (Epichlorohydrin / ethylene oxide binary copolymer 50 mol% / 50 mol% Mooney viscosity 65). A charging roller 66 was produced in the same manner as in Example 1 except for these changes. The charging roller 66 was evaluated in the same manner as in Example 1. The results are shown in Table 15.

(Comparative Example 4)
In Comparative Example 2, a charging roller 67 was produced in the same manner as Comparative Example 2 except that no ion conductive particles were added. The charging roller 67 was evaluated in the same manner as in Example 1. The results are shown in Table 15.

(Comparative Example 5)
In Comparative Example 4, the rubber type was changed to hydrin rubber (epichlorohydrin / ethylene oxide / allyl glycidyl ether terpolymer 48 mol% / 48 mol% / 4 mol% Mooney viscosity 65). Except for this change, the charging roller 68 was produced in the same manner as in Comparative Example 4. The charging roller 68 was evaluated in the same manner as in Example 1. The results are shown in Table 15.

SBR JSR1507
(Bound styrene content 23.5%, diene content 66.5%, Mooney viscosity 35)
EPDM Esplen 505
(Ethylene / propylene / ethylidene norbornene copolymer diene content 10%, Mooney viscosity 47)
BR JSR BR01
(Mooney viscosity 45)
NBR N230SV
(Bound acrylonitrile amount 33.5%, diene amount 66.5%, Mooney viscosity 32)

Polyalkylene oxide 1
(EO / PO addition type polyether polyol, weight average molecular weight 5000, EO ratio 70 mol%)
Polyalkylene oxide 2
(EO / PO addition type polyether polyol, weight average molecular weight 4000, EO ratio 50 mol%)
Polyalkylene oxide 3
(EO / PO addition type polyether polyol, weight average molecular weight 3000, EO ratio 70 mol%)
Polyalkylene oxide 4
(EO / PO addition type polyether polyol, weight average molecular weight 3000, EO ratio 30 mol%)
Polyalkylene oxide 5
(EO / PO addition type polyether polyol, weight average molecular weight 10,000, EO ratio 80 mol%)

Polyethylene glycol (weight average molecular weight 600)
Uncrosslinked hydrin rubber (epichlorohydrin / ethylene oxide / allyl glycidyl ether terpolymer 50 mol% / 50 mol%, Mooney viscosity 65)
Carbon black 1
(Primary average particle size 28nm, DBP oil absorption 87cm3 / 100g)
Carbon black 2
(Primary average particle size 30 nm, DBP oil absorption 350 cm3 / 100 g)
Conductive zinc oxide (aluminum-doped zinc oxide primary particle size 150nm)

  As shown in the results of Tables 13 to 15 above, the charging roller of the present invention can suppress the generation of black streak-like images (C set images) and provide a good image, and is incorporated in an electrophotographic apparatus and a process cartridge. Is preferable.

DESCRIPTION OF SYMBOLS 1 Conductive base | substrate 2 Elastic layer 3 Surface layer 4 Electrophotographic photoreceptor 5 Charging member (charging roller)
6 Developing roller 7 Print media 8 Transfer roller 9 Fixing unit 10 Cleaning blade 11 Exposure 12 Pre-charging exposure device 13 Elastic regulating blade 14 Toner supply rollers 18, 19, 20 Power supply 30 Toner seal 32 Cylindrical metal 33 Bearing 34 Power supply 35 Ammeter 36 Feed roll 37 Cross head 38 Extruder 39 Charged member preform

Claims (6)

A charging member having a conductive substrate and an elastic layer,
The elastic layer is
Diene rubber,
Electronically conductive particles dispersed in the rubber,
Ion conductive particles containing polyalkylene oxide dispersed in the rubber,
and,
Including a polyalkylene oxide having a weight average molecular weight of 3000 to 10,000,
The charging member, wherein the polyalkylene oxide contains polyethylene oxide in the molecule.   The charging member according to claim 1, wherein the ion conductive particles contain polyethylene oxide in a proportion of 70 mol% or more and 90 mol% or less with respect to 100 mol% of the polyalkylene oxide.   The charging member according to claim 1, wherein the elastic layer includes the ion conductive particles in a ratio of 80 parts by mass or more and 200 parts by mass or less with respect to the diene rubber. The electronic conductive particles are carbon black;
The charging member according to any one of claims 1 to 3, wherein the elastic layer includes the electronic conductive particles in a ratio of 20 parts by mass or more and 60 parts by mass or less with respect to the diene rubber.   5. A process cartridge comprising the charging member according to claim 1 and a photosensitive member, wherein the process cartridge is detachably attached to a main body of the electrophotographic apparatus. An electrophotographic apparatus comprising the charging member according to claim 1 and a photoconductor.

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