JP2010060609A - Charging roller and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems (deterioration in energizing, compression set) for attaining a longer service life in a charging roller under a large current energizing condition (for example, ≥0.2 mA for DC and at the same time ≥2 mA for AC) in a high temperature and high humidity environment (for example, 30°C and relative humidity of 80%). <P>SOLUTION: The charging roller with a conductive layer on a conductive supporting body has the conductive layer formed by styrene-butadiene rubber (SBR) in which the amount of combined styrene is ≥40 mass% and ≤60 mass% and at the same time includes carbon black with the average particle diameter of ≥150 nm and ≤500 nm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charging roller mainly used in OA equipment such as an electrophotographic apparatus and a copying machine, and an electrophotographic apparatus having the charging roller.

  2. Description of the Related Art Conventionally, in an electrophotographic apparatus, an image forming unit is installed inside a main body, and an image is formed through cleaning, charging, latent image, development, transfer, and fixing processes. The image forming unit includes a photosensitive drum that is an electrophotographic photosensitive member, and includes a cleaning unit, a charging unit, a latent image forming unit, a developing unit, and a transfer unit. The image on the photosensitive drum formed by the image forming unit is transferred to the recording material at the transfer unit, and after being transported to the fixing unit, heated and pressed by the fixing unit to be fixed on the recording material. Is output.

  Next, the charging, latent image formation, development, and transfer processes in the cleaning, charging, latent image, development, transfer, and fixing processes will be described.

  In the charging unit, the charging member performs primary charging with a predetermined polarity on the surface of the photosensitive drum so that the potential is uniform. Next, by receiving exposure of target image information, an electrostatic latent image corresponding to the target image is formed on the surface of the photosensitive drum. This electrostatic latent image is visualized as a toner image from the developing member in the developing unit. The visualized toner image is transferred from the surface of the photosensitive drum to the recording material by the transfer member at the transfer portion. The transferred unfixed toner image is conveyed to a fixing unit, fixed by the fixing unit, and output as a recorded image.

  There are a corona charging method and a roller charging method as charging methods used in image forming apparatuses such as electrophotographic apparatuses and electrostatic recording apparatuses. The corona charging method is a charging method in which a voltage is applied to a corona wire to form a charged product, the surface of the photosensitive drum is charged with the charged product, and a latent image is formed. On the other hand, in the roller charging method, the surface of the photosensitive drum is charged by discharge by bringing the charging roller into contact with or close to the photosensitive drum (the distance between the roller drums is close to several tens of μm but not in contact), and a latent image is formed. Charging method.

  The roller charging method has an extremely small amount of ozone and discharge products generated compared to the corona charging method. Therefore, by using roller charging, it is possible to reduce the space for attaching the ozone filter, and to reduce image blurring caused by discharge products.

  The roller charging method is divided into AC + DC charging in which alternating current (AC) is superimposed on direct current (DC), and DC charging only in DC. DC charging is a suitable technology to achieve downsizing and low cost, but the charging bias area that keeps the photoreceptor drum potential constant is narrow, roller resistance circumferential unevenness and minute resistance unevenness due to dirt, roller nonuniformity It is technically difficult to achieve image quality stability such as non-uniform charging due to characteristics. If this is a high-speed and long-life office copying machine with a printing speed of 50 sheets or more and a maintenance interval of 250,000 sheets or more, it is more difficult to maintain image quality with DC charging, and AC + DC charging is preferred.

  A problem in roller charging by AC + DC charging is energization deterioration. The deterioration of energization is a phenomenon in which when a current is passed through a roller, the roller resistance changes and a desired drum potential cannot be applied. In general, energization deterioration is a phenomenon in which the drum potential decreases due to an increase in roller resistance. As for the energization deterioration, techniques related to Patent Documents 1 to 3 have been reported.

  In recent years, an electrophotographic apparatus is required to have high image quality and a long life. As an approach from an electrophotographic photosensitive member to satisfy high image quality, a method of increasing the electrostatic capacitance of the electrophotographic photosensitive member by thinning the electrophotographic photosensitive member to make the contrast of the latent image clearer, Examples thereof include an electrophotographic photoreceptor corresponding to a laser having a wavelength (particularly 380 to 500 nm). Further, as an approach from the electrophotographic photosensitive member for satisfying the long life, a method using an amorphous silicon photosensitive member, a method of providing a surface protective layer for protecting the photosensitive layer, and the like can be mentioned.

  When a roller charging method is employed in an electrophotographic process using an amorphous silicon photoreceptor or a thin film photoreceptor, a large current is required for charging because the electrostatic capacity of the photoreceptor is large. Accordingly, a large current also flows through the charging roller, and the charging roller becomes highly resistive (energized deterioration). In particular, in a high temperature and high humidity environment (for example, 30 ° C. and relative humidity 80%), the energization deterioration becomes more severe. Further, in an electrophotographic process using an amorphous silicon photoconductor or a thin film photoconductor, it is possible to design an electrophotographic system having a very high durability and a long life. However, in the roller charging method, there is a problem that permanent deformation is caused by contact with the cleaning member of the charging roller or the photosensitive member, and good image formation cannot be achieved over a long period of time.

  Patent Documents 1 to 3 disclose an invention related to a charging roller having a small resistance change before and after energization. However, the energization conditions described in these patent documents are low current, and an amorphous silicon photoreceptor or a thin film photoreceptor is used. It is not assumed to be used in the electrophotographic system provided.

Patent Documents 4 to 6 disclose inventions that deal with deterioration of energization of the charging roller. Specifically, an ion conductive agent is used for the charging roller (Patent Document 4), or a polymer having an SP value intermediate between NBR and EPDM is mixed as a connection between the NBR and EPDM polymer alloys constituting the conductive roller. (Patent Document 5) and the like are described. Further, as a countermeasure against compression set of the charging roller, a function of rotating the charging roller while being in contact with the photoconductor in a state where the photoconductor is stopped (Patent Document 6), or in order to improve the compression set Describes how to prescribe the charging roller (Patent Document 7).
Japanese Patent No. 3018906 Japanese Patent No. 3633808 JP 2000-003086 A JP 11-295963 A Japanese Patent No. 3424485 JP 2005-234439 A JP 2002-072628 A

  As in Patent Document 4, in a charging roller using an ionic conductive agent, in a high-temperature and high-humidity environment under a large current energizing condition, the ionic conductive agent oozes to the surface, causing a rise in resistance and toner contamination on the drum. There is a possibility of becoming. By covering the surface protective layer, the ionic conductive agent can be prevented from exuding, but it may be difficult to suppress the deterioration of energization under a large current energizing condition with a known surface protective layer. Further, as in Patent Document 5, in the case of a conductive roller using a polymer alloy-based material, when the polymer to be mixed is hydrophilic, there is a possibility that deterioration of energization in a high-temperature and high-humidity environment is worsened. In addition, since polymer alloys have a sea-island structure, the dispersion state of carbon black tends to change with respect to subtle changes in the sea-island structure, especially for conductive rollers of the electron conduction type (for example, carbon black). And deterioration of energization is not preferable. Moreover, even if a structural function of the apparatus system is provided as in Patent Document 6, the compression set of the charging roller is often caused by the prescription of the charging roller, which may not be a solution. In addition, if the charging roller is rotated while being in contact with the photoconductor while the photoconductor is stopped, the wear of the photosensitive layer and the surface protective layer of the photoconductor is promoted, and it is impossible to maintain a long-life electrophotographic system. There is sex. In addition, as described in Patent Document 7, even if the amount of deformation of the conductive rubber layer, which is a main factor of compression set, is suppressed and the compression set is improved, the deterioration of energization in a high-temperature and high-humidity environment under a large current supply condition. It is necessary to balance the improvement.

  The present invention achieves a long life of a charging roller in a high-temperature and high-humidity environment (for example, 30 ° C. and a relative humidity of 80%) under a large current conduction condition (for example, a direct current of 0.2 mA or more and an alternating current of 2 mA or more). The object is to solve the problems (deterioration of energization, compression set).

  Means for solving the present invention includes a charging roller having a conductive layer on a conductive support, wherein the conductive layer is formed of styrene butadiene rubber (SBR) having an amount of bonded styrene of 40% by mass or more and 60% by mass or less, and an average. A charging roller comprising carbon black having a particle size of 150 nm to 500 nm.

  The first electrophotographic apparatus according to the present invention includes at least an electrophotographic photosensitive member having a photoconductive layer composed of an amorphous material having a silicon atom as a base material, and a surface of the photosensitive member by a proximity or contact charging method. An electronic device comprising: a charging means for charging the toner; a latent image forming means for exposing the image to form a latent image; a developing means for forming a toner image on the photosensitive member; and a transfer means for transferring the toner image to the transfer body. An electrophotographic apparatus using the charging roller of the present invention as a charging means in a photographic apparatus.

  The second electrophotographic apparatus according to the present invention includes at least an organic electrophotographic photosensitive member having a surface protective layer and a photosensitive layer thickness of 20 μm or less, and charging for charging the surface of the photosensitive member by proximity or contact charging. An electrophotographic apparatus comprising: a means; a latent image forming means that exposes an image to form a latent image; a developing means that forms a toner image on a photoconductor; and a transfer means that transfers a toner image to a transfer object. An electrophotographic apparatus using the charging roller of the present invention as charging means.

  Charging that contains the material satisfying the SBR microstructure (bound styrene content, vinyl content), carbon black average particle size, carbon black addition amount, and SP value and T2HH within the range defined by the present invention. Roller is a means to solve the deterioration of energization and compression set, which are issues related to long life in high-temperature and high-humidity environments in electrophotographic processes (amorphous silicon photoreceptor, thin-film OPC mounting process) that require high-current energization conditions. It can be.

  As a configuration of a charging roller for achieving a long life in a high-temperature and high-humidity environment under a large current energizing condition of the present invention, in the charging roller having a conductive layer on a conductive support, the conductive layer has a bound styrene content of 40. It is desirable that the charging roller be made of styrene butadiene rubber (SBR) having a mass percentage of not less than 60 mass% and containing carbon black having an average particle size of not less than 150 nm and not more than 500 nm.

  The reason why SBR having an amount of bound styrene of 40% by mass or more and 60% by mass or less is desirable is a range in which a chemically stable phenyl group and a highly reactive diene group are balanced against current deterioration in a high temperature and high humidity environment. Because. When the amount of bound styrene is less than 40% by mass, the deterioration of energization in a high temperature and high humidity environment deteriorates. The reason for this is that highly reactive diene group residues are increased, and high resistance of the base polymer due to discharge deterioration is promoted. When the amount of bound styrene exceeds 60% by mass, the elastic modulus of the conductive layer is lost when the number of butadiene groups decreases. For example, when the styrene group is in contact with the photosensitive drum for a long period of time, compression contact distortion occurs at the contact portion. It causes a defect. On the other hand, when the amount of bound styrene exceeds 60% by mass, a rapid improvement tendency of the deterioration of energization is not recognized, resulting in a negative effect.

  It is even more desirable that the vinyl content of SBR is 10% by mass or more and 30% by mass or less. When the amount of vinyl in SBR is less than 10% by mass, many unreacted diene group residues that remain unreacted after vulcanization remain in the main chain, and discharge deterioration proceeds mainly in the main chain of the base polymer. As a result, the resistance of the base polymer is increased. When the vinyl content of SBR is more than 30% by mass, the main chain of SBR has a polyethylene structure, the crystallinity becomes high and the molecular mobility is extremely lowered, and the compression set is deteriorated.

  The reason why carbon black having an average particle size of 150 nm or more and 500 nm or less is desirable is that it is a base polymer that is activated under a large current conduction condition by containing carbon black having a larger particle size than ordinary conductive carbon black. This is because the effect of suppressing the change in the dispersion state of carbon black caused by the molecular motion of the material appears. The above effect cannot be obtained with carbon black having an average particle size of less than 150 nm. In addition, carbon black having an average particle size of more than 500 nm causes huge carbon black to be exposed on the surface of the charging roller, causing the photoreceptor surface to leak in the latter half of the long-term use when the surface of the photoreceptor is worn. In addition, when the average particle size exceeds 500 nm, the above effect is not dramatically improved.

  Further, regarding the blending amount of carbon black having an average particle size of 150 nm or more and 500 nm or less, it is desirable to contain 40 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of rubber. If it is less than 40 mass parts, the effect which suppresses the change of the carbon black dispersion | distribution state by large current energization becomes scarce, and energization deterioration deteriorates. If it exceeds 100 parts by mass, the molecular mobility of the rubber is extremely lowered and the compression set is deteriorated. In addition to the above base polymer and carbon black, the charging roller of the present invention includes a filler, a plasticizer, a vulcanizing agent, a vulcanization accelerator, an anti-aging agent and the like within a range that does not impair the effects of the present invention. Can be optionally added. In particular, the vulcanizing agent is 0.1 parts by mass or more with respect to 100 parts by mass of rubber when sulfur is used as the vulcanizing agent in consideration of a desirable degree of vulcanization and reaction conditions for vulcanization with respect to the elastic modulus of the conductive layer rubber. It is preferable to add at 5 parts by mass or less. As for the vulcanization accelerator, it is preferable to use one or more sulfur vulcanization accelerators such as thiazole, thiuram, dithiocarbamic acid, thiourea, guanidine, and sulfanamide. More preferably, a thiuram type alone or a thiazole type and a thiuram combined type is preferred. With respect to the addition amount of the vulcanization accelerator, it is preferable to add 0.1 to 5 parts by mass with respect to 100 parts by mass of the rubber. Moreover, when using together a some vulcanization accelerator, it is preferable to add the addition amount of each vulcanization accelerator in 0.1 mass part or more and 2 mass parts or less with respect to 100 mass parts of rubber | gum. Next, regarding the degree of vulcanization, the unvulcanized rubber described in JIS K6300-2 is set by setting the vulcanizing agent, the addition amount of the vulcanization accelerator, the vulcanization time, the vulcanization temperature, etc. to the optimum values. It is preferable to measure the vulcanization curve and to design the optimum vulcanization point.

As the physical properties of the charging roller for achieving a long life in a high-temperature and high-humidity environment under the high-current energization condition of the present invention, the solubility parameter (SP value) of the conductive layer is 7.70 ≦ SP (cal ^1/2 / cm ^3/2 ) ≦ 8.70 and the hydrogen nucleus spin-spin relaxation time (T 2 HH) at 30 ° C. and 80% relative humidity is preferably 40 ≦ T 2 HH (μs) ≦ 200.

The reason why the SP value of the conductive layer is 7.70 ≦ SP (cal ^1/2 / cm ^3/2 ) ≦ 8.70 is that when the SP value is less than 7.70, the compatibility between the base polymer and the carbon black is deteriorated. The dispersion state of carbon black tends to change. Therefore, the deterioration of energization deteriorates. When the SP value exceeds 8.70, it becomes hydrophilic and water is easily adsorbed on the surface of the charging roller. Since this adsorbed water promotes an increase in resistance of the base polymer due to discharge deterioration, the deterioration of energization deteriorates.

  The reason why the hydrogen nuclear spin-spin relaxation time (T2HH) at a temperature of 30 ° C. and a relative humidity of 80% is 40 ≦ T2HH (μs) ≦ 200 is that the molecular mobility of the conductive layer in a high temperature and high humidity environment is low. (T2HH becomes smaller), the change in the carbon black dispersion state due to a large current becomes smaller (the current deterioration is good), but the decrease in molecular mobility leads to a decrease in elastic modulus and the compression set is worsened. On the other hand, when the molecular mobility increases (T2HH increases), the change in the carbon black dispersion state due to a large current increases (the deterioration of energization deteriorates), but the increase in molecular mobility increases the elastic modulus. Connection compression set is improved. Therefore, the range in which both the current deterioration and the compression set are compatible is the T2HH range.

  As the surface layer of the charging roller for achieving a long life in a high-temperature and high-humidity environment under the high-current energization conditions of the present invention, a surface layer containing polysiloxane having a fluorinated alkyl group and an oxyalkylene group is preferable. The oxyalkylene group is a divalent group (sometimes referred to as an “alkylene ether group”) having a structure represented by —O—R— (R: alkylene group). As this R (alkylene group), a C1-C6 alkylene group is preferable. This polysiloxane having an oxyalkylene group is obtained by condensation by hydrolysis of a hydrolyzable silane compound. Further, polysiloxane containing an oxyalkylene group and a fluorinated alkyl group is still more preferable. This is because the polyfluoride alkyl group has a polysiloxane structure that lowers the SP value on the outermost surface of the charging roller, and suppresses surface moisture adsorption in a high-temperature and high-humidity environment. Can be suppressed. Examples of the fluorinated alkyl group having a polysiloxane bond include those obtained by substituting part or all of the hydrogen atoms of a linear or branched alkyl group with a fluorine atom. Among these, a linear perfluoroalkyl group having 6 to 31 carbon atoms is preferable. The content of the fluorinated alkyl group in the polysiloxane is preferably 5.0 to 50.0% by mass with respect to the total mass of the polysiloxane, and the content of the oxyalkylene group in the polysiloxane is preferably polysiloxane. It is preferable that it is 5.0-70.0 mass% with respect to the total mass, and content of the siloxane part in polysiloxane is 20.0-90.0 mass% with respect to polysiloxane total mass. Is preferred. The polysiloxane preferably has a group capable of cationic polymerization. This is because, after the hydrolyzable silane compound is condensed by hydrolysis, the cationically polymerizable group is cleaved to crosslink the condensate, thereby increasing the crosslink density and the heat resistance and adhesion caused by the siloxane. This is because effects such as sex can be enhanced. The cationically polymerizable group means a cationically polymerizable organic group that generates an oxyalkylene group by cleavage, and examples thereof include cyclic ether groups such as epoxy groups and oxetane groups, and vinyl ether groups. Among these, an epoxy group is preferable from the viewpoint of availability and reaction control.

(Method for manufacturing charging roller)
A method for manufacturing the charging roller of the present invention will be described. The charging roller processing method is divided into a kneading method, a molding method, and a polishing method. Examples of the kneading method include a method of kneading the base polymer, conductive particles, vulcanization aid, plasticizer and filler with a pressure kneader, and then kneading the vulcanizing agent and vulcanization accelerator with a roll kneader. The molding method is a method of extruding into a roll with a single screw extruder, vulcanizing with a vulcanizing can, and press-fitting into a conductive support (core metal) coated with an adhesive, or directly coating the extrudate on the core metal. There is a method of vulcanizing in a hot air furnace. Examples of the polishing method include a method of polishing using a grindstone having the same size as the length (longitudinal width) of the charging roller and a method of polishing while traversing a thin grindstone in the longitudinal direction. As for the method for forming the surface layer, first, a hydrolyzable silane compound having a cationically polymerizable group, a hydrolyzable silane compound having a fluorinated alkyl group, and, if necessary, the other hydrolyzable compounds described above. A hydrolyzable condensate is obtained by hydrolyzing the silane compound in the presence of water. During the hydrolysis reaction, a hydrolyzable condensate having a desired degree of condensation can be obtained by controlling temperature, pH and the like. In the hydrolysis reaction, the degree of condensation may be controlled by using a metal alkoxide or the like as a catalyst for the hydrolysis reaction. Examples of the metal alkoxide include aluminum alkoxide, titanium alkoxide, zirconia alkoxide, and the like, and complexes thereof (acetylacetone complex and the like).

  Further, when obtaining the hydrolyzable condensate, the mixing ratio of the hydrolyzable silane compound having a cationically polymerizable group and the hydrolyzable silane compound having a fluorinated alkyl group, or these two hydrolyzable silanes The blending ratio when a hydrolyzable silane compound is further added to the compound is as follows. That is, the content of the fluorinated alkyl group in the obtained polysiloxane is 5.0 to 50.0% by mass with respect to the total mass of the polysiloxane, and the content of the oxyalkylene group is 5. It is preferably 0 to 70.0% by mass, and the content of the siloxane portion is preferably 20.0 to 90.0% by mass with respect to the total mass of the polysiloxane. Specifically, the hydrolyzable silane compound having a fluorinated alkyl group is preferably blended so as to be in the range of 0.5 to 20.0 mol% with respect to the total hydrolyzable silane compound, and in particular, 1 It is more preferable to mix | blend so that it may become the range of 0.0-10.0 mol%. Next, a coating solution for the surface layer containing the obtained hydrolyzable condensate is prepared, and the prepared coating solution for the surface layer is applied onto the support and the conductive layer formed on the support. When preparing the coating solution for the surface layer, an appropriate solvent may be used in addition to the hydrolyzable condensate in order to improve the coating property. Suitable solvents include, for example, alcohols such as ethanol and 2-butanol, ethyl acetate, methyl ethyl ketone, or a mixture thereof. Moreover, when applying the surface layer coating liquid onto the conductive elastic member, coating using a roll coater, dip coating, ring coating, or the like can be employed. Next, an active energy ray is irradiated to the surface layer coating solution coated on the conductive layer. Then, the cationically polymerizable group in the hydrolyzable condensate contained in the coating solution for the surface layer is cleaved, whereby the hydrolyzable condensate can be crosslinked. The hydrolyzable condensate is cured by crosslinking. The active energy ray is preferably ultraviolet rays. In addition, when the crosslinking reaction is performed using ultraviolet rays, deterioration of the conductive layer due to thermal history can be suppressed, so that a decrease in electrical characteristics of the conductive layer can also be suppressed. For irradiation with ultraviolet rays, a high-pressure mercury lamp, a metal halide lamp, a low-pressure mercury lamp, an excimer UV lamp, or the like can be used. Among these, an ultraviolet ray source having abundant light with an ultraviolet wavelength of 150 to 480 nm is used. The integrated light quantity of ultraviolet rays is defined as follows.

UV integrated light quantity [mJ / cm ² ] = UV intensity [mW / cm ² ] × irradiation time [s]
The adjustment of the integrated amount of ultraviolet light can be performed by the irradiation time, lamp output, distance between the lamp and the irradiated object, and the like. Moreover, you may give a gradient to integrated light quantity within irradiation time. When using a low-pressure mercury lamp, the integrated light quantity of ultraviolet rays can be measured using an ultraviolet integrated light quantity meter UIT-150-A or UVD-S254 manufactured by Ushio Electric Co., Ltd. When using an excimer UV lamp, Can be measured using an ultraviolet integrated light meter UIT-150-A or VUV-S172 manufactured by USHIO INC. In the crosslinking reaction, it is preferable that a cationic polymerization catalyst (polymerization initiator) is allowed to coexist from the viewpoint of improving the crosslinking efficiency. For example, since an epoxy group exhibits high reactivity with respect to an onium salt of a Lewis acid activated by an active energy ray, the above cationic polymerizable group is an epoxy group. It is preferable to use an onium salt of an acid.

The electrical resistance of the charging roller of the present invention is measured by applying a DC voltage while rotating the charging roller while being pressed against a metal drum (FIG. 4). It is desirable that it is 0.0 × 10 ⁴ Ω or more and 1.0 × 10 ⁷ Ω or less. If it is less than 1.0 × 10 ⁴ Ω, it is easy to cause photoconductor leakage, and if it exceeds 1.0 × 10 ⁷ Ω, charging failure occurs and it becomes difficult to place a desired potential on the photoconductor. A more preferable range of the electric resistance value is 5.0 × 10 ⁴ Ω or more and 1.0 × 10 ⁶ Ω or less.

(Electrophotographic equipment)
Next, the electrophotographic apparatus of the present invention will be described. The electrophotographic apparatus includes at least an electrophotographic photosensitive member, a charging unit that charges the surface of the photosensitive member, a latent image forming unit that exposes the photosensitive member to form a latent image, and a developing unit that supplies toner onto the photosensitive member. And a transfer means for transferring the toner image on the photosensitive member to the transfer target. Further, it can have a cleaning means for cleaning the transfer residual toner on the photosensitive member and a means for fixing the transfer target on which the toner image is formed.

As the electrophotographic photoreceptor, an electrophotographic photoreceptor having a photoconductive layer formed of an amorphous material mainly containing silicon atoms, or an organic electrophotographic film having a total thickness of the surface protective layer and the photosensitive layer of 20 μm or less. A photoconductor can be suitably used. As charging means, it is desirable to use roller charging using the charging roller of the present invention by proximity or contact charging. In addition to solving the deterioration of energization and permanent compression distortion, it has the effect of suppressing the occurrence of image flow. This is because the amount of discharge required to stabilize the electric potential on the electrophotographic photosensitive member is smaller than that of a general charging roller, so the amount of discharge products is reduced and the image flow is improved. . In particular, since the charging bias for stabilizing the surface potential of the photoconductor is increased, the effect of suppressing image flow due to a decrease in the discharge amount is enormous. The reason why the discharge amount is reduced is that the charging roller of the present invention has a conductive layer formed of SBR having a bound styrene content of 40% by mass or more and 60% by mass or less. Because it does not. When a high voltage is applied, current flows not only to the conductive path but also to the rubber component. For example, if the rubber of the resistance in such as NBR Toka hydrin (10 ⁸ ~10 ¹¹ Ω · about cm), rapidly to reduce the resistance of the high voltage application. Accordingly, the discharge amount is also increased, and the image flow is deteriorated.

  As an electrophotographic photosensitive member having a photoconductive layer formed of an amorphous material mainly composed of silicon atoms, a photoconductive layer and a surface protective layer are sequentially laminated on a base made of a conductive material such as Al or stainless steel. The thing which was done is mentioned. In addition to these layers, various functional layers such as a blocking layer, an antireflection layer, or an interface layer may be provided as necessary. For example, by providing a blocking layer, an interface layer, etc., and selecting a dopant such as a group III element or a group V element, it is possible to control the charging polarity such as positive charging and negative charging. In the present invention, a positively chargeable silicon drum is desirable from the viewpoint of image defects such as image blur due to a chargeable product. The substrate shape may be as desired according to the driving method of the electrophotographic photosensitive member. As the base material, conductive materials such as Al and stainless are generally used. However, for example, various conductive materials such as various plastics and ceramics, particularly those having no conductivity, are deposited to be conductive. Those provided with can also be used. Examples of the photoconductive layer include amorphous materials in which silicon atoms include hydrogen atoms and halogen atoms (abbreviated as “a-Si (H, X)”). Further, the thickness of the photoconductive layer is not particularly limited, but about 15 to 50 μm is appropriate in consideration of the manufacturing cost. Furthermore, in order to improve the characteristics, a plurality of layers may be formed such as a lower photoconductive layer and an upper photoconductive layer. In particular, for a light source having a relatively long wavelength and almost no wavelength variation, such as a semiconductor laser, an epoch-making effect appears by devising such a layer structure. The surface protective layer is generally formed of a-SiC (H, X), but may be a-C (H, X). Further, it is preferable to control so that the interface reflection between the photoconductive layer and the surface protective layer is continuously changed to suppress the interface reflection of the portion.

As an organic photoreceptor having a total thickness of the surface protective layer and the photosensitive layer of 20 μm or less, for example, a conductive layer, an intermediate layer, a photosensitive layer, and a surface protective layer are arranged in this order on a substrate made of a conductive material such as Al or stainless steel. An electrophotographic photosensitive member is provided. The binder resin for the conductive layer is preferably a thermosetting phenol resin. As the intermediate layer, the volume resistivity of the intermediate layer is preferably set to 1 × 10 ⁹ Ω · cm to 1 × 10 ¹³ Ω · cm in order to prevent charge injection from the conductive layer to the photosensitive layer. Non-crystalline copolymerizable nylon and the like are preferable. The thickness of the intermediate layer is preferably 0.1 μm to 2 μm. The photosensitive layer is separated into a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material even if it is a single layer type photosensitive layer containing the charge transporting material and the charge generating material in the same layer. The laminated photosensitive layer may be used. From the viewpoint of electrophotographic characteristics, the laminated photosensitive layer is preferred. The laminated photosensitive layer includes a normal layer type photosensitive layer laminated in the order of the charge generation layer and the charge transport layer from the support side, and a reverse layer type photosensitive layer laminated in the order of the charge transport layer and the charge generation layer from the support side. However, a normal photosensitive layer is preferred from the viewpoint of electrophotographic characteristics. The film thickness of the photosensitive layer is desirably 15 μm or less. The surface protective layer is formed by applying a chain polymerizable compound having an unsaturated double bond onto the photosensitive layer and then curing it. The chain polymerizable compound can be cured by heat, but can also be cured using ultraviolet rays or electron beams. The thickness of the protective layer is preferably 1 μm to 5 μm. As the latent image forming means, a laser exposure apparatus using a semiconductor laser is preferably employed. As for the latent image forming method, for example, it is preferable to adopt a back scan method when an amorphous silicon photoconductor is used, and an image scan method when a thin film organic photoconductor is used. As the developing means, in the case of an amorphous silicon photoreceptor, it is preferable to use a two-component developing system using a developing carrier. The toner is a pulverized toner containing a styrene copolymer and an ester wax, and is negatively charged. Further, it is preferable to use titanium oxide, silica, or strontium titanate as the external additive. As the carrier, it is desirable to use magnetic dispersion type carrier particles. Regarding the developing system, in the case of an electrophotographic apparatus using an amorphous silicon photoconductor, a regular developing system using a positively charged photoconductor and a negatively chargeable toner is used. In the case of an electrophotographic apparatus using a thin film organic photoconductor, a developing carrier is used. It is preferable to adopt a two-component development system using The toner includes colored resin particles containing a binder resin, a colorant, and other additives as necessary, and colored particles to which an external additive such as colloidal silica fine powder is externally added. Yes. The toner is a negatively charged polyethylene resin, and the volume average particle diameter is preferably 5 μm or more and 8 μm or less. As the carrier, for example, surface-oxidized or non-oxidized iron, nickel, cobalt, manganese, chromium, rare earth and other metals, and their alloys, or oxide ferrite can be preferably used. The production method is not particularly limited. The carrier has a weight average particle diameter of 20 to 50 μm, preferably 30 to 40 μm, and a resistivity of 10 ⁷ Ωcm or more, preferably 10 ⁸ Ωcm or more. The developing system of the electrophotographic apparatus using the thin film organic photoreceptor in the present invention is a regular developing system using a negatively charged photoreceptor and a negatively chargeable toner. As the transfer unit, it is preferable to use a transfer unit that directly transfers to a transfer target (paper, medium such as OHP) using a transfer roller, or a transfer unit that performs primary transfer to an intermediate transfer member such as a transfer belt. As the cleaning means, it is preferable to use a blade cleaning method using a blade-shaped member, a brush cleaning method using a brush-shaped member, or a method using both. The fixing unit is not particularly limited as long as the transferred toner image is fixed by heating, pressing, or heating and pressing.

  The present invention will be described below with reference to production examples and examples, but the present invention is not limited to these examples unless it exceeds the gist.

"raw materials"
Eleven types of SBR with different amounts of bound styrene (mass%) and vinyl (mass%) were obtained. The structure of SBR was determined using an infrared spectrophotometer. The amount of bound styrene was determined by the Hampton method, and the amount of bound vinyl was determined by the Morero method. The proportion of the microstructure of SBR is based on the case where the amount of bound styrene + the amount of bound vinyl + the amount of bound cis + the amount of bound trans = 100 (mass%). Table 1 shows the measurement results of the microstructures of SBR1 to SBR11.

  Regarding acrylonitrile-butadiene rubber (NBR), a acrylonitrile-butadiene rubber having a combined acrylonitrile content of 20% by mass and a Mooney viscosity (ML1 + 4: 100 ° C.) of 43 was obtained. Regarding epichlorohydrin rubber (ECO), EO (ethylene oxide) EP (epichlorohydrin) AGE (allyl glycidyl ether) ratio of EO: EP: AGE = 56: 40: 4 was obtained (Table 1). ).

Carbon black (CB) having different average particle diameter (nm), nitrogen adsorption specific surface area (m ² / g), and DBP oil absorption (ml / 100 g) was obtained. The average particle size of CB was measured with an electron microscope and obtained as an arithmetic average value. The nitrogen adsorption specific surface area was measured using a flow-type specific surface area automatic measuring device Flowsorb III 2310 (manufactured by Shimadzu Corporation), and measured three times for one sample to obtain an average value. The DBP oil absorption amount was measured with an absorption amount measuring device S-410 (manufactured by Asahi Soken Co., Ltd.), measured three times per sample, and the average value was obtained. Table 2 shows the measurement results of physical properties of CB1 to CB12.

"Production Example 1"
(Production of charging roller)
100 parts by weight of SBR1 (bound styrene content 40% by weight: vinyl content 30% by weight: cis-trans-butadiene 30% by weight), CB1 (average particle size: 160 nm: nitrogen specific surface area 10 m ² / g: DBP oil absorption 30 ml / 40 parts by mass of 100 g) and CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) with respect to 3.5 parts by mass (see Table 1, Table 2 and Table 3) After adding 6 parts by mass of zinc oxide, 1.5 parts by mass of zinc stearate, 8 parts by mass of plasticizer, and 15 parts by mass of calcium carbonate (manufactured by Maruo Calcium Co., Ltd .: Nanox # 30), the mixture was kneaded for 30 minutes with a pressure kneader. Then, 2.3 parts by mass of sulfur and 2 parts by mass of vulcanization accelerator TMTM were added and further kneaded with an open roll for 15 minutes. The rubber mixture was extruded into a cylindrical shape with a rubber extruder, cut into a length of 400 mm, and primary vulcanized at 160 ° C. for 40 minutes using a vulcanizing can to obtain a primary vulcanized tube of a conductive layer. A thermosetting adhesive is applied to the surface of a conductive support made of SUS (FIG. 1 (A)), and is inserted into the primary vulcanization tube obtained above. Subsequent vulcanization and curing of the adhesive was carried out to form an unpolished conductive layer on the conductive support. After cutting both ends of this unpolished conductive layer to a length of 320 mm, the rubber portion was polished with a rotating grindstone to obtain a charging roller base layer.

Next, 27.84 g (0.1 mol) of glycidoxypropyltriethoxysilane (GPTES) as a hydrolyzable silane compound, 17.83 g (0.1 mol) of methyltriethoxysilane (MTES), and tridecafluoro-1, 17.68 g (0.0151 mol (equivalent to 7 mol% with respect to the total amount of hydrolyzable silane compound)) of 1,2,2-tetrahydrooctyltriethoxysilane (FTS, carbon number 6 of perfluoroalkyl group) and water 17. After mixing 43 g and 37.88 g of ethanol, the mixture was stirred at room temperature. Subsequently, the hydrolyzable silane compound condensate was obtained by heating and refluxing for 24 hours. By adding this condensate to a mixed solvent of 2-butanol / ethanol, a condensate-containing alcohol solution I having a solid content of 7% by mass was prepared. 0.35 g of an aromatic sulfonium salt (trade name: Adekaoptomer SP-150, manufactured by Asahi Denka Kogyo Co., Ltd.) as a photocationic polymerization initiator is added to 100 g of this condensate-containing alcohol solution I. The coating solution for surface layer was prepared by adding to the above. The dipping coating a surface layer coating liquid to the charging roller underlayer according, to which the ultraviolet rays having a wavelength of 254nm is integrated light amount irradiated to be 9000 mJ / cm ^2, curing the surface layer coating liquid (cross-linking reaction The surface layer was formed by drying and drying. A low-pressure mercury lamp manufactured by Harrison Toshiba Lighting Co., Ltd. was used for ultraviolet irradiation. Thus, Production Example 1 charging roller was obtained (FIG. 1B).

"Production Examples 2-31"
A charging roller was produced in the same manner as in Production Example 1 except that the base polymer blend and the carbon black blend described in Table 3 to Table 5 were changed.

"Example 1"
(SP value measurement)
The slice was cut out from the inside of the conductive layer of the charging roller of Production Example 1, and immersed in a solvent with known SP for 2 days, and the degree of swelling was measured. For example, isopentane (SP value: 6.625), 2,2,4-trimethylpentane (SP value: 6.849), 2,2,3-trimethylbutane (SP value: 6.942), n-pentane ( SP value: 7.012), n-heptane (SP value: 7.242), n-hexane (SP value: 7.423), n-octane (SP value: 7.554), n-decane (SP value) : 7.722), diethyl ether (SP value: 7.743), methylcyclohexane (SP value: 7.816), isobutyl-n-butyrate (SP value: 7.822), n-dodecane (SP value: 7) 832), n-hexadecane (SP value: 7.930), cyclohexane (SP value: 8.182), ethyl-n-butyrate (SP value: 8.238), n-butyl acetate (SP value: 8.283), 11-trichloroethane (SP value: 8.544), carbon tetrachloride (SP value: 8.582), n-propyl acetate (SP value: 8.678), toluene (SP value: 8.907), methyl ethyl ketone (SP Value: 9.038), methyl isobutyl ketone (SP value: 9.557), and (see Japan Society for Synthetic Organic Chemistry, Solvent Pocket Book). The degree of swelling is calculated from the following formula.

Swelling degree = (section specific gravity before solvent immersion) / (section specific gravity after solvent immersion) × 100 (Formula 1)
The SP value of the solvent having the highest degree of swelling of the slice was taken as the SP value of the conductive layer of the charging roller.
As a result of the measurement in Example 1, the SP value of the charging roller was 7.722 (Table 6).

(Measurement of T2HH)
The measurement method of T2HH is a sample obtained by scraping the conductive layer of the charging roller of Production Example 1, using a Bruker (trade name: minispec) pulse NMR apparatus, and T ₂ (T2HH) at a temperature of 30 ° C. and a relative humidity of 80%. Was measured. T2HH is a weighted average of the T ₂ components obtained. As a method for obtaining T2HH, an echo intensity curve obtained by using the CPMG method at a temperature of 30 [deg.] C. and a relative humidity of 80% in the spin-spin relaxation time obtained by pulse NMR measurement is measured by the least square method. Ask. A CPMG method (90 ° −τ− (180 ° −2τ) n−) at a temperature of 23 ° C. under the conditions of a hydrogen nucleus as a measurement nucleus, a measurement frequency of 20 MHz, a 90 ° pulse width of 2.82 μsec, and a pulse interval = 0.1 msec. 180 ° pulse method). The echo intensity curve obtained here is obtained by the least square method. The echo intensity S observed by the CPMG method is given by the following equation.

Here, t represents time (τ), S0i represents the echo intensity at t = 0 of each i component (i = S, L), T2i represents T2 of each i component, and Σ represents the sum for i.
The component fraction Fj of each component j is

It is expressed.

  As a result of measurement in Example 1, the value of T2HH of the charging roller was 120 μS (Table 6).

(Measurement of energization degradation index)
The electrification idle rotating machine shown in FIG. 2 was mounted with the charging roller and aluminum drum of Production Example 1, and an energization deterioration acceleration test was performed in a high temperature and high humidity environment (H / H: temperature 30 ° C. and relative humidity 80%). . The energization conditions were a DC current of 290 μA, an AC total current of 3.3 mA, and 8 hours / day for 3 days. The electrical resistance value of the charging roller was measured seven times before energization, 8 hours, 8 hours morning, 16 hours, 16 hours morning, 24 hours later, 24 hours morning, and the electrical resistance values plotted in terms of time are as follows ( Fitting was performed using equation 3) (FIG. 3).

R (electric resistance value: Ω) = R ₀ × exp (0.0001 × A × T) (Formula 3)
Here, R (electric resistance measurement value: Ω), R ₀ (initial electric resistance value: Ω), A (energization degradation index), and T (time).

The value A was used as an index of the deterioration of energization.
As an evaluation of A,
A: 0 <| A | (Absolute value of A) <100: Deterioration of energization is very good.
○: 100 ≦ | A | ≦ 220: Deterioration of energization is a level that can withstand practical use.
×: 220 <| A |: Deterioration of energization deteriorates and is not at a level that can withstand practical use.
It was.

  The electrical resistance value is measured by bringing the charging roller into contact with the aluminum drum, applying a load of 300 g on both ends of the conductive support so that the contact area is uniform, rotating the aluminum drum, and the conductive roller Y being driven. While rotating, a current flowing by applying a DC voltage of 300 V was measured, and an electric resistance value (Ω) of the conductive roller was obtained (FIG. 4).

  As for the measurement result of Example 1, the evaluation of the energization deterioration index was ◎ (Table 6).

(Drum potential measurement)
The Canon copier GP405 was modified and the process speed was set to 400 mm / s. The charging bias was supplied from an external power source. The charging conditions, exposure method, and developing means were set to the methods / conditions described below according to the photosensitive drum. The modified machine is shown in FIG. The charging roller and photoconductor of Production Example 1 were mounted, and a paper passing durability test was performed in a high temperature and high humidity environment (H / H: temperature 30 ° C., relative humidity 80%). An evaluation method for measuring the drum potential is shown below.
○: The drum potential before endurance of paper passing and the drum potential after endurance of 250,000 sheets were measured, and there was no decrease in drum potential from the initial stage.
X: A sudden drop in drum potential occurred during paper passing durability.
Leak: Photoconductor leak occurred in the second half of the end of paper passing.
Two types of photoreceptors were evaluated.

The amorphous silicon (a-Si) photoconductor is a positively charged a-Si photoconductor that is sequentially laminated on the surface of a conductive support made of φ80 mm Al, and includes a negative charge blocking layer and a photoconductive layer. A photosensitive drum composed of a surface protective layer was used. Regarding the toner and carrier, the toner is a negatively charged pulverized toner in which an ester wax and a colorant are dispersed in a styrene copolymer, and silica, titanium oxide, and strontium titanate are used as external additives. The average particle size of the toner was 6.8 μm. As the carrier, magnetic particle-dispersed carrier particles in which magnetite was dispersed in a phenol resin were used. The average particle size of the carrier is 35 [mu] m, and the resistivity was 10 ⁹ [Omega] cm. As the developing means, a two-component developing system using a developing carrier was used. The charging conditions are DC voltage +600 V, AC voltage 1.5 kV, and AC frequency 3.5 kHz. The exposure method was changed to the back scan method.

For the thin film organic photoreceptor (OPC), an aluminum cylinder containing an electron transporting organic compound with a layer thickness of 1 μm, a phthalocyanine charge generation layer with a layer thickness of 0.15 μm, and a triarylamine system with a layer thickness of 10 μm. It is a photoreceptor having a photosensitive layer composed of a charge transport layer and a photopolymerizable protective layer having a layer thickness of 5 μm. The results are shown in Table 2. The toner used was a pulverized toner in which carbon black was dispersed as a colorant in a negatively charged polyethylene resin externally added with silica and titanium oxide. The average particle size of the toner was 7.0 μm. The carrier used oxide ferrite. The average particle diameter of the carrier was 30 μm, and the resistivity was 10 ⁸ Ωcm. As the developing means, a two-component developing system using a developing carrier was used. Charging conditions were set to a DC voltage of −750 V, an AC voltage of 2.0 kV, and an AC frequency of 3.2 kHz, and an exposure method was an image scanning method.

  The measurement results of Example 1 were evaluated as “good” for both the a-Si photosensitive member and the OPC (Table 6).

(Compression set test)
The charging roller of Production Example 1 was brought into contact with the photoreceptor unit of Canon Co., Ltd. GP 405 and left in a high temperature and high humidity environment (H / H: temperature 30 ° C., relative humidity 80%) for 1 month. The contacted photoconductor is the amorphous silicon drum and the thin film organic photoconductor described in the drum potential test. Using the GP405 modified machine, an initial image was printed with a halftone image under the same conditions as in the drum potential test. The evaluation method of the compression set test is shown below.
A: No charging roller pitch image defect on the halftone image.
◯: Although charging roller pitch image defects slightly occur on the halftone image, there is no practical problem.
X: An image defect of the charging roller pitch occurs on the halftone image, which is not a practical level.
The test results of Example 1 were evaluated as ◎ for both the a-Si photoreceptor and OPC (Table 6).

"Example 2"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR2 (bound styrene content 50% by weight: vinyl content 30% by weight: cis-trans-butadiene 20% by weight), CB2 (average particle size: 250 nm: nitrogen specific surface area 9 m ^2). / g: DBP oil absorption 26 ml / 100 g) 40 parts by mass, CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 3.8 parts by mass (Tables 1 and 2) And Table 3), except for the change to the charging roller of Production Example 2), the SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.
The SP value was 7.822. T2HH was 80 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 3"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR3 (bonded styrene content 60% by weight: vinyl content 30% by weight: cis-trans-butadiene 10% by weight), CB3 (average particle size: 300 nm: nitrogen specific surface area 8 m ^2). / g: DBP oil absorption 22 ml / 100 g) 40 parts by mass, CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 4 parts by mass (Tables 1, 2 and Tables) 3)) (SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, compression permanent, etc.) A strain test was performed.

  The SP value was 8.283. T2HH was 40 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

Example 4
The material of the conductive layer of the charging roller is 100 parts by weight of SBR4 (40% by weight of bound styrene: 10% by weight of vinyl: 50% by weight of cis-trans-butadiene), CB4 (average particle size: 470 nm: specific surface area of nitrogen 5 m ²⁾ / g: DBP oil absorption 25 ml / 100 g) 40 parts by mass, CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 4.2 parts by mass (Tables 1 and 2) And Table 3), except for the change to the charging roller of Production Example 4), the SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 7.743. T2HH was 150 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 5"
The material of the conductive layer of the charging roller is 100 parts by mass of SBR5 (50% by mass of bound styrene: 10% by mass of vinyl: 40% by mass of cis-trans-butadiene), CB5 (average particle size: 500 nm: nitrogen specific surface area of 3 m ^2). / g: DBP oil absorption 15 ml / 100 g) 40 parts by mass, CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 4.5 parts by mass (Tables 1 and 2) And Table 3), except for changing to the charging roller of Production Example 5), in the same manner as in Example 1, SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 7.832. T2HH was 100 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 6"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR6 (bound styrene content 60% by weight: vinyl content 10% by weight: cis-trans-butadiene 30% by weight), CB1 (average particle size: 160 nm: nitrogen specific surface area 10 m ^2). / g: 70 parts by mass of DBP oil absorption 30 ml / 100 g) and 5 parts by mass of CB7 (average particle size: 38 nm: nitrogen specific surface area 42 m ² / g: DBP oil absorption 500 ml / 100 g) (Tables 1, 2 and Tables) 3)) (SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, compression permanent, etc.) A strain test was performed.

  The SP value was 8.554. T2HH was 50 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 6).

"Example 7"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR7 (bound styrene content 40% by weight: vinyl content 0% by weight: cis-trans-butadiene 60% by weight), CB2 (average particle size: 250 nm: nitrogen specific surface area 9 m ^2). / g: 70 parts by mass of DBP oil absorption 26 ml / 100 g) and 5.2 parts by mass of CB7 (average particle size: 38 nm: nitrogen specific surface area 42 m ² / g: DBP oil absorption 500 ml / 100 g) (Tables 1 and 2) And Table 3), except for changing to the charging roller of Production Example 7), the SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 7.816. T2HH was 180 μS. The evaluation of the energization deterioration index was ○. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 8"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR8 (bound styrene content 50% by weight: vinyl content 0% by weight: cis-trans-butadiene 50% by weight), CB3 (average particle size: 300 nm: nitrogen specific surface area 8 m ^2). / g: DBP oil absorption 22 ml / 100 g) 70 parts by mass, CB7 (average particle size: 38 nm: nitrogen specific surface area 42 m ² / g: DBP oil absorption 500 ml / 100 g) 5.5 parts by mass (Tables 1 and 2) And Table 3), except for the change to the charging roller of Production Example 8), the SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 7.930. T2HH was 120 μS. The evaluation of the energization deterioration index was ○. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 6).

"Example 9"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR9 (bound styrene content 60% by weight: vinyl content 0% by weight: cis-trans-butadiene 40% by weight), CB4 (average particle size: 470 nm: nitrogen specific surface area 5 m ^2. / g: 70 parts by mass of DBP oil absorption 25 ml / 100 g) and 5.7 parts by mass of CB7 (average particle size: 38 nm: nitrogen specific surface area 42 m ² / g: DBP oil absorption 500 ml / 100 g) (Tables 1 and 2) And Table 3) except for the change to the charging roller of Production Example 9), the SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 8.678. T2HH was 60 μS. The evaluation of the energization deterioration index was ○. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 6).

"Example 10"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR1 (40% by weight of bound styrene: 30% by weight of vinyl: 30% by weight of cis-trans-butadiene), CB5 (average particle size: 500 nm: nitrogen specific surface area of 3 m ^2). / g: 70 parts by mass of DBP oil absorption 15 ml / 100 g) and 6 parts by mass of CB7 (average particle size: 38 nm: nitrogen specific surface area 42 m ² / g: DBP oil absorption 500 ml / 100 g) (Tables 1, 2 and Tables) 3)) (SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, compression permanent, in the same manner as in Example 1 except that it was changed to the charging roller of Production Example 10). A strain test was performed.

  The SP value was 7.722. T2HH was 125 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 11"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR2 (bound styrene content 50% by weight: vinyl content 30% by weight: cis-trans-butadiene 20% by weight), CB1 (average particle size: 150 nm: nitrogen specific surface area 10 m ^2). / g: 100 parts by mass of DBP oil absorption 30 ml / 100 g) and 2 parts by mass of CB8 (average particle size: 40 nm: nitrogen specific surface area 48 m ² / g: DBP oil absorption 130 ml / 100 g) (Tables 1, 2 and Tables) 3)) (SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, compression permanent, in the same manner as in Example 1 except that it was changed to the charging roller of Production Example 11). A strain test was performed.

  The SP value was 7.822. T2HH was 83 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 12"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR3 (bound styrene content 60% by weight: vinyl content 30% by weight: cis-trans-butadiene 10% by weight), CB2 (average particle size: 250 nm: nitrogen specific surface area 9 m ^2). / g: DBP oil absorption 26 ml / 100 g) 100 parts by mass, CB8 (average particle size: 40 nm: nitrogen specific surface area 48 m ² / g: DBP oil absorption 130 ml / 100 g) 2.3 parts by mass (Tables 1 and 2) And Table 3), except for changing to the charging roller of Production Example 12), in the same manner as in Example 1, SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 8.283. T2HH was 42 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 13"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR4 (40% by weight of bound styrene: 10% by weight of vinyl: 50% by weight of cis-trans-butadiene), CB3 (average particle size: 300 nm: specific surface area of nitrogen 8 m ^2). / g: DBP oil absorption 22 ml / 100 g) 100 parts by mass, CB8 (average particle size: 40 nm: nitrogen specific surface area 48 m ² / g: DBP oil absorption 130 ml / 100 g) 2.4 parts by mass (Tables 1 and 2) And Table 3), except for the change to the charging roller of Production Example 13), the SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 7.743. T2HH was 154 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 14"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR5 (bound styrene content 50 mass%: vinyl content 10 mass%: cis-trans-butadiene 40 mass%), CB4 (average particle size: 470 nm: nitrogen specific surface area 5 m ^2. / g: DBP oil absorption 25 ml / 100 g) 100 parts by mass, CB8 (average particle size: 40 nm: nitrogen specific surface area 48 m ² / g: DBP oil absorption 130 ml / 100 g) 2.6 parts by mass (Tables 1 and 2) And Table 3), except for changing to the charging roller of Production Example 14), in the same manner as in Example 1, SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 7.832. T2HH was 106 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 15"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR6 (bonded styrene content 60% by weight: vinyl content 10% by weight: cis-trans-butadiene 30% by weight), CB5 (average particle size: 500 nm: nitrogen specific surface area 3 m ^2). / g: DBP oil absorption of 15 ml / 100 g) 100 parts by mass, CB8 (average particle diameter: 40 nm: nitrogen specific surface area of 48m ² / g: DBP oil absorption of 130 ml / 100 g) 3 parts by mass (Table 1, Table 2 and Table 3)) (SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, compression permanent, in the same manner as in Example 1 except that the charging roller was changed to the charging roller of Production Example 15). A strain test was performed.

  The SP value was 8.554. T2HH was 54 μS. The evaluation of the energization deterioration index was ○. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 6).

"Example 16"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR7 (bonded styrene content 40% by weight: vinyl content 0% by weight: cis-trans-butadiene 60% by weight), CB1 (average particle size: 150 nm: nitrogen specific surface area 10 m ^2). / g: DBP oil absorption 30 ml / 100 g) 40 parts by mass, CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 3.5 parts by mass, CB8 (average particle size) : 43 nm: Nitrogen specific surface area 42 m ² / g: DBP oil absorption 115 ml / 100 g) was changed to 12 parts by mass (see Tables 1, 2 and 3) (changed to the charging roller of Production Example 16). In the same manner as in Example 1, SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, and compression set test were performed.

  The SP value was 7.816. T2HH was 196 μS. The evaluation of the energization deterioration index was ○. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 6).

"Example 17"
As the material of the conductive layer of the charging roller, 100 parts by weight of SBR8 (bound styrene content 50% by weight: vinyl content 0% by weight: cis-trans-butadiene 50% by weight), CB2 (average particle size: 250 nm: nitrogen specific surface area 9 m ²⁾ / g: DBP oil absorption 26 ml / 100 g) 40 parts by mass, CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 3.6 parts by mass, CB8 (average particle size) : 43 nm: nitrogen specific surface area 42 m ² / g: DBP oil absorption 115 ml / 100 g) was changed to 12 parts by mass (see Tables 1, 2 and 3) (changed to the charging roller of Production Example 17). In the same manner as in Example 1, SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, and compression set test were performed.

  The SP value was 7.930. T2HH was 134 μS. The evaluation of the energization deterioration index was ○. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 6).

"Example 18"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR9 (bound styrene content 60% by weight: vinyl content 0% by weight: cis-trans-butadiene 40% by weight), CB3 (average particle size: 300 nm: nitrogen specific surface area 8 m ^2). / g: DBP oil absorption 22 ml / 100 g) 40 parts by mass, CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 3.7 parts by mass, CB8 (average particle diameter) : 43 nm: nitrogen specific surface area of 42m ² / g: DBP oil absorption 115 ml / 100 g) 12 parts by weight (Table 1, except that the see Table 2 and Table 3) (changes to the charging roller of preparation 18) is carried out In the same manner as in Example 1, SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, and compression set test were performed.

  The SP value was 8.678. T2HH was 69 μS. The evaluation of the energization deterioration index was ○. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 6).

“Comparative Example 1”
As the material for the conductive layer of the charging roller, 100 parts by weight of SBR1 (bonded styrene content 40% by weight: vinyl content 30% by weight: cis-trans-butadiene 30% by weight) and CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ²⁾ / g: DBP oil absorption amount of 495 ml / 100 g) was changed to 7 parts by mass (see Tables 1, 2 and 5) (changed to the charging roller of Production Example 19). SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, and compression set test were performed.

  The SP value was 7.722. T2HH was 240 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 7). Since the carbon black having an average particle size of 150 nm or more and 500 nm or less was not contained, it is considered that the current deterioration deteriorated.

“Comparative Example 2”
The material of the conductive layer of the charging roller is 100 parts by weight of SBR2 (50% by weight of bound styrene: 30% by weight of vinyl: 20% by weight of cis-trans-butadiene), and CB7 (average particle size: 38 nm: specific surface area of nitrogen 42 m ^2). / g: DBP oil absorption 500ml / 100g) was changed to 12 parts by mass (see Tables 1, 2 and 5) (changed to the charging roller of Production Example 20), and the same method as in Example 1, SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, and compression set test were performed.

  The SP value was 7.822. T2HH was 160 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 7). Since the carbon black having an average particle size of 150 nm or more and 500 nm or less was not contained, it is considered that the current deterioration deteriorated.

“Comparative Example 3”
The material of the conductive layer of the charging roller is 100 parts by weight of SBR3 (bound styrene content 60% by weight: vinyl content 30% by weight: cis-trans-butadiene 10% by weight), CB8 (average particle size: 43 nm: nitrogen specific surface area 42 m ^2). / g: DBP oil absorption 115 ml / 100 g) was changed to 30 parts by mass (see Table 1, Table 2 and Table 5) (changed to the charging roller of Production Example 21), in the same manner as in Example 1, SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, and compression set test were performed.

  The SP value was 8.283. T2HH was 80 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 7). Since the carbon black having an average particle size of 150 nm or more and 500 nm or less was not contained, it is considered that the current deterioration deteriorated.

“Comparative Example 4”
The material of the conductive layer of the charging roller is 100 parts by weight of SBR4 (bound styrene content 40% by weight: vinyl content 10% by weight: cis-trans-butadiene 50% by weight), CB9 (average particle size: 40 nm: nitrogen specific surface area 48 m ^2). / g: DBP oil absorption 130 ml / 100 g) was changed to 35 parts by mass (see Tables 1, 2 and 5) (changed to the charging roller of Production Example 22), in the same manner as in Example 1, SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, and compression set test were performed.

  The SP value was 7.743. T2HH was 300 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 7). Since the carbon black having an average particle size of 150 nm or more and 500 nm or less was not contained, it is considered that the current deterioration deteriorated.

“Comparative Example 5”
The material of the conductive layer of the charging roller is 100 parts by weight of SBR5 (bound styrene content 50 mass%: vinyl content 10 mass%: cis-trans-butadiene 40 mass%), CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ^2. / g: DBP oil absorption of 495 ml / 100 g) and 3 parts by mass, CB10 (average particle diameter: 80 nm: nitrogen specific surface area of 24m ² / g: DBP oil absorption of 28 ml / 100 g) 40 parts by mass (Table 1, Table 2 and Table 5)) (SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, compression permanent, etc.) A strain test was performed.

  The SP value was 7.832. T2HH was 203 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 7). Since the carbon black having an average particle size of 150 nm or more and 500 nm or less was not contained, it is considered that the current deterioration deteriorated.

“Comparative Example 6”
The material of the conductive layer of the charging roller SBR6 (bonded styrene content 60% by weight: vinyl content 10 wt% cis-trans - butadiene 30% by weight) 100 parts by mass, CB6 (average particle diameter: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 3.5 parts by mass, CB11 (average particle size: 120 nm: nitrogen specific surface area 12 m ² / g: DBP oil absorption 41 ml / 100 g) 40 parts by mass (Tables 1 and 2) And Table 5), except for the change to the charging roller of Production Example 24), the SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 8.554. T2HH was 100 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 7). Since the carbon black having an average particle size of 150 nm or more and 500 nm or less was not contained, it is considered that the current deterioration deteriorated.

“Comparative Example 7”
The material of the conductive layer of the charging roller is 100 parts by weight of SBR7 (bonded styrene content 40% by weight: vinyl content 0% by weight: cis-trans-butadiene 60% by weight), CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ^2. / g: DBP oil absorption 495 ml / 100 g) 3.8 parts by mass, CB12 (average particle size: 620 nm: nitrogen specific surface area 5 m ² / g: DBP oil absorption 20 ml / 100 g) 40 parts by mass (Tables 1 and 2) And Table 5), except for changing to the charging roller of Production Example 25), the SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 7.816. T2HH was 360 μS. The evaluation of the energization deterioration index was ○. In the drum potential evaluation, a-Si and OPC leaked the photoreceptor. The evaluation of compression set was ◎ for both a-Si and OPC (Table 7). Since carbon black having an average particle diameter of 500 nm or more was contained, it is considered that a photoreceptor leak occurred.

"Comparative Example 8"
The material of the conductive layer of the charging roller is 100 parts by weight of SBR8 (bound styrene content 50 mass%: vinyl content 0 mass%: cis-trans-butadiene 50 mass%), CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ^2. / g: DBP oil absorption 495 ml / 100 g) 3 parts by mass, CB7 (average particle size: 38 nm: nitrogen specific surface area 42 m ² / g: DBP oil absorption 500 ml / 100 g) 20 parts by mass (Tables 1, 2 and Tables) 5)) (SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, compression permanent) A strain test was performed.

  The SP value was 7.930. T2HH was 245 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 7). Since the carbon black having an average particle size of 150 nm or more and 500 nm or less was not contained, it is considered that the current deterioration deteriorated.

"Comparative Example 9"
As the material of the conductive layer of the charging roller, 100 parts by mass of SBR9 (bound styrene content 60% by mass: vinyl content 0% by mass: cis-trans-butadiene 40% by mass), CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ²⁾ / g: 3 parts by mass of DBP oil absorption 495 ml / 100 g) and 30 parts by mass of CB8 (average particle size: 43 nm: nitrogen specific surface area 42 m ² / g: DBP oil absorption 115 ml / 100 g) (Tables 1, 2 and Tables) 5)) (SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, compression permanent, etc. in the same manner as in Example 1 except that the charging roller was changed to the charging roller of Production Example 27). A strain test was performed.

  The SP value was 8.678. T2HH was 125 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 7). Since the carbon black having an average particle size of 150 nm or more and 500 nm or less was not contained, it is considered that the current deterioration deteriorated.

"Comparative Example 10"
As the material of the conductive layer of the charging roller, 100 parts by weight of SBR10 (bound styrene content 30% by weight: vinyl content 0% by weight: cis-trans-butadiene 70% by weight), CB3 (average particle size: 300 nm: nitrogen specific surface area 8 m ²⁾ / g: DBP oil absorption 22 ml / 100 g) 60 parts by mass, CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 3 parts by mass (Tables 1, 2 and Tables) 5)) (SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, compression permanent, etc., in the same manner as in Example 1 except that the charging roller was changed to the charging roller of Production Example 28). A strain test was performed.

  The SP value was 7.554. T2HH was 210 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 7). Since SBR having a bound styrene content of less than 40% by mass was used, it is considered that the current deterioration deteriorated.

“Comparative Example 11”
The material of the conductive layer of the charging roller is 100 parts by weight of SBR11 (70% by weight of bound styrene: 0% by weight of vinyl: 30% by weight of cis-trans-butadiene), CB3 (average particle size: 300 nm: specific surface area of nitrogen 8 m ^2). / g: DBP oil absorption 22 ml / 100 g) 60 parts by mass, CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) 2.5 parts by mass (Tables 1 and 2) And (see Table 5), except for the change to the charging roller of Production Example 29), the SP value measurement, T2HH measurement, energization deterioration index evaluation, drum potential evaluation, A compression set test was performed.

  The SP value was 8.907. T2HH was 30 μS. The evaluation of the energization deterioration index was ◎. The drum potential was evaluated as “good” for both a-Si and OPC. The evaluation of compression set was x for both a-Si and OPC (Table 7). It is considered that compression set was deteriorated because SBR having a bound styrene content of 60% by mass or more was used.

“Comparative Example 12”
The material of the conductive layer of the charging roller is NBR (20% by mass of bound acrylonitrile: Mooney viscosity (ML1 + 4: 100 ° C.) 43), 100 parts by mass, CB3 (average particle size: 300 nm: nitrogen specific surface area 8 m ² / g: DBP 60 parts by mass of oil absorption 22 ml / 100 g) and 2.7 parts by mass of CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) (see Table 1, Table 2 and Table 5) ) (Except for the charging roller of Production Example 30), in the same manner as in Example 1, SP value measurement, T2HH measurement, energization degradation index evaluation, drum potential evaluation, compression set test Went.

  The SP value was 9.073. T2HH was 360 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ◎ for both a-Si and OPC (Table 7). Since materials other than SBR having a bound styrene content of 40% by mass or more and 60% by mass or less were used, it is considered that the deterioration of energization deteriorated.

"Comparative Example 13"
The material of the conductive layer of the charging roller is 100 parts by mass of ECO (EO: EP: AGE = 56: 40: 4), CB3 (average particle size: 300 nm: nitrogen specific surface area 8 m ² / g: DBP oil absorption 22 ml / 100 g) Was changed to 60 parts by mass, and CB6 (average particle size: 30 nm: nitrogen specific surface area 1270 m ² / g: DBP oil absorption 495 ml / 100 g) was changed to 1 part by mass (see Table 1, Table 2, and Table 5). Except for the change to the charging roller), the SP value, T2HH, energization degradation index, drum potential, and compression set test were performed in the same manner as in Example 1.

  The SP value was 9.038. T2HH was 760 μS. The evaluation of the energization deterioration index was x. The drum potential was evaluated as x for both a-Si and OPC. The evaluation of compression set was ○ for both a-Si and OPC (Table 7). Since materials other than SBR having a bound styrene content of 40% by mass or more and 60% by mass or less were used, it is considered that the deterioration of energization deteriorated.

(A) It is the schematic of the shape of an electroconductive support body. (B) It is the schematic of the shape of a charging roller. It is a schematic diagram of an energization idling machine of the present invention. It is a graph of the electrical resistance value of the charging roller and the energization time obtained by the energization deterioration acceleration test. It is the schematic of a charging roller electrical resistance measuring apparatus. 1 is a schematic view of an electrophotographic apparatus of the present invention.

Explanation of symbols

1 Charging roller 2 Aluminum drum 3 Charging bias power supply (AC + DC)
4 Drum drive motor 5 Spring pressure 6 Electrophotographic photosensitive member 7 Axis 8 Exposure means 9 Development means 10 Transfer means 11 Cleaning means 12 Fixing means P Transfer material

Claims (7)

  In a charging roller having a conductive layer on a conductive support, the conductive layer is formed of styrene butadiene rubber (SBR) having an amount of bound styrene of 40% by mass to 60% by mass and having an average particle size of 150 nm to 500 nm. A charging roller characterized by containing black. The solubility parameter (SP value) of the conductive layer is 7.70 ≦ SP (cal ^1/2 / cm ^3/2 ) ≦ 8.70, and the hydrogen nucleus spin-spin relaxation time at a temperature of 30 ° C. and a relative humidity of 80% ( 2. The charging roller according to claim 1, wherein T2HH) is 40 ≦ T2HH (μs) ≦ 200.   The charging roller according to claim 1, wherein the vinyl content of the SBR is 10% by mass or more and 30% by mass or less.   4. The charging roller according to claim 1, wherein the carbon black is contained in an amount of 40 parts by mass to 100 parts by mass with respect to 100 parts by mass of the rubber.   5. The charging roller according to claim 1, wherein a surface layer containing polysiloxane having a fluorinated alkyl group and an oxyalkylene group is coated.   An electrophotographic photoreceptor having at least a photoconductive layer composed of an amorphous material mainly composed of silicon atoms, a charging means for charging the surface of the photoreceptor by a proximity or contact charging method, and exposing an image 2. An electrophotographic apparatus comprising: a latent image forming unit that forms a latent image; a developing unit that forms a toner image on a photoconductor; and a transfer unit that transfers a toner image to a transfer target. An electrophotographic apparatus using the charging roller according to claim 5.   At least an organic electrophotographic photosensitive member having a total surface protective layer and photosensitive layer thickness of 20 μm or less, charging means for charging the surface of the photosensitive member by proximity or contact charging, and exposing the image to form a latent image 6. An electrophotographic apparatus, comprising: a latent image forming unit that forms a toner image; a developing unit that forms a toner image on a photoconductor; and a transfer unit that transfers a toner image to a transfer target. An electrophotographic apparatus using the charging roller described in 1.