JP5173249B2 - Charging member, process cartridge, and electrophotographic image forming apparatus - Google Patents

Description

  The present invention relates to a charging member, an image forming apparatus using the charging member, a charging device, and a process cartridge. More specifically, the present invention relates to a charging member for applying a voltage to charge the surface of an electrophotographic photosensitive member, which is an object to be charged, to a predetermined potential, an image forming apparatus using the same, a charging device, and a process cartridge.

  A contact charging method has been put to practical use as a primary charging method for an electrophotographic image forming apparatus. This is intended for low ozone and low power, and in particular, a roller charging method using a conductive roller as a charging member is preferable and widely used in terms of charging stability.

  In the roller charging method, a conductive elastic roller is brought into pressure contact with a member to be charged, and a voltage is applied thereto to charge the member to be charged by discharge. Specifically, a DC voltage (DC voltage) obtained by adding a required photoreceptor surface potential Vd to a discharge start voltage (about 550 V when the charging roller is pressed against the OPC photoreceptor). There is a DC charging method in which charging is performed by applying (). Furthermore, there is an AC charging method for the purpose of improving potential fluctuations due to environmental and durability fluctuations. In the AC charging method, a voltage obtained by superimposing an AC component (AC component) having a peak-to-peak voltage more than twice the discharge start voltage on a DC voltage corresponding to the required photoreceptor surface potential Vd is applied to the contact charging member. To charge.

  The DC charging method has an advantage that the cost of the power supply is generally lower than that of the AC charging method. However, compared with the AC charging method, the DC charging method has a narrow discharge area and does not have the effect of leveling the AC discharge current, and therefore, streaky charging defects due to minute uneven resistance values of the charging member are likely to occur. There was a problem.

In view of this, a charging member used for the DC charging method has been proposed in which organic fine particles are contained in the surface layer of the charging member to form irregularities so as to improve streaky charging failure (Patent Document 1).
JP 2003-316112 A

  However, as disclosed in Patent Document 1, in the method in which organic fine particles are contained in the surface layer of the charging member and the unevenness is formed on the surface of the charging member, external additives and the like are easily deposited in the recesses, and accordingly, the charging capability of the recesses May be reduced.

  In recent years, with the demand for higher image quality in the market, the toner has become smaller in particle size and the proportion of toner fine particles has also increased. Furthermore, various external additives are also used with the high functionalization of the toner. Therefore, the degree of contamination of the charging member tends to increase. In addition, due to demands for longer life and color, the target durable life value of the unit including the charging member and the photosensitive member has been extended, and as a result, the amount of deposits has increased, which did not occur with the previous durable number. In some cases, image defects may become apparent in the latter half of the durability life. Particularly in a low-humidity environment, the charging ability was liable to be affected by the accumulation of dirt on the concave portion of the charging member. For this reason, the effect of improving the streaky charging failure due to the formation of the unevenness may be reduced, and the image quality may be deteriorated.

  Therefore, in the DC charging method, in order to achieve high image quality, colorization, and long life, they are one of the problems that must be solved.

  An object of the present invention is to solve the above-described problems and provide a charging member suitable for high image quality, colorization, and long life having excellent characteristics. Another object of the present invention is to provide an image forming apparatus, a charging device and a process cartridge using the charging member.

The present invention is a charging member for contact charging having a conductive substrate and a conductive surface layer,
The surface layer includes a binder resin and resin particles dispersed in the binder resin, and has a convex portion derived from the resin particle on the surface, and a ten-point average roughness Rzjis on the surface is 3 μm or more and 20 μm or less. And
The resin particles have an average particle diameter of 1 μm or more and 30 μm or less, and are composed of at least one selected from the group consisting of polyether ester, polyether amide, polyester amide, and polyether ester amide, and have conductivity. The present invention relates to a charging member.

Further, the present invention is a charging member for contact charging having a conductive substrate and a surface layer,
The surface layer includes a binder resin and resin particles dispersed in the binder resin, and has a convex portion derived from the resin particle on the surface, and a ten-point average roughness Rzjis on the surface is 3 μm or more and 20 μm or less. And
The resin particles have an average particle diameter of 1 μm or more and 30 μm or less, include a polymer having at least one selected from the structures of the following formulas (1) and (2) as a repeating structural unit, and have conductivity. The present invention relates to a charging member.

_{- (CH 2 CH 2 O)} - (1)
_{- (CH (CH 3) CH} 2 O) - (2)
Further, according to the present invention, the charging member and the member to be charged are at least integrated, and the convex portion of the surface layer of the charging member generates a gap in the nip portion with the member to be charged, so that the electrophotographic image forming apparatus The present invention relates to a process cartridge which is detachable from a main body.

  The present invention further relates to an electrophotographic image forming apparatus comprising at least the process cartridge, an exposure unit, and a development unit.

  According to the present invention, it is possible to provide a charging member capable of stably maintaining good charging characteristics for a long period of time even when a high-definition image such as a halftone image of 600 dpi is output by a DC charging method. it can. Furthermore, by using the charging member of the present invention, even when a high-definition image is output by the DC charging method, an image forming apparatus having a charging member that can stably maintain good charging characteristics for a long period of time, A charging method and a process cartridge can be provided.

  As a result of intensive studies, the inventors have found that it is effective to contain conductive resin particles in the surface layer as a roughening agent for forming convex portions on the surface of the charging member. I understood that.

  The present inventors consider the action of resin particles having conductivity as a roughening agent for forming a convex portion as follows.

  First, an investigation was made as to why streaky charging defects would be improved if convex portions were formed on the surface of the charging member. Therefore, for the purpose of analyzing the streaky charging failure in the DC charging method, we tried to evaluate it by observing the discharge state (drum surface potential) of the charging member. As a result, it was confirmed that in the charging member in which the convex portion is formed by the resin particles, discharge occurs in the nip in addition to the discharge on both sides of the nip portion with the photoreceptor. However, with a smooth surface charging member that does not contain resin particles, discharge was only in the gaps on both sides of the nip with the photoreceptor, and no discharge was observed in the nip (conceptual diagram: FIG. 7).

  From this result, by including resin particles in the surface layer of the charging member, minute convex portions are formed on the surface of the charging member. When the charging member having these convex portions is used as a charging member for contact charging, it is considered that a small gap is formed in the nip portion with the photosensitive member as a charged body to cause discharge (conceptual diagram: FIG. 8). ). That is, it is considered that the streaky charging failure generated in the gap on the upstream side of the nip portion has an action of leveling by the discharge in the nip.

  Next, the phenomenon in which streaky charging defects occur in the latter half of the endurance life of the charging member having irregularities on the surface was considered as follows.

  As described above, in the method of forming irregularities on the surface of the charging member, it is considered that external additives or the like are easily deposited in the concave portions, and the charging ability of the concave portions is reduced due to the influence (conceptual diagram: FIG. 9). . However, as a roughening agent for forming convex portions on the surface of the charging member, if conductive resin particles are contained in the surface layer, for example, external additives are deposited in the concave portions, and the charging ability of the concave portions is reduced. However, the discharge can be maintained from the slope of the convex portion. Therefore, it is considered that it is effective in improving the streaky charging failure in the latter half of the endurance life (conceptual diagram: FIG. 10).

  By using such a charging member, it is possible to suppress the occurrence of charging defects due to dirt and streak-like charging defects due to a decrease in charging ability even after repeated use over a long period of time. Furthermore, it is possible to suppress the occurrence of a stain unevenness image and a stripe-like unevenness image (charged horizontal streak image).

  The charging member can be used in a DC charging method in which demands for unevenness in electrical resistance are severe, and is excellent in durability.

(Resin particles of the first embodiment)
The resin particles of the first embodiment are characterized by a configuration comprising at least one selected from the group consisting of polyether ester, polyether amide, polyester amide, and polyether ester amide.

  The polyether ester refers to a copolymer having a hard segment made of polyester and a soft segment made of polyether. For example, it is a copolymer obtained by reacting a polyalkylene oxide glycol component, a dicarboxylic acid component, and a diol component.

  The polyether ester can be produced by a generally known production method. For example, it can be manufactured by a method of directly esterifying three groups of polyalkylene oxide glycol, dicarboxylic acid, and aliphatic diol, or a method in which polycarboxylic acid oxide glycol is added and polycondensed after transesterification of dicarboxylic acid and aliphatic diol. sell.

  The polyalkylene oxide glycol component is illustrated. Poly (alkylene oxide) glycols include polyethylene glycol, poly (1,2-propylene oxide) glycol, poly (1,3-propylene oxide) glycol, poly (tetramethylene oxide) glycol, poly (hexamethylene oxide) glycol, A block or random copolymer of ethylene oxide and propylene oxide, a block or random copolymer of ethylene oxide and tetrahydrofuran, or the like is used.

  Examples of the polyalkylene oxide glycol component include alkylene oxide adducts of bisphenols. Specific examples of bisphenols constituting the alkylene oxide adduct of bisphenols include bisphenol A, bisphenol S, brominated bisphenol A, 4,4-bis (hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfoxide, bis ( 4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) amine. Bisphenol A is preferable. Examples of the alkylene oxide constituting the alkylene oxide adduct of bisphenols include ethylene oxide (EO) and / or propylene oxide (PO). When EO and PO are used in combination, random addition or block addition may be used.

  The dicarboxylic acid component is illustrated. Specific examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, 4,4′-diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid and 5 An aromatic dicarboxylic acid such as sodium sulfoisophthalic acid; 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3- Cycloaliphatic dicarboxylic acids such as dicarboxymethylcyclohexane, 1,4-dicarboxymethylcyclohexane and dicyclohexyl-4,4′-dicarboxylic acid; succinic acid, oxalic acid, adipic acid, sebacic acid and dodecanedioic acid (decanedicarboxylic acid) Aliphatic dicarboxylic acids such as Comprising a mixture of these.

  The diol component is illustrated. Specific examples of the diol include ethylene glycol, propylene glycol, 1,4-butanediol, neoventyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, cyclohexanedimethanol, and the like. -12 aliphatic or alicyclic diols; bisphenols such as bis (p-hydroxy) diphenyl, bis (p-hydroxyphenyl) methane, bis (p-hydroxyphenyl) propane; and mixtures thereof.

  The polyether amide refers to a copolymer having a hard segment made of polyamide and a soft segment made of polyether. For example, it is a copolymer obtained by reacting a diamine component and the dicarboxylic acid component with a diamine-modified end of the polyalkylene oxide glycol component. The polyether amide can be produced by a generally known production method.

  The diamine component is illustrated. Examples of the diamine include ethylene diamine, tetramethylene diamine, hexamethylene diamine, and phenylene diamine. Furthermore, as the diamine component, it is also possible to use a polyethylene glycol diamine having both ends modified with amino groups by reacting polyalkylene oxide glycol with acrylonitrile and further carrying out a hydrogenation reaction.

  These diamines use salts formed with the dicarboxylic acid component described above, and salts of diamine-dicarboxylic acids such as hexamethylenediamine-adipate, hexamethylenediamine-sebacate, and hexamethylenediamine-isophthalate. You can also.

  Lactam, α, ω-aminocarboxylic acid can also be used as a raw material having the same effect as that of obtaining a polyamide obtained from diamine and dicarboxylic acid. Specifically, aminocarboxylic acids such as ω-aminocaproic acid, ω-aminoenanthic acid, ω-aminocaprylic acid, ω-aminopergonic acid, ω-aminocapric acid, 11-aminoundecanoic acid, 12-aminododecanoic acid; Lactams such as caprolactam, enantolactam, capryllactam and laurolactam.

  Polyesteramide refers to a copolymer having a segment made of polyester and a segment made of polyamide. For example, it is a copolymer obtained by reacting the dicarboxylic acid component, the diol component, and the diamine component. Polyesteramide can be produced by a generally known production method.

  A conventionally known polyether ester amide can be applied to the polyether ester amide. For example, it is a copolymer obtained by reacting the polyalkylene oxide glycol component, the diamine component, and the dicarboxylic acid component. It does not specifically limit regarding the manufacturing method of polyetheresteramide, Usually, it can manufacture according to a well-known manufacturing method. For example, it is produced by polycondensation using a polyamide-forming monomer, a hydroxyl-terminated polyether and a dicarboxylic acid as starting materials.

  In the polymerization for obtaining polyether ester, polyether amide, polyester amide, polyether ester amide, a catalyst may be used as necessary. There is no restriction | limiting in particular about the catalyst to be used. Specific examples of catalysts include antimony catalysts (such as antimony trioxide), tin catalysts (such as monobutyltin oxide), titanium catalysts (such as tetrabutyl titanate), zirconium catalysts (such as tetrabutylzirconate), metal acetate Includes salt systems (such as zinc acetate). Moreover, you may use antioxidant at the time of superposition | polymerization as needed. Furthermore, various stabilizers, modifiers, pigments and the like can be used as necessary.

  The polyether ester amide, polyester amide, polyether amide, and polyether ester are commercially available from the following manufacturers under the following trade names. For example, Toyobo's Perprene (trade name), Sanyo Kasei Kogyo's Pelestat (trade name), Atofina's Pebax (trade name), Fuji Kasei's TPAE series (trade name), Toray DuPont's Hytrel (trade name) Product name).

  When the above-mentioned polyether ester amide, polyester amide, polyether amide, or polyether ester is used to impart conductivity to the resin particles, it is possible to impart conductivity evenly and in the middle resistance region, realizing stable uniform discharge. Presumed to be possible. Furthermore, it is preferable because conductivity is stably expressed even with respect to environmental changes in temperature and humidity. Resin particles made of a polymer compound as a roughening agent are preferable because they have elasticity and are less likely to damage a photosensitive drum as a charged body than inorganic fine particles.

  An example is shown about the manufacturing method of the resin particle of 1st embodiment.

  The pelletized polyether ester amide, polyester amide, polyether amide, polyether ester is pulverized by a known method (mechanical pulverization, freeze pulverization, etc.), and classified as necessary to obtain desired resin particles. .

  Moreover, the following methods are mentioned as a method of obtaining the resin particle more nearly spherical. Polyether ester amide, polyester amide, polyether amide, polyether ester (referred to as Resin A) is mixed with another resin that is not compatible with Resin A (referred to as Resin B), and Resin A and Resin Mix and disperse B uniformly. Thereafter, the mixture is cooled to a temperature equal to or lower than the melting point, and a developing solvent which is incompatible with resin A but is compatible with resin B and the resin mixture are mixed to obtain a suspension of resin particles. And the particle | grains which consist of resin A can be obtained by isolate | separating this by centrifuging, filtration, or combining these methods. Examples of the resin B include polyethylene oxide, polyethylene glycol, polyvinyl alcohol, and the like, and these can be used alone or in combination.

  The average particle diameter of the resin particles of the first embodiment is controlled to 1 μm or more and 30 μm or less, and preferably 3 μm or more and 15 μm or less. If the average particle diameter of the resin particles of the first embodiment exceeds 30 μm, the charging roller surface becomes too rough and charging becomes non-uniform, or the amount of toner and external additives deposited in the recesses increases. is there. In addition, if the average particle diameter of the resin particles of the first embodiment is less than 1 μm, it is not preferable because even if the resin particles are added, the effect of stabilizing the charging does not appear because the discharge does not easily occur in the nip.

  In addition, the entire resin particles have uniform conductivity, and generation of a potty image due to resistance unevenness or an image due to pinhole leakage can be suppressed. In addition, bleed-out such as low molecular weight components from the resin particles can be suppressed. That is, it is possible to suppress the occurrence of an image caused by dirt, an image caused by defective discharge, a charged horizontal streak image, a charged unevenness image, or a spot image even when used repeatedly for a long period of time.

  Here, the specific example of the particle diameter measurement of the resin particle of 1st embodiment is shown.

  First, when measuring resin particles as powder, it can be measured using a Coulter counter multisizer or the like. 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 (resin particles) is added thereto. The electrolyte solution in which the sample is suspended is dispersed for 1 to 3 minutes using an ultrasonic disperser, and an aperture adjusted to an appropriate resin particle size such as 17 μm or 100 μm using a Coulter counter multisizer is used as a reference based on volume. The particle size distribution of 3 to 64 μm is measured. The mass average particle diameter measured under these conditions is determined by computer processing.

  The particle diameter of the resin particles contained in the surface layer can also be easily determined by observing the cross section of the layer with a microscope or the like. For example, the surface layer of the conductive roller is thinly sliced with a razor or the like so that the cross section can be observed. FIG.3 (c) shows the schematic diagram of a cut cross section. The average particle diameter of the resin particles was determined by observing only 100 primary particles excluding the secondary agglomerated particles with a transmission electron microscope (TEM), obtaining the projected area, and calculating the equivalent circle diameter of the obtained area. The volume average particle diameter can be obtained by calculation, and it can be obtained as the average particle diameter.

  About the resin particle of 1st embodiment, the addition amount is 1 mass% or more and 80 mass% or less as a mass ratio in the surface layer after coating, and 5 mass% or more and 70 mass% or less are more preferable. If the amount is too small, the effect of stabilizing the charge by adding resin particles may not be obtained. If the amount is too large, it takes time to control the viscosity of the surface layer coating material.

The resin particles of the first embodiment have conductivity. The volume resistivity of the resin particles of the first embodiment is preferably 1 × 10 ⁶ Ω · cm to 1 × 10 ¹⁰ Ω · cm. More preferably, it is 1 × 10 ⁷ Ω · cm or more and 1 × 10 ⁹ Ω · cm. When the volume resistivity of the resin particles of the first embodiment is lower than 1 × 10 ⁶ Ω · cm, the resistance uniformity of the resin particles may not be obtained. For example, in a high-temperature and high-humidity environment, the resin An image due to overdischarge, which is estimated to be caused by a part of the low resistance part of the particle, may occur. When the volume resistivity of the resin particles of the first embodiment is higher than 1 × 10 ¹⁰ Ω · cm, the induction of discharge is suppressed. For example, in the case where image creation is performed at high speed, Control can be disadvantageous.

  The measuring method of the volume resistivity of the resin particles of the first embodiment is as follows.

  The volume resistivity is measured in an environment of 23 ° C. and 55% Rh normal pressure. Measurement is performed with electrodes in which cylindrical electrodes made of stainless steel (made of SUS316) are arranged above and below a cylinder made of polytetrafluoroethylene (PTFE) having an inner diameter of 1 cm. The measurement sample and the electrode are measured after being left in the above environment for 12 hours or longer and accustomed to the environment.

  A lower electrode made of SUS is arranged at the lower part of the PTFE cylinder, about 2 g of resin particles are put so as not to be offset, a SUS cylindrical electrode is placed from above, and sandwiched between the PTFE cylinder and the upper and lower electrodes. The sample is allowed to stand for 1 minute or more with a pressure of 10 MPa applied. Thereafter, a voltage of 200 V is applied using a microammeter (trade name: ADVANTEST R8340A ULTRA HIGH RESISTANCE METER, manufactured by Advantest Corporation). Then, the current after 30 seconds is measured and calculated from the distance between the electrode surfaces and the electrode area.

(Resin particles of the second embodiment)
The resin particles of the second embodiment are characterized by a structure comprising a polymer having at least one selected from the structures of the following formulas (1) and (2) as a repeating structural unit.

_{- (CH 2 CH 2 O)} - (1)
_{- (CH (CH 3) CH} 2 O) - (2)
As said polymer contained in the resin particle of 2nd embodiment, the following are mentioned, for example. Ethylene oxide homopolymer, propylene oxide homopolymer, copolymer of ethylene oxide and propylene oxide, or copolymer of epichlorohydrin and ethylene oxide, ternary copolymer of epichlorohydrin, ethylene oxide and allyl glycidyl ether Polymer, terpolymer of ethylene oxide, propylene oxide and allyl glycidyl ether.

  The resin particles of the second embodiment may be composed only of a polymer having at least one selected from the structures of the formulas (1) and (2) as a repeating structural unit, but the conductive particles containing other polymers May be composed of a conductive polymer composition. Examples of other polymers include polyvinyl alcohol, polyvinyl acetate, ethylene vinyl acetate copolymer, polymethyl methacrylate, polystyrene, and polyvinyl butyral. The polymer composition in the conductive polymer composition can be selected so that the resin particles of the second embodiment exhibit desired conductivity. Usually, the proportion of the polymer having at least one selected from the structures of formulas (1) and (2) as a repeating structural unit is preferably 50% by mass or more and 100% by mass or less, and more preferably 60% by mass or more and 100% by mass or less. preferable.

  When conductivity is imparted to the resin particles using the polymer as described above, it is presumed that the conductivity can be imparted uniformly and in the middle resistance region, and stable uniform discharge can be realized. Furthermore, it is preferable because stable electric characteristics (ionic conductivity) can be maintained even when energized for a long time. Resin particles made of a polymer compound as a roughening agent are preferable because they have elasticity and are less likely to damage a photosensitive drum as a charged body than inorganic fine particles.

  A known method can be used as a method for producing the resin particles containing the conductive polymer of the second embodiment, and is not particularly limited. For example, it can be produced by mechanical pulverization or freeze pulverization of the conductive polymer composition.

  The average particle diameter of the resin particles of the second embodiment is controlled to 1 μm or more and 30 μm or less, and preferably 3 μm or more and 15 μm or less. If the average particle diameter of the resin particles of the second embodiment exceeds 30 μm, the charging roller surface becomes too rough and charging becomes non-uniform, or the amount of toner and external additives deposited in the recesses increases. is there. Further, if the average particle diameter of the resin particles of the second embodiment is less than 1 μm, even if the resin particles are added, since it is difficult for discharge to occur in the nip, the effect of stabilizing the charging does not appear, which is not preferable.

  Here, the specific example of the particle diameter measurement of the resin particle of 2nd embodiment is shown.

  First, when measuring resin particles as powder, it can be measured using a Coulter counter multisizer or the like. 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 (resin particles) is added thereto. The electrolyte solution in which the sample is suspended is dispersed for 1 to 3 minutes using an ultrasonic disperser, and an aperture adjusted to an appropriate resin particle size such as 17 μm or 100 μm using a Coulter counter multisizer is used as a reference based on volume. The particle size distribution of 3 to 64 μm is measured. The mass average particle diameter measured under these conditions is determined by computer processing.

  The particle diameter of the resin particles contained in the surface layer can also be easily determined by observing the cross section of the layer with a microscope or the like. For example, the surface layer of the conductive roller is thinly sliced with a razor or the like so that the cross section can be observed. FIG. 3C shows a schematic diagram of a cut section. The average particle diameter of the resin particles was determined by observing only 100 primary particles excluding the secondary agglomerated particles with a transmission electron microscope (TEM), obtaining the projected area, and calculating the equivalent circle diameter of the obtained area. The volume average particle diameter can be obtained by calculation, and it can be obtained as the average particle diameter.

  About the resin particle of 2nd embodiment, the addition amount is 1 mass% or more and 80 mass% or less as a mass ratio in the surface layer after coating, and 5 mass% or more and 70 mass% or less are more preferable. If the amount is too small, the effect of stabilizing the charge by adding resin particles may not be obtained. If the amount is too large, it takes time to control the viscosity of the surface layer coating material.

The resin particles of the second embodiment have conductivity. The volume resistivity of the resin particles of the second embodiment is preferably 1 × 10 ⁶ Ω · cm or more and 1 × 10 ¹⁰ Ω · cm or less. More preferably, it is 1 × 10 ⁷ Ω · cm or more and 1 × 10 ⁹ Ω · cm. When the volume resistivity of the resin particles of the second embodiment is lower than 1 × 10 ⁶ Ω · cm, the resistance uniformity of the resin particles may not be obtained. For example, in a high-temperature and high-humidity environment, the resin An image due to overdischarge, which is estimated to be caused by a part of the low resistance part of the particle, may occur. When the volume resistivity of the resin particles of the second embodiment is higher than 1 × 10 ¹⁰ Ω · cm, the induction of discharge is suppressed. For example, in the case where image creation is performed at high speed, Control can be disadvantageous.

  The measuring method of the volume resistivity of the resin particles of the first embodiment is as follows.

  The volume resistivity is measured in an environment of 23 ° C. and 55% Rh normal pressure. Measurement is performed with electrodes in which cylindrical electrodes made of stainless steel (made of SUS316) are arranged above and below a cylinder made of polytetrafluoroethylene (PTFE) having an inner diameter of 1 cm. The measurement sample and the electrode are measured after being left in the above environment for 12 hours or longer and accustomed to the environment.

  A lower electrode made of SUS is arranged at the lower part of the PTFE cylinder, about 2 g of resin particles are put so as not to be offset, a SUS cylindrical electrode is placed from above, and sandwiched between the PTFE cylinder and the upper and lower electrodes. The sample is allowed to stand for 1 minute or more with a pressure of 10 MPa applied. Thereafter, a voltage of 200 V is applied using a microammeter (trade name: ADVANTEST R8340A ULTRA HIGH RESISTANCE METER, manufactured by Advantest Corporation). Then, the current after 30 seconds is measured and calculated from the distance between the electrode surfaces and the electrode area.

  Next, the charging member, the image forming apparatus using the charging member, the charging method and the process cartridge of the present invention will be described in detail.

<1> Charging Member A specific configuration of the charging member of the present invention is shown in FIG. FIG. 1A shows a transverse section of the charging member, and FIG. 1B shows a longitudinal section.

(1) Conductive Substrate The charging member of the present invention includes a conductive support 1, a conductive elastic layer 2 formed on the outer periphery thereof, and a surface layer 3 covering the outer periphery of the conductive elastic layer 2. It is a member. In this case, the conductive support 1 and the conductive elastic layer 2 are collectively referred to as a conductive substrate.

  As the conductive support 1, for example, a cylinder having a nickel plating with a thickness of 5 μm on the surface of a carbon steel alloy can be used. The following are mentioned as another material which comprises an electroconductive support body. Metals such as iron, aluminum, titanium, copper and nickel; alloys such as stainless steel, duralumin, brass and bronze containing these metals; composite materials in which carbon black and carbon fibers are consolidated with plastic. It is also possible to use a known material that is rigid and exhibits conductivity. Moreover, as a shape, it can also be set as the cylindrical shape which made the center part the cavity other than column shape.

  In the present invention, preferably, the conductive elastic layer 2 is formed on the outer periphery of the conductive support 1. The conductive elastic layer 2 is made of a conductive elastic body. The conductive elastic body is formed by mixing a conductive agent and a polymer elastic body.

  Examples of the polymer elastic body include the following. Epichlorohydrin rubber, NBR (nitrile rubber), chloroprene rubber, urethane rubber, silicone rubber, or thermoplastic elastomer such as SBS (styrene / butadiene / styrene / block copolymer), SEBS (styrene / ethylene butylene / styrene / block copolymer).

  As the polymer elastic body, epichlorohydrin rubber is particularly preferably used. In the epichlorohydrin rubber, the polymer itself has conductivity in the middle resistance region, and can exhibit good conductivity even if the amount of the conductive agent added is small. Moreover, since the variation in electric resistance depending on the position can be reduced, it is suitably used as a polymer elastic body. Examples of the epichlorohydrin rubber include the following. Epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-allyl glycidyl ether copolymer and epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer. Of these, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer is particularly preferably used since it exhibits stable conductivity in a medium resistance region. The epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer can control conductivity and workability by arbitrarily adjusting the degree of polymerization and composition ratio.

  The polymer elastic body may be epichlorohydrin rubber alone, but it may contain epichlorohydrin rubber as a main component and other general rubber as necessary. Other common rubbers include the following. Examples thereof include EPM (ethylene / propylene rubber), EPDM (ethylene / propylene rubber), NBR (nitrile rubber), chloroprene rubber, natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, urethane rubber, and silicone rubber. Further, a thermoplastic elastomer such as SBS (styrene / butadiene / styrene block copolymer) or SEBS (styrene / ethylene butylene / styrene block copolymer) may be contained. When it contains said general rubber, it is preferable that the content is 1-50 mass% with respect to the polymer elastic body whole quantity.

  As the conductive agent, an ionic conductive agent or an electronic conductive agent can be used. For the purpose of reducing unevenness in electrical resistivity of the conductive elastic layer, it is preferable to contain an ionic conductive agent. By uniformly dispersing the ionic conductive agent in the polymer elastic body and making the electrical resistance of the conductive elastic body uniform, uniform charging can be obtained even when the charging roller is used with only DC voltage applied. Can do.

  The ionic conductive agent is not particularly limited as long as it is an ionic conductive agent exhibiting ionic 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.

  The electronic conductive agent is not particularly limited as long as it is an electronic conductive agent exhibiting electronic conductivity. Examples of the electronic conductive agent include the following. Metal-based powders and fibers such as aluminum, palladium, iron, copper and silver; metal oxides such as titanium oxide, tin oxide and zinc oxide; tin oxide, antimony oxide, indium oxide and molybdenum oxide on the surface of suitable particles , Zinc, aluminum, gold, silver, copper, chromium, cobalt, iron, lead, platinum, or rhodium powder deposited by electrolytic treatment, spray coating, mixed shaking; furnace black, thermal black, acetylene black, Carbon powder such as 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.

As the blending amount of the conductive agent to be blended with the conductive elastic body of the present invention, the volume resistivity of the conductive elastic body is a medium resistance region (volume) in all of the low temperature and low humidity environment, the normal temperature and normal humidity environment, and the high temperature and high humidity environment. It is preferable to determine the resistivity to be 1 × 10 ⁴ to 1 × 10 ⁸ Ω · cm. The low temperature and low humidity environment is 15 ° C./10% RH (environment 1), the normal temperature and normal humidity environment is 23 ° C./50% RH (environment 2), and the high temperature and high humidity environment is 30 ° C./80% RH (environment 3). ).

  If the volume resistivity of the conductive elastic body is smaller than this, if there is a pinhole in the photosensitive member as the member to be charged, a large current will be concentrated in the pinhole at a stretch, and the applied voltage will drop, resulting in high definition. There is a tendency that a portion having a belt-like shape and insufficient charging potential appears on a halftone image. Moreover, there is a possibility that a problem such as making the pinhole larger will occur. Conversely, if the volume resistivity is too large, a high voltage must be applied in order to obtain a desired charging potential.

  The volume resistivity of the conductive elastic body is determined as follows. First, after forming into a sheet having a thickness of 1 mm, a metal is vapor-deposited on both surfaces to produce an electrode and a guard electrode. Next, a voltage of 200 V is applied using a microammeter (trade name: ADVANTEST R8340A ULTRA HIGH RESISTANCE METER, manufactured by Advantest Corporation). Then, the current after 30 seconds is measured and calculated from the film thickness and the electrode area.

  In addition, plasticizers, fillers, vulcanizing agents, vulcanization accelerators, anti-aging agents, scorch preventing agents, dispersants and release agents may be added to the conductive elastic body as necessary. You can also.

  As a method for forming the conductive elastic body, it is preferable to mix the raw materials of the above-described conductive elastic body with a hermetic mixer and form the conductive elastic body by a known method such as extrusion molding, injection molding, or compression molding. The conductive elastic layer may be produced by directly forming a conductive elastic body on a conductive support, or a conductive elastic body previously formed into a tube shape is coated on the conductive support. You may let them. Note that the surface may be polished and the shape may be adjusted after the production of the conductive elastic layer.

  The shape of the conductive elastic layer is preferably formed in a crown shape in which the central portion is thickest and narrows toward both ends in order to ensure uniform adhesion between the charging roller and the electrophotographic photosensitive member. Since a charging roller that is generally used applies a predetermined pressing force to both ends of the support and is in contact with the electrophotographic photosensitive member, the pressing force at the center is small and increases at both ends. Therefore, there is no problem if the straightness of the charging roller is sufficient, but if it is not sufficient, density unevenness may occur in the images corresponding to the center and both ends. The crown shape is formed to prevent this.

  In addition, since the contact nip width during rotation of the roller is uniform, it is preferable that the outer diameter difference of the roller (conductive elastic base layer roller) on which the conductive elastic layer is formed is small.

  As shown in FIG. 2, the measured value of run-out is obtained by rotating the conductive elastic base layer roller about the conductive support as a rotation axis, and measuring with a non-contact laser length meter perpendicular to the rotation axis. The difference between the maximum value and the minimum value of the radius is obtained as a value. In the present invention, LS-5000 (trade name) manufactured by Keyence Corporation is used as a non-contact laser length measuring device. The difference between the maximum value and the minimum value of the radius is obtained at a pitch of 1 cm in the axial direction of the conductive elastic base layer roller, and the maximum value among the values (maximum values) is determined as the deflection value of the conductive elastic base layer roller. And

  A preferable value of the deflection of the conductive elastic base layer roller is 0.5% or less, more preferably 0.25% or less, of the diameter of the central portion of the roller. For example, when the diameter of the roller is about 12 mm, the value of runout is specifically preferably 60 μm or less, more preferably 30 μm or less.

  Similarly, the diameter of the roller is the maximum of the diameter of the conductive elastic layer measured by a non-contact laser length measuring device perpendicularly to the rotation axis by rotating the conductive elastic base layer roller about the conductive support as the rotation axis. The average of the value and the minimum value. For example, in the case of a roller of about 250 mm in the axial direction, the diameter D1 of the central portion in the axial direction of the conductive elastic base layer roller and the average of two values of the diameters D2 and D3 of the portion on the end side of 90 mm from the central portion in the axial direction The difference {D1− (D2 + D3) / 2} is obtained as a value of the crown amount.

  The value of the crown amount is determined so that the nip width of the finished roller is uniform, but is preferably 5.0% or less of the roller diameter. Specifically, when the diameter is about 12 mm, 600 μm or less is preferable.

  The hardness of the conductive elastic body 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 member and the photosensitive member becomes small, and the contact force between the charging member and the photosensitive member concentrates in a small area, and the contact Pressure increases. This may cause adverse effects such as charging becoming unstable or developer or the like being easily attached to the surface of the photoreceptor or charging member.

  In addition, "micro hardness (MD-1 type)" is the hardness of the charging member 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 peak hold mode of 10 N with respect to a charging member left for 12 hours or more in an environment of normal temperature and normal humidity (23 ° C./55% RH).

  For the purpose of reducing the micro hardness (MD-1 type), a plasticizer may be added to the conductive elastic body. The compounding amount of the plasticizer is preferably 1 part by mass to 30 parts by mass, and more preferably 3 parts by mass to 20 parts by mass. As the plasticizer, it is preferable to use a polymer type. The molecular weight of the polymer plasticizer is preferably 2000 or more, more preferably 4000 or more. If the molecular weight is less than 2000, the plasticizer may ooze out on the surface of the roller and contaminate the photoreceptor.

  The conductive elastic layer is bonded to the conductive support through an adhesive as necessary. 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 a resin such as a thermosetting resin or a thermoplastic resin. Known adhesives such as urethane, acrylic, polyester, polyether and epoxy can be used. What was mentioned above can be used as a electrically conductive agent for providing electroconductivity to an adhesive agent. The conductive agents can be used alone or in combination of two or more.

  After producing the conductive elastic layer, the surface layer 3 is provided as the covering layer.

(2) Surface layer The surface layer includes a binder resin and the resin particles of the first or second embodiment, and the resin particles of the first or second embodiment are dispersed in the binder resin. . The addition amount of the resin particles of the first or second embodiment is as described above.

  As the binder resin for the surface layer, a resin such as a thermosetting resin or a thermoplastic resin is used. Examples of the binder resin for the surface layer of the present invention include urethane resins, fluorine resins, silicone resins, acrylic resins, and polyamide resins. Among these, a urethane resin obtained by crosslinking a lactone-modified acrylic polyol with an isocyanate is particularly preferably used.

  The lactone-modified acrylic polyol is a copolymer of styrene and acrylic in the molecular chain skeleton, and has an appropriate hardness and non-contaminating property. In addition, a modified lactone group having a hydroxyl group at the terminal serves as a number of cross-linking points and can be cross-linked tightly with an isocyanate, thereby preventing the low molecular component from oozing out from the conductive elastic layer. The OH value of the lactone-modified acrylic polyol is preferably about 70 to 90 KOHmg / g. When the OH value is small, it is difficult to crosslink with isocyanate, and thereby the resin becomes too soft and easily sticks to the photoreceptor. If the OH group is too large, the coating film becomes too hard and easily breaks when subjected to an impact.

  It is more preferable to use an isocyanurate type trimer as the isocyanate. The rigid trimer of the molecule becomes a cross-linking point, the surface layer can be cross-linked more densely, and the exuding substance of low molecular components from the conductive elastic layer is further exuded on the roller surface. Can be prevented. The isocyanate is more preferably a blocked isocyanate in which an isocyanate group is blocked with a blocking agent. The reason for this is that the isocyanate group is easy to react, and when the coating material for surface layer coating is allowed to stand at room temperature for a long time, the reaction gradually proceeds and the properties of the coating material may change. On the other hand, the blocked isocyanate has an advantage that the active isocyanate group is blocked and does not react up to the dissociation temperature of the blocking agent, so that the paint can be easily handled. Examples of the blocking agent for performing masking include phenols such as phenol and cresol, lactams of ε-caprolactam, and oximes such as methyl ethyl ketoxime. In the present invention, oximes having a relatively low dissociation temperature are preferable. .

  The blend ratio of the lactone-modified acrylic polyol resin and the isocyanate is the ratio of the number of NCO groups (A) of the isocyanate in the blended paint and the number of OH groups (B) of the lactone-modified acrylic polyol resin (NCO / OH = A / B) is preferably 0.1 to 2.0. Particularly preferably, the A / B is adjusted to be in the range of 0.3 to 1.5.

  By cross-linking lactone-modified acrylic polyol with isocyanate, the low molecular weight component is prevented from seeping out from the conductive elastic layer, and the charging roller itself is not easily contaminated with toner and external additives, and the photoreceptor is contaminated. A surface layer can be formed.

  In addition, the surface layer can contain a conductive agent. As the conductive agent, the above-described ionic conductive agent, electronic conductive agent, or the like can be used. When a conductive agent is used for the surface layer, a material that is not easily affected by external factors such as the environment is preferable. Therefore, generally an electronic conductive agent is often used.

  As the conductive agent, it is preferable to use conductive fine particles having a primary particle diameter of 0.01 μm or more and 0.9 μm or less by observation using a differential scanning electron microscope.

The amount of the conductive agent added to the binder resin of the surface layer is such that the volume resistivity of the surface layer is low / low humidity environment, normal temperature / humidity environment, high temperature / humidity environment. X10 ⁶ to 1 × 10 ¹⁵ Ω · cm) is preferable. The low temperature and low humidity environment is 15 ° C./10% RH (environment 1), the normal temperature and normal humidity environment is 23 ° C./50% RH (environment 2), and the high temperature and high humidity environment is 30 ° C./80% RH (environment 3). ).

  When the volume resistivity of the surface layer is smaller than this, when used as a charging roller, an excessive current flows through the pinhole when the photoconductor has a pinhole, and the applied voltage drops. There are cases where the entire longitudinal direction appears in the image as a belt-like charging defect. On the other hand, if the volume resistivity is too large, it is difficult for current to flow through the charging roller, and the photosensitive member cannot be charged to a predetermined potential, and an adverse effect that an image does not have a desired density may occur. Further, even if charged to a certain potential, the charging ability is low, so that a ghost image or other adverse effects may appear.

  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. A voltage of 200 V is applied to the obtained measurement sample using a microammeter (trade name: ADVANTEST R8340A ULTRA HIGH RESISTANCE METER, manufactured by Advantest Corporation). Then, the current after 30 seconds is measured and calculated from the film thickness and the electrode area.

  As addition amount of a electrically conductive agent, 2 to 80 mass% is preferable with respect to the surface layer after coating, Most preferably, it is 20 to 60 mass%.

  The surface of the conductive agent used in the present invention may be surface-treated with a coupling agent. The coupling agent is a compound having a hydrolyzable group and a hydrophobic group in the same molecule and bonded to a central element such as silicon, aluminum, titanium or zirconium, and a long chain alkyl group in this hydrophobic group part. It is what has.

  As the hydrolyzable group, for example, alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group having relatively high hydrophilicity are used. In addition, an acryloxy group, a methacryloxy group, modified products thereof, and halogen are also used. The hydrophobic group only needs to include a structure in which six or more carbon atoms are connected in a straight chain in the structure, and in the bonding form with the central element, carboxylate ester, alkoxy, sulfonate ester or phosphoric acid. It may be bonded via an ester or directly. Furthermore, a functional group such as an ether bond, an epoxy group and an amino group may be included in the structure of the hydrophobic group. By treating the coupling agent, adsorption of moisture on the surface of the conductive agent can be suppressed, and a surface layer material with less environmental fluctuation can be obtained. As the coupling agent used in the present invention, a highly reactive silane coupling agent is preferable.

  The following are mentioned as a silane coupling agent. Hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, trifluoropropyltrimethoxysilane and hexyltrimethoxysilane.

  Insulating inorganic particles may be added to the surface layer. The inorganic particles preferably contain silica and titanium oxide. The inorganic particles are preferably fine particles having a primary particle size of 0.5 μm or less.

Furthermore, a fine powder such as silica or titanium oxide that has been surface-treated may be used. The surface treatment is applied by chemical treatment with an organosilicon compound that reacts or physically adsorbs with silica fine powder or titanium oxide fine powder. Preferred methods include the following.
A method of treating dry silica fine powder produced by vapor phase oxidation of a silicon halogen compound with a silane coupling agent.
A method of treating with an organosilicon compound such as silicone oil.
A method of treating with an organosilicon compound such as silicone oil after treating with a silane coupling agent or simultaneously with treating with a silane coupling agent.

  The following are mentioned as a silane coupling agent used for surface treatment. Hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloro Ethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyl Disiloxane, 1,3-divinyltetramethyldisiloxane and 1,3-diphenyltetramethyl Disiloxane.

  Examples of the organosilicon compound used for the surface treatment include silicone oils. Preferred silicone oils are those having a viscosity at 25 ° C. of about 30 to 1,000 centistokes. For example, it is preferable to use dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil or fluorine modified silicone oil.

  As a surface treatment method using silicone oil, for example, silica fine powder treated with a silane coupling agent and silicone oil may be directly mixed using a mixer such as a Henschel mixer. Alternatively, a method of injecting the silicone differential oil to the base silica derivative may be used. Alternatively, the surface treatment may be performed by dissolving or dispersing silicone oil in a suitable solvent and then mixing with the base silica fine powder to remove the solvent.

  The addition amount of the inorganic particles is preferably 0.1% by mass or more and 30% by mass or less as a mass ratio in the surface layer after coating. If the amount is too small, the effect of stabilizing the charging by adding inorganic particles cannot be obtained. If the amount is too large, it takes time to control the viscosity of the surface layer coating material.

  The glass transition temperature Tg of the coating film serving as the surface layer is preferably 45 ° C. or higher, particularly preferably 50 ° C. or higher, at the peak temperature of the loss tangent tan δ measured by the viscoelasticity measurement method. When the temperature is lower than 45 ° C., there may be a problem that the photoconductor adheres to the photoconductor when left in contact with the photoconductor for a long period of time, or the surface of the charging roller is easily contaminated with toner. Although not particularly limited, too high Tg is not preferable because the flexibility of the resin is lost and the coating film is easily broken. Tg is adjusted by the ratio or amount of isocyanate to be crosslinked.

  The measuring method of the glass transition temperature Tg in the present invention is as follows. First, the surface layer coating sample for measurement is peeled off after the surface layer is peeled off from the roller state, or after being applied on a PET resin sheet or a fluorine resin sheet to form a surface layer coating film, about 5 mm × 40 mm Cut into strips. As a measuring device, a dynamic viscoelasticity measuring device RSA-II (trade name, manufactured by Rheometrics Scientific F.E.) is used, and a film tension fixture is used as a jig. The measurement was performed at a measurement frequency of 6.28 rad / sec and a temperature increase rate of 5 ° C./min. In an auto tension mode with an initial strain of 0.07 to 0.25%. The temperature dispersion of the loss tangent tan δ is measured, and the peak temperature is defined as Tg.

  A leveling agent may be mixed in the resin paint forming the surface layer. Examples of the leveling agent include silicone oil.

  The surface layer can be formed as follows. First, the material constituting the surface layer is dispersed by a known method using a conventionally known dispersion apparatus using beads such as a sand mill, a paint shaker, a dyno mill, and a pearl mill. Then, the obtained resin coating for forming the surface layer is coated on the surface of the charging member, in the present invention on the conductive elastic layer, by dipping, spray coating, roll coating, or ring coating. To do.

  The film thickness of the surface layer is preferably ½ to 10 times, more preferably 1 to 5 times the average particle size of the resin particles used as a roughening agent. If the film thickness of the surface layer is too large relative to the average particle diameter of the resin particles, the resin particles are buried in the film and it is difficult to form convex portions derived from the resin particles on the surface of the charging member. On the other hand, if it is too thin, resin particles may be lost due to contact with the photoreceptor or rubbing.

  The film thickness of the surface layer can be measured by cutting the roller cross section with a sharp blade at the position shown in FIGS. 3A and 3B and observing it with an optical microscope or an electron microscope.

  In order to adjust the film thickness of the surface layer, the solid content of the surface layer paint and the coating pull-up speed are controlled. When the solid content of the resin in the surface layer forming coating is increased, the film thickness of the surface layer is increased, and when the solid content is decreased, the film thickness is decreased. In the surface layer coating material of this invention, it is preferable to adjust solid content of resin with respect to the solvent to volatilize to 10-40 mass%. Further, when the coating pulling speed is increased, the film thickness is increased, and when the coating pulling speed is decreased, the film thickness is decreased. Therefore, in the present invention, the coating pulling speed is set to 20 to 5000 mm / min. It is preferable to adjust to.

  The surface roughness of the surface layer is preferably 3 μm or more and 20 μm or less in terms of a ten-point average roughness Rzjis according to JIS B0601-2001. More preferably, the ten-point average roughness Rzjis is 5 μm or more and 15 μm or less. If the surface roughness is too large, the surface of the conductive roller tends to become dirty with toner, external additives, and the like. Moreover, there is a possibility that the charging becomes non-uniform. On the other hand, if the surface roughness is too small, the effect of suppressing streaky charging failure (effect of discharge in the nip) is difficult to appear, which is not preferable. It has been found by our examination that when Rzjis is less than 3 μm, almost no discharge in the nip occurs.

  The ten-point average roughness (Rzjis) is measured based on the surface roughness of JIS B0601-2001, using a surf coder SE3400 (trade name) manufactured by Kosaka Laboratories in three axial directions and 2 in the circumferential direction. Measure each of a total of 6 points, and take the average value. In the present invention, the contact needle is a diamond having a tip radius of 2 μm, a measurement speed of 0.5 mm / s, a cutoff λc of 0.8 mm, a reference length of 0.8 mm, and an evaluation length of 8.0 mm.

  In order to obtain a charging member having a surface roughness in the above range, the surface roughness of the conductive elastic layer, the film thickness of the surface layer, the average particle diameter of the resin particles and the amount added are adjusted.

  However, in order to form a void derived from the convex portion on the surface of the charging member at the nip portion with the photoconductor, the surface roughness of the conductive elastic layer is reduced, and the average particle diameter and addition amount of the resin particles are used. There was a tendency to adjust the roughness.

  On the other hand, when the surface roughness was adjusted with the conductive elastic layer, the effect of suppressing streaky charging failure tended to be smaller than when the surface roughness was adjusted with the resin particles described above. This is considered to be because the conductive elastic layer is relatively soft and is compressed and deformed by the contact pressure with the photosensitive member, so that a sufficient gap cannot be formed.

  Based on the above examination results, the ten-point average roughness on the surface of the conductive elastic layer is Rzjis, preferably 10 μm or less, more preferably 5 μm or less.

The electrical resistance of the charging member of the present invention is 1 × 10 ⁴ Ω or more in a high temperature and high humidity environment of 30 ° C./80% RH, and 1 × in a low temperature and low humidity environment of 15 ° C./10%. It is preferably 10 ⁸ Ω or less. A method for measuring the electrical resistance will be described later.

It is preferable that the electrical resistance in the low-temperature and low-humidity environment is 1 × 10 ⁸ Ω or less as described above because the photosensitive drum can be charged to a predetermined potential and a ghost image hardly occurs. Also, if the electrical resistance in the high temperature and high humidity environment is 1 × 10 ⁴ Ω or more as described above, even if there is a pinhole in the photoconductor, almost no voltage drop of the applied voltage occurs. This is preferable because it does not appear as a strip-like image defect.

In order to set the electric resistance within the above range, for example, the volume resistivity of the conductive elastic layer of the charging member is adjusted to 1 × 10 ⁴ to 1 × 10 ⁸ Ω · cm, and the volume resistivity of the surface layer is What is necessary is just to adjust so that it may be 1 * 10 < ⁶ > -1 * 10 < ¹⁵ > (omega | ohm) * cm and the film thickness of a surface layer may be 1-100 micrometers.

<2> Image Forming Apparatus The image forming apparatus of the present invention is an electrophotographic image forming apparatus having at least a process cartridge in which the charging member and the member to be charged of the present invention are integrated at least, an exposure unit, and a developing unit. It is. The process cartridge will be described later.

  FIG. 4 shows an image forming apparatus using a charging roller 5 which is an embodiment of the charging member in the present invention. The photosensitive drum 4 serving as an image carrier is primarily charged by the charging roller 5 while rotating in the direction of the arrow, and then exposed to exposure 11 by an exposure unit to form an electrostatic latent image.

  Further, the toner supplied by the toner supply roller 14 and thinned on the developing roller 6 as the developing means by the elastic regulating blade 13 is then brought into contact with the surface of the photosensitive drum 4 so that an electrostatic latent image is formed. The developed toner image is developed.

  The developed toner image is transferred from the photosensitive drum 4 to the print medium 7 as the transfer target member in the developing portion between the transfer roller 8 as the transfer member and the photosensitive drum 4, and then heated and fixed in the fixing portion 9. It is fixed by pressure and becomes a permanent image. The latent image remaining on the photosensitive drum 4 is exposed by the pre-charging exposure device 12, and the potential of the photosensitive drum 4 returns to the ground potential. The untransferred toner that has not been transferred is collected by a cleaning blade 10 that is a cleaning means.

  Voltages are respectively applied to the developing roller 6, the charging roller 5, and the transfer roller 8 from power sources 18, 19, and 20 of the image forming apparatus.

  Here, only a DC voltage is applied from the power source 19 to the charging roller 5 which is the charging member of the present invention. By using a DC voltage as the applied voltage, there is an advantage that the cost of the power supply can be kept low. In addition, there is an advantage that no charging noise is generated when an AC voltage is applied. The absolute value of the DC voltage to be applied is preferably the sum of the discharge start voltage of air and the primary charging potential of the surface of the member to be charged (photosensitive member surface). Usually, the discharge start voltage of air is about 500 to 700 V, and the primary charging potential of the photoreceptor surface is about 300 to 800 V. Therefore, the specific primary charging voltage is preferably 800 to 1500 V.

  When a color image forming apparatus is used, four process cartridges (black, cyan, magenta, yellow) described later can be prepared and arranged in series.

<3> Process Cartridge The process cartridge of the present invention is formed by integrating at least the charging member of the present invention and the member to be charged, and the convex portion of the surface layer of the charging member has a gap at the nip portion with the member to be charged. It can be detachable from the main body of the electrophotographic image forming apparatus.

  In the process cartridge of the present invention, the developing means and the cleaning means may be integrated. For example, as shown in FIG. 5, the photosensitive drum 4, the charging roller 5, the developing roller 6, the toner supply roller 14, and the cleaning blade 10 are integrally supported and are detachable from the main body of the image forming apparatus.

  Before the electrophotographic process cartridge is used, it is preferable to avoid contact between the developing roller 6 and the toner with the toner seal 30.

  Hereinafter, the present invention will be described in more detail with reference to specific examples, but the scope of the present invention is not limited thereto.

<Production Example of Resin Particle [A1]>
-34.9 parts by mass of terephthalic acid-32.7 parts by mass of 1,4-butanediol-56.3 parts by mass of polyethylene glycol (number average molecular weight 2000)-0.1 parts by mass of tetrabutyl titanate-0.3 parts by antioxidant Part by mass (Product name: Irganox 1010, manufactured by Ciba Geigy Corp.)
Was charged in an esterification reaction can and reacted at 220 ° C. for 2 hours in a nitrogen gas atmosphere.

  Next, after the reaction solution was transferred to a polymerization can, 0.1 part of tetrabutyl titanate was added, and polymerization was performed at 250 ° C. under a condition of 0.5 mmHg or less for 3 hours. After the polymerization was completed, the obtained polymer was discharged onto a cooling belt in a gut shape and pelletized to prepare a pellet-like polyether ester.

100 parts by mass of the polyether ester obtained above and 200 parts by mass of polyethylene oxide (manufactured by Meisei Chemical Industry Co., Ltd., trade name: R150) were dry blended with a tumbler mixer, and at 260 ° C. with a twin screw extruder. The mixture was kneaded with heating to obtain a mixture. The obtained mixture was cooled to about 150 ° C. and then mixed with 2000 parts by mass of water as a dispersion medium to obtain a suspension of polyether ester particles. This was subjected to centrifugal separation to separate the desired polyether ester resin particles, followed by drying by heating to obtain substantially true spherical polyether ester resin particles [A1] having an average particle diameter of 10 μm. The obtained resin particles [A1] had a volume resistivity of 7.0 × 10 ⁸ Ω · cm.

  The polyethylene oxide used here is incompatible with the polyether ester and is water-soluble. The polyether ester is insoluble in water.

<Production Example of Resin Particle [A2]>
By reacting acrylonitrile with polyethylene glycol having a number average molecular weight of 4,000 and further carrying out a hydrogenation reaction, polyethylene glycol diamine having both amino groups at both ends was obtained. This and terephthalic acid were subjected to a salt reaction by a conventional method to obtain a 40% by mass aqueous solution of polyethylene glycol diammonium terephthalate.

  200 parts of the above 40% by weight polyethylene glycol diammonium terephthalate aqueous solution, 102 parts of caprolactam, and 16 parts of 40% by weight hexamethylene diammonium adipate aqueous solution were added to the concentration can, and then the temperature was increased to 110 ° C. and concentrated to 80% by weight. .

  Subsequently, after the concentrated liquid was transferred to the polymerization can, the temperature was raised to 120 ° C. with nitrogen substitution, and 1,3,5-trimethyl-2,4,6-tri (3,5-di-t-butyl-hydroxy After adding 10 parts of (benzyl) benzene, the mixture was heated and stirred to 245 ° C. Polymerization was carried out at 245 ° C. for 10 hours to obtain a viscous and transparent polymer. The obtained polymer was discharged onto a cooling belt in a gut shape and pelletized to prepare a pellet-like polyetheramide.

100 parts by mass of the polyetheramide obtained above and 200 parts by mass of polyethylene oxide (trade name: R150, manufactured by Meisei Chemical Industry Co., Ltd.) were dry-blended with a tumbler mixer, and 240 ° C. with a twin screw extruder. The mixture was kneaded with heating to obtain a mixture. The obtained mixture was cooled to about 150 ° C. and then mixed with 2000 parts by mass of water as a dispersion medium to obtain a suspension of polyetheramide particles. This was subjected to centrifugal separation to separate the desired polyetheramide resin particles, followed by heating and drying to obtain substantially true spherical polyetheramide resin particles [A2] having an average particle diameter of 10 μm. The obtained resin particles [A2] had a volume resistivity of 1.0 × 10 ⁸ Ω · cm.

  The polyethylene oxide used here is incompatible with polyether amide and is water-soluble. In addition, the polyetheramide is insoluble in water.

<Production Example of Resin Particle [A3]>
-Adipic acid 21.9 parts by mass-4-butanediol 24.3 parts by mass-Hexamethylenediamine-Adipic acid 81.2 parts by mass-Tetrabutyl titanate 0.05 parts by mass were put together in a reaction can and nitrogen gas atmosphere Under stirring, the mixture was heated for 3 hours at a temperature of 230 ° C., and a mixture of water, tetrahydrofuran and 1,4-butanediol was distilled out of the system.

  Next, the reaction mixture was transferred to a polymerization reaction vessel, and 0.05 parts by mass of tetrabutyl titanate and 0.2 parts by mass of an antioxidant (trade name: Irganox 1010, manufactured by Ciba Geigy Co., Ltd.) were added. Thereafter, the reaction conditions were about 270 ° C. and 0.1 mmHg or less in about 1 hour, and the polymerization reaction was further continued for 2 hours to obtain a transparent viscous polymer. The obtained polymer was discharged from the polymerization vessel into water in a gut shape and pelletized through a cutter. In this way, a pelletized polyesteramide was obtained.

100 parts by mass of the polyesteramide obtained above and 200 parts by mass of polyethylene oxide (trade name: R150, manufactured by Meisei Chemical Industry Co., Ltd.) are dry blended with a tumbler mixer and heated at 260 ° C. with a twin screw extruder. While kneading, a mixture was obtained. The obtained mixture was cooled to about 150 ° C. and then mixed with 2000 parts by mass of water as a dispersion medium to obtain a suspension of polyesteramide particles. This was subjected to centrifugal separation to separate the desired polyesteramide resin particles, followed by heating and drying to obtain almost true spherical polyesteramide resin particles [A3] having an average particle diameter of 10 μm. The obtained resin particles [A3] had a volume resistivity of 1.0 × 10 ⁹ Ω · cm.

  The polyethylene oxide used here is incompatible with the polyesteramide and is water-soluble. Polyesteramide is also water-insoluble.

<Production Example of Resin Particle [A4]>
Ε-Caprolactam 83.5 parts by mass Bisphenol A ethylene oxide adduct 192 parts by mass (number average molecular weight 2,000)
-16.5 parts by mass of terephthalic acid-0.5 parts by mass of antioxidant (trade name: Irganox 1010, manufactured by Ciba Gaiky)
・ Zirconyl acetate 0.5 parts by mass ・ 7 parts by mass of water were charged, heated and stirred at 220 ° C. for 4 hours under a nitrogen gas atmosphere to obtain a homogeneous solution, and then subjected to 245 ° C. under reduced pressure of 1 mmHg or less. For 5 hours to obtain a viscous polymer. This polymer gut was discharged into water and pelletized through a cutter to obtain polyetheresteramide pellets.

100 parts by mass of the polyether ester amide obtained above and 200 parts by mass of polyethylene oxide (manufactured by Meisei Chemical Industry Co., Ltd., trade name: R150) were dry blended with a tumbler mixer, and 250 ° C. with a twin screw extruder. The mixture was obtained by kneading while heating. The obtained mixture was cooled to about 150 ° C. and then mixed with 2000 parts by mass of water as a dispersion medium to obtain a suspension of polyetheresteramide particles. This was subjected to centrifugal separation to separate the desired polyether ester amide resin particles, followed by drying by heating to obtain substantially true spherical polyether ester amide resin particles [A4] having an average particle size of 10 μm. . The obtained resin particles [A4] had a volume resistivity of 5.0 × 10 ⁷ Ω · cm.

  The polyethylene oxide used here is incompatible with the polyether ester amide and is water-soluble. Further, the polyether ester amide is insoluble in water.

<Production Example of Resin Particle [A5]>
Polyether ester amide resin particles [A5] having a substantially spherical shape with an average particle diameter of 1.2 μm were obtained in the same manner as in the production example of resin particles [A4]. The obtained resin particles [A5] had a volume resistivity of 5.0 × 10 ⁷ Ω · cm.

<Production Example of Resin Particle [A6]>
Polyether ester amide resin particles [A6] having a substantially spherical shape with an average particle diameter of 28 μm were obtained in the same manner as in the production example of resin particles [A4]. The obtained resin particles [A6] had a volume resistivity of 5.0 × 10 ⁷ Ω · cm.

<Production Example of Resin Particle [A7]>
Polyether ester amide resin particles [A7] having a substantially spherical shape with an average particle diameter of 3 μm were obtained in the same manner as in the production example of resin particles [A4]. The obtained resin particles [A7] had a volume resistivity of 5.0 × 10 ⁷ Ω · cm.

<Production Example of Resin Particle [A8]>
Resin particles [A8] of polyether ester amide having a substantially spherical shape with an average particle diameter of 20 μm were obtained in the same manner as in the production example of resin particles [A4]. The volume resistivity of the obtained resin particles [A8] was 5.0 × 10 ⁷ Ω · cm.

<Production Example of Resin Particle [A9]>
A polyether ester having a substantially spherical shape with an average particle diameter of 10 μm is the same as the production example of the resin particle [A4], except that the polyether ester amide is Perestat NC6321 (trade name) manufactured by Sanyo Chemical Industries, Ltd. Amide resin particles [A9] were obtained. The obtained resin particles [A9] had a volume resistivity of 8.0 × 10 ⁵ Ω · cm.

<Production Example of Resin Particle [A10]>
Resin particles of polyether ester having a substantially spherical shape with an average particle diameter of 10 μm, in the same manner as in the production example of resin particles [A1] except that the polyether ester is Perprene P30B (trade name) manufactured by Toyobo Co., Ltd. [A10] was obtained. The obtained resin particles [A10] had a volume resistivity of 5.0 × 10 ¹⁰ Ω · cm.

<Production Example of Resin Particle [A11]>
100 parts by mass of polyester resin and 200 parts by mass of polyethylene oxide (Madesei Chemical Co., Ltd., trade name: R150) are dry-blended with a tumbler mixer and kneaded while heating at 250 ° C. with a twin screw extruder, A mixture was obtained. In addition, as the polyester resin, pellets of polybutylene terephthalate (PBT, manufactured by Polyplastics, trade name: DURANEX 800FP) were used. The obtained mixture was cooled to about 150 ° C. and then mixed with 2000 parts by mass of water as a dispersion medium to obtain a suspension of polyester resin particles. This was separated from the desired polyester resin particles by centrifugal separation, and then dried by heating to obtain substantially spherical resin resin particles having an average particle diameter of 10 μm. This is designated as resin particle [A11]. The obtained resin particles [A11] had a volume resistivity of 1.0 × 10 ¹⁶ Ω · cm.

<Production Example of Resin Particle [A12]>
Polyether ester amide resin particles [A12] having a substantially true spherical shape with an average particle diameter of 0.4 μm were obtained in the same manner as in the production example of resin particles [A4]. The obtained resin particles [A12] had a volume resistivity of 5.0 × 10 ⁷ Ω · cm.

<Production Example of Resin Particle [A13]>
Resin particles [A13] of polyether ester amide having a substantially spherical shape with an average particle diameter of 36 μm were obtained in the same manner as in the production example of resin particles [A4]. The obtained resin particles [A13] had a volume resistivity of 5.0 × 10 ⁷ Ω · cm.

<Production Example of Resin Particle [B1]>
・ Epichlorohydrin rubber 100 parts by mass (Epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer)
-10 parts by weight of calcium carbonate-1 part by weight of zinc stearate-5 parts by weight of zinc oxide-1 part by weight of 2-mercaptobenzimidazole was kneaded for 10 minutes with a closed mixer. Furthermore, 1 part by mass of DM (2-benzothiazolyl disulfide) as a vulcanization accelerator, 0.5 part by mass of TS (tetramethylthiuram monosulfide) as a vulcanization accelerator, 1 part by mass of sulfur was added and further kneaded with an open roll for 5 minutes.

The kneaded product was frozen and pulverized at a liquid nitrogen temperature, and then classified so that the average particle size was 12 μm. Then, epichlorohydrin rubber (epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer) particles having an average particle diameter of 12 μm were obtained. This is designated as resin particle [B1]. The obtained resin particles [B1] had a volume resistivity of 9.0 × 10 ⁶ Ω · cm.

<Production Example of Resin Particle [B2]>
The blend composition shown below was used instead of 100 parts by mass of epichlorohydrin rubber (epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer) used in the production example of the resin particle [B1].
-75 parts by mass of ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer-25 parts by mass of epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer Other than that, the same manner as in the production example of resin particles [B1] To obtain a kneaded product. The obtained kneaded product was freeze-ground in the same manner as in the production example of the resin particles [B1], and then classified so that the average particle size was 10.5 μm. Then, blend composition particles of an ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer having an average particle size of 10.5 μm and an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer were obtained. This is designated as resin particle [B2]. The obtained resin particles [B2] had a volume resistivity of 6.5 × 10 ⁶ Ω · cm.

<Production Example of Resin Particle [B3]>
-70 parts by weight of acrylonitrile butadiene rubber (NBR)-30 parts by weight of propylene oxide-ethylene oxide copolymer-10 parts by weight of calcium carbonate-1 part by weight of zinc stearate-5 parts by weight of zinc oxide-1 part by weight of 2-mercaptobenzimidazole Was kneaded for 10 minutes with a closed mixer. Furthermore, 4.5 parts by mass of TBzTD (tetrabenzylthiuram disulfide) as a vulcanization accelerator and 1.2 parts by mass of sulfur as a vulcanizing agent were added to the kneaded product, and further kneaded with an open roll for 5 minutes.

The kneaded product was frozen and pulverized at a liquid nitrogen temperature, and then classified so that the average particle size was 5 μm. And the blend composition particle | grains of the acrylonitrile butadiene rubber (NBR) with a mean particle diameter of 5 micrometers and a propylene oxide-ethylene oxide copolymer were obtained. This is designated as resin particle [B3]. The obtained resin particles [B3] had a volume resistivity of 8.0 × 10 ⁹ Ω · cm.

<Production Example of Resin Particle [B4]>
Resin particles having an average particle diameter of 1.8 μm were obtained in the same manner as in the production example of the resin particles [B1] except that the particles were classified so that the average particle diameter was 2 μm. This is designated as resin particle [B4]. The obtained resin particles [B4] had a volume resistivity of 1.2 × 10 ⁷ Ω · cm.

<Production Example of Resin Particle [B5]>
Resin particles having an average particle diameter of 19.8 μm were obtained in the same manner as in the production example of resin particles [B1] except that the particles were classified so that the average particle diameter was 20 μm. This is designated as resin particle [B5]. The obtained resin particles [B5] had a volume resistivity of 9.8 × 10 ⁶ Ω · cm.

<Production Example of Resin Particle [B6]>
Resin particles having an average particle diameter of 29.5 μm were obtained in the same manner as in the production example of resin particles [B1] except that the particles were classified so that the average particle diameter was 30 μm. This is designated as resin particle [B6]. The obtained resin particles [B6] had a volume resistivity of 2.2 × 10 ⁷ Ω · cm.

<Production Example of Resin Particle [B7]>
Resin particles having an average particle diameter of 36 μm were obtained in the same manner as in the production example of resin particles [B1] except that the particles were classified so that the average particle diameter was 35 μm. This is designated as resin particle [B7]. The volume resistivity of the obtained resin particles [B7] was 1.6 × 10 ⁷ Ω · cm.

<Production Example of Resin Particle [B8]>
Resin particles having an average particle diameter of 0.5 μm were obtained in the same manner as in the production example of the resin particles [B1] except that classification was performed so that the average particle diameter was 0.5 μm. This is designated as resin particle [B8]. The obtained resin particles [B8] had a volume resistivity of 9.9 × 10 ⁶ Ω · cm.
<Production Example of Resin Particle [B9]>
The polyester resin (polybutylene terephthalate) pellets were pulverized in the same manner as in the production example of the resin particles [B1], and classified so that the average particle size was 10 μm. Polyester resin particles having an average particle size of 9.9 μm were obtained. Obtained. This is designated as resin particle [B9]. The obtained resin particles [B9] had a volume resistivity of 1.0 × 10 ¹⁶ Ω · cm.

(Example A1)
[Preparation of conductive substrate]
A stainless steel core having a diameter of 6 mm and a length of 252.5 mm was used as a support. A thermosetting adhesive (trade name: METALOC U-20, manufactured by Toyo Chemical Laboratories) was applied to this and dried.

next,
Epichlorohydrin rubber terpolymer 100 parts by mass (ethylene oxide (EO) / epichlorohydrin (EP) / allyl glycidyl ether (AGE) = (73 mol% / 23 mol% / 4 mol%))
-Calcium carbonate 60 parts by mass-Aliphatic polyester plasticizer 8 parts by mass-Zinc stearate 1 part by mass-Anti-aging agent 0.5 part by mass (2-mercaptobenzimidazole (MB))
・ Zinc oxide 2 parts by mass ・ Quaternary ammonium salt 2 parts by mass ・ Carbon black 5 parts by mass (average particle size: 100 nm, volume resistivity: 0.1 Ω · cm)
Was kneaded for 10 minutes in a closed mixer adjusted to 50 ° C. to prepare a raw material compound. Into this raw material compound, 1% by mass of sulfur (vulcanizing agent), 1% by mass of dibenzothiazyl sulfide (DM) (vulcanization accelerator) and 0.5% by mass with respect to the epichlorohydrin rubber terpolymer. Of tetramethylthiuram monosulfide (TS) was added. And it knead | mixed for 10 minutes with the double roll machine cooled to 20 degreeC, and obtained the compound for elastic layers.

  This elastic layer compound is extruded on an adhesive-coated support by an extrusion molding machine to form a roller shape having an outer diameter of about 9 mm, and then in an electric oven at 160 ° C. for 1 hour. Vulcanization and curing of the adhesive were performed. After cutting off both ends of the rubber to make the rubber length 228 mm, the surface was polished so as to form a roller shape having an outer diameter of 8.5 mm, and an elastic layer was formed on the support. At this time, the crown amount (difference in outer diameter at a position 90 mm away from the central portion and the central portion) was 120 μm.

[Preparation of conductive composite fine particles]
To 7.0 kg of silica particles (average particle diameter 15 nm, volume resistivity 1.8 × 10 ¹² Ω · cm) as metal oxide particles, 140 g of methyl hydrogen polysiloxane was added while the edge runner was running. The mixture was stirred for 30 minutes with a linear load of 588 N / cm (60 Kg / cm). The stirring speed at this time was 22 rpm.

Next, 7.0 kg of carbon black particles (average particle size 28 nm, volume resistivity 1.0 × 10 ² Ω · cm, pH = 6.5) was added over 10 minutes while the edge runner was operated. Furthermore, after mixing and stirring for 60 minutes at a linear load of 588 N / cm (60 kg / cm), carbon black was adhered to the methylhydrogenpolysiloxane coating, and then dried at 80 ° C. for 60 minutes using a dryer. Composite fine particles were obtained. The stirring speed at this time was 22 rpm. The obtained conductive composite fine particles had an average particle size of 15 nm and a volume resistivity of 2.3 × 10 ² Ω · cm.

[Production of titanium oxide particles]
1000 g of acicular rutile type titanium oxide particles (average particle size 15 nm, length: width = 3: 1), volume resistivity 5.2 × 10 ¹⁰ Ω · cm), 110 g of isobutyltrimethoxysilane as a surface treatment agent, toluene as a solvent A slurry was prepared by blending 3000 g. This slurry was mixed with a stirrer for 30 minutes, and then supplied to Viscomill in which 80% of the effective internal volume was filled with glass beads having an average particle diameter of 0.8 mm, and wet crushing was performed at a temperature of 35 ± 5 ° C. .

  The slurry obtained by the wet pulverization treatment was subjected to distillation under reduced pressure (bath temperature: 110 ° C., product temperature: 30 to 60 ° C., degree of vacuum: about 100 Torr) using a kneader, and surfaced at 120 ° C. for 2 hours. The treating agent was baked. The particles after baking were cooled to room temperature and then pulverized using a pin mill.

[Preparation of paint for surface layer formation]
Methyl isobutyl ketone was added to a caprolactone-modified acrylic polyol solution (trade name: Plaxel DC2016, manufactured by Daicel Chemical Industries, Ltd.) to adjust the solid content to 17% by mass. For 411.8 parts by mass of this solution (100 parts by mass of the solid content of the acrylic polyol solution),
-50 parts by mass of the above-mentioned composite conductive fine particles-30 parts by mass of the above titanium oxide particles-0.24 parts by mass of modified dimethyl silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.)
-Hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) 7: 3 mixture of each butanone oxime block body 56 mass parts was put, and the mixed solution was adjusted. At this time, the mixture of the block HDI and the block IPDI was added so that “NCO / OH = 1.0”. For HDI and IPDI, HDI (trade name: Duranate TPA-B80E, manufactured by Asahi Kasei Chemicals Corporation) and IPDI (trade name: Bestanat B1370, manufactured by Degussa) were used.

  In a 450 mL glass bottle, 200 parts by mass of a total of 548.04 parts by mass of the above mixed solution and 200 parts by mass of glass beads having an average particle size of 0.8 mm as media were mixed and dispersed for 72 hours using a paint shaker disperser. . After dispersion, 2.72 parts by mass of resin particles [A1] (corresponding to 10 parts by mass with respect to 100 parts by mass of the solid content of the acrylic polyol solution) was added, and then dispersed for another 30 minutes, and then the glass beads were filtered. Thus, a coating material for forming a surface layer was obtained.

  This surface layer-forming coating material was dipped on the conductive substrate once, air-dried at room temperature for 30 minutes or more, then dried in a hot air circulating dryer set at 80 ° C. for 1 hour, and further set at 160 ° C. It dried for 1 hour with the hot air circulation dryer, and formed the surface layer on the electroconductive base | substrate. The dipping coating dipping time is 9 seconds, the dipping coating lifting speed is adjusted so that the initial speed is 20 mm / s, and the final speed is 2 mm / s. Between 20 mm / s and 2 mm / s is linear with respect to time. The speed was changed.

  In this way, a charging member having a surface layer on a conductive substrate was produced. The ten-point average roughness (Rzjis) measurement on the surface of the obtained charging member was performed using the method described above. The results are shown in Table 1. In addition, the addition part number of the resin particle of Table 1 is the addition part number when the solid content of the acrylic polyol is 100 parts by mass.

[Image evaluation]
<Stain adhesion promotion test>
The manufactured charging member was mounted on a process cartridge and incorporated in an electrophotographic apparatus having the configuration shown in FIG. 10 (the electrophotographic photosensitive drum having a diameter of 24 mm was pushed by a spring having a weight of 0.5 kg at one end and a total weight of 1 kg at both ends. Abut with pressure). Then, under a 23 ° C./50% RH environment (NN environment), after printing 50 single-color solid images, one solid white image was printed. This process was repeated 6 times, and a total of 300 single-color solid images were printed to obtain a charging member in which the surface was forcibly contaminated with toner or an external additive in advance. The charging member was applied with a direct current voltage of −1000 V only. As the electrophotographic photosensitive drum, a photosensitive drum mounted on a monochrome (black) cartridge of HP Color LaserJet 3000 (trade name, manufactured by Hewlett Packard) was used.

  The charging member subjected to the dirt adhesion promotion test as described above was mounted on another process cartridge, and a durability test was performed.

[Evaluation of endurance image (dirt image, defective discharge image, charged horizontal stripe image and spot image)]
The manufactured charging member was mounted on a process cartridge and incorporated in an electrophotographic apparatus having the configuration shown in FIG. 10 (the electrophotographic photosensitive drum having a diameter of 24 mm was pushed by a spring having a weight of 0.5 kg at one end and a total weight of 1 kg at both ends. Abut with pressure). Only -DC voltage was applied to the charging member at -1000V. As the electrophotographic photosensitive drum, a photosensitive drum mounted on a monochrome (black) cartridge of HP Color LaserJet 3000 (trade name, manufactured by Hewlett Packard) was used. When one image was output, the rotation of the electrophotographic apparatus was stopped, and the operation of restarting the image forming operation was repeated (intermittent durability at a printing rate of 1%), and an image output durability test for 5000 sheets was performed.

  During the durability test, halftone images were output at the 1000th, 3000th, and 5000th time points, and the occurrence of streak-like images due to dirt was evaluated from the images. Further, with respect to the halftone image at the time of the 5000th sheet, the state of occurrence of a charged horizontal streak image and a spot image due to resistance unevenness was evaluated. The evaluation of the occurrence state was performed according to the following evaluation criteria.

<Evaluation criteria for streaky image, charged horizontal streak image, and point-like image>
◎: Not generated ○: Only slight occurrence Δ: Occurrence is observed in a part of the image, but there is no problem in practical use ×: Image quality deteriorates due to occurrence Here, the process speed was set to 80 mm / s during the durability test The environment was set in three environments of 23 ° C./50% RH (NN environment), 15 ° C./10% RH (LL environment), and 30 ° C. × 80% RH (HH environment). In addition, in 15 degreeC / 10% RH (LL environment), durability evaluation was performed on two conditions, process speed 80mm / s and 240mm / s.

  The evaluation results are shown in Table 1. The streak-like image, the charged horizontal streak image, and the point-like image were not generated during the durability evaluation, and a good image could be maintained.

(Example A2)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A2]. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 7 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 1. A good image could be maintained as in Example A1.

(Example A3)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A3]. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 7 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 1. A good image could be maintained as in Example A1.

(Example A4)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A4]. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 7 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 1. A good image could be maintained as in Example A1.

(Example A5)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A5] and the number of added parts was changed to 60 parts by mass. The 10-point average roughness (Rzjis) on the surface of the obtained charging member was 10 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 1. In the evaluation of 240 mm / s in which the process speed is high in the LL environment, only a slight charged horizontal streak image was generated, and a good image was maintained under other conditions.

(Example A6)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A6]. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 18 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 1. In the evaluation of the NN and LL environments, only a slight spot-like image was generated, and a good image was maintained under other conditions.

(Example A7)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A7]. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 3.3 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 1. In the evaluation of 240 mm / s in which the process speed is high in the LL environment, only a slight charged horizontal streak image was generated, and a good image was maintained under other conditions.

(Example A8)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A8] and the number of added parts was changed to 20 parts by mass. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 19.7 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 1. In the evaluation of 240 mm / s, which is a fast process speed in the LL environment, only a slight spot-like image was generated, and a good image was maintained under other conditions.

(Example A9)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A9]. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 7 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 1. A spot-like image was generated in an HH environment, but it was at a level with no problem in practical use. Good images were maintained under other conditions.

(Example A10)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A10]. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 7 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. In the evaluation of 240 mm / s, which is a fast process speed in the LL environment, generation of a smudge image is recognized in the second half of the endurance, but the level is practically satisfactory. Good images were maintained under other conditions.

(Comparative Example A1)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A11]. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 7 μm. The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 2. In the evaluation, defective images due to dirt were conspicuous.

(Comparative Example A2)
A charging member was produced in the same manner as in Example A1, except that no resin particles were added. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 2.1 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 2. In the evaluation, a charged horizontal streak image was conspicuous.

(Comparative Example A3)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A12] and the number of added parts was changed to 20 parts by mass. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 1.8 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 2. In the evaluation, a charged horizontal streak image was conspicuous.

(Comparative Example A4)
A charging member was produced in the same manner as in Example A1, except that the resin particle [A1] was changed to the resin particle [A13]. The ten-point average roughness (Rzjis) on the surface of the obtained charging member was 26 μm.

  The charging member was subjected to a stain adhesion promoting test in the same manner as in Example A1, and then subjected to a durability image evaluation. The results are shown in Table 2. In the evaluation, defective images and spot images due to dirt were conspicuous.

Explanation of abbreviations in Tables 1 and 2:
(Types of resin particles)
PEEs: Polyetherester PEA: Polyetheramide PEsA: Polyesteramide PEEsA: Polyetheresteramide PBT: Polybutylene terephthalate (Example B1)
<Production of charging roller>
(1) Preparation of conductive elastic layer / Epichlorohydrin rubber 100 parts by mass (Epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer)
・ 50 parts by weight of filler (calcium carbonate, trade name: Nanox # 30, manufactured by Maruo Calcium)
・ Lubricant 1 part by mass (zinc stearate)
・ Reinforcing material for improving abrasiveness 5 parts by mass (carbon black, FEF)
-5 parts by mass of zinc oxide-5 parts by mass of plasticizer (copolymer of sebacic acid and propylene glycol, number average molecular weight 8000)
-2 parts by mass of perchloric acid quaternary ammonium salt (the following compounds)

-Anti-aging agent 1 part by mass (2-mercaptobenzimidazole)
Was kneaded for 10 minutes with a closed mixer. Furthermore, 1 part by mass of DM (2-benzothiazolyl disulfide) as a vulcanization accelerator, 0.5 part by mass of TS (tetramethylthiuram monosulfide) as a vulcanization accelerator, 1 mass of sulfur as a vulcanization agent Then, the mixture was further kneaded with an open roll for 5 minutes.

  The above-mentioned epichlorohydrin rubber kneaded material was extruded into a cylindrical shape having an outer diameter of 13.5 mm and an inner diameter of 5.5 mm using an extruder, cut into a length of 250 mm, and a steam vulcanizer was used, and the temperature was 160 ° C. Primary vulcanization was performed in water vapor for 40 minutes to obtain a conductive elastic layer rubber primary vulcanization tube.

  Next, a thermosetting adhesive of metal and rubber is applied to the central portion 231 mm in the axial direction of the cylindrical surface of a cylindrical conductive support (made of steel, surface is nickel-plated) having a diameter of 6 mm and a length of 256 mm, Dry at 80 ° C. for 10 minutes. The conductive support was inserted into the conductive elastic layer rubber primary vulcanization tube, and then heat-treated at 150 ° C. for 1 hour in an electric oven to obtain an unpolished layer roller.

  Cut off both ends of the rubber part of the unpolished layer roller to make the length of the rubber part 232 mm, and then polish the rubber part with a rotating grindstone. From the central part, 90 mm on both sides are 12.00 mm in diameter and the central part is The crown shape was 12.15 mm in diameter. A conductive elastic base layer roller having a conductive elastic layer with a surface ten-point average roughness Rzjis of 4.0 μm and a deflection of 25 μm was obtained.

(2) Preparation of surface layer Methyl isobutyl ketone was added to the caprolactone-modified acrylic polyol solution to adjust the solid content to 17% by mass. For 411.8 parts by mass of this solution (100 parts by mass of the solid content of the acrylic polyol solution),
Carbon black (HAF) 15 parts by mass Acicular rutile type titanium oxide fine particles 30 parts by mass (surface treated with hexamethylene disilazane and dimethyl silicone, average particle diameter 0.015 μm, length: width = 3: 1)
-Modified dimethyl silicone oil 0.08 parts by mass-56 parts by mass of a 7: 3 mixture of each butanone oxime block of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) was added to prepare a mixed solution. At this time, the mixture of the block HDI and the block IPDI was added so that “NCO / OH = 1.0”.

  In a 450 mL glass bottle, 200 parts by mass of a total of 512.88 parts by mass of the above mixed solution and 200 parts by mass of glass beads having an average particle diameter of 0.8 mm as media were mixed and dispersed for 24 hours using a paint shaker disperser. . After dispersion, 6.8 parts by mass of resin particles [B1] (corresponding to 25 parts by mass with respect to 100 parts by mass of acrylic polyol) are added, and further dispersed for 30 minutes, and then the glass beads are separated by filtration. A paint for forming the surface layer was obtained.

  This surface layer forming coating was dipped once on a conductive substrate (the conductive elastic base layer roller) and air-dried at room temperature for 30 minutes or more. Subsequently, it dried for 1 hour with the hot air circulating dryer set to 90 degreeC, and also dried for 1 hour with the hot air circulating dryer set to 160 degreeC, and formed the surface layer on the electroconductive base | substrate. The dipping coating dipping time is 9 seconds, the dipping coating lifting speed is adjusted so that the initial speed is 20 mm / s, and the final speed is 2 mm / s. Between 20 mm / s and 2 mm / s is linear with respect to time. The speed was changed.

  Thus, a charging roller having a surface layer on a conductive substrate was produced. The surface layer thickness of the obtained charging roller was 17 μm. Further, the ten-point average roughness (Rzjis) measurement on the surface of the obtained charging roller was performed using the method described above. The results are shown in Table 3.

<Evaluation of charging roller>
(1) Preparation for Evaluation: Dirt Adhesion Acceleration Test The charging roller manufactured as described above was mounted on a process cartridge for a color laser jet 3800 (trade name) manufactured by Canon, which was replaced with the charging roller. Using a color laser jet 3800 (trade name) equipped with this process cartridge, 50 single-color solid images were output continuously in a normal temperature and humidity environment (25 ° C., 50% RH), and then one solid white image. I passed the paper. This operation was repeated 6 times to output a total of 300 single-color solid images. By this operation, toner and external additives were forcibly adhered to the surface of the charging roller.

(2) Continuous multiple-sheet image output durability test Using the charging roller obtained as described above, evaluation was performed as follows. The electrophotographic laser printer used in this evaluation is an A4 vertical output machine, the output speed of the recording medium is 200 mm / sec and 100 mm / sec, and the resolution of the image is 600 dpi.

  For the primary charging, the charging roller forcibly adhered with dirt was used, and a DC voltage of −1100 V was applied to the charging roller. Evaluation is performed in a low-temperature and low-humidity environment (environment 1: 15 ° C./10% RH), a normal temperature and normal humidity environment (environment 2: 23 ° C./50% RH), and a high-temperature high humidity environment (environment 3: 30 ° C./80% RH). It was. Specifically, an endurance test for printing a plurality of images with a printing density of 4% (an image in which a horizontal line with a width of 2 dots and an interval of 50 dots is drawn in the direction perpendicular to the rotation direction of the photosensitive member) at a process speed of 200 mm / sec. went. Also, in each environment, halftone (image that draws a horizontal line with a width of 1 dot and an interval of 2 dots in the direction perpendicular to the rotation direction of the photoconductor) for image checking at the initial stage, after 3000 images and after 6000 images have been printed. ) Output image. In the image check, images were output at two process speeds and evaluated.

  The obtained image was visually observed, and fine streak-like density unevenness (lateral streak) generated due to uneven charging was evaluated. Rank A where the horizontal streak did not occur at all, Rank B where the level is slightly generated, Rank C where the level is slightly inconspicuous, but level C is slightly conspicuous Was ranked D. Rank E is a level where horizontal stripes are very conspicuous. The results are shown in Table 4.

  It should be noted that the image check after the 3,000 and 6,000 images were taken was performed immediately after the 3,000 and 6,000 images were taken and 12 hours later (hereinafter, the image check immediately after the last image is performed). Check, 12 hours later is called one image check in the morning).

(3) Measurement of charging roller resistance As a method of measuring electric resistance, first, as shown in FIG. 6A, the shaft 1 at both ends of the charging roller has the same curvature as that of the photosensitive member by bearings 33a and 33b to which a load is applied. The charging roller is brought into contact with the cylindrical metal 32 so as to be parallel. Next, as shown in FIG. 6B, 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 roller is driven and rotated while being in contact with the cylindrical metal. . At this time, the current flowing through the charging roller was measured with an ammeter 35 to calculate the resistance of the charging roller (in the present invention, a force of 5 N was applied to both ends of the shaft to contact a metal cylinder having a diameter of 30 mm, The metal cylinder was rotated at a peripheral speed of 45 mm / sec).

The electrical resistance was measured after leaving the charging roller of Example A1 in an N / N (normal temperature and normal humidity: 23 ° C./55% RH) environment for 24 hours or more, and it was 2.3 × 10 ⁵ Ω. .

(Example B2)
A charging roller was produced in the same manner as in Example B1, except that the resin particle [B1] was replaced with the resin particle [B2], and the number of added parts was changed to 40 parts by mass. The dipping pulling speed, the viscosity of the paint, the number of dippings, etc. were adjusted so that the film thickness of the surface layer was 20 μm. The surface layer thickness of the obtained charging roller was 19 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. Further, the electrical resistance was measured after leaving the charging roller of Example B2 in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more, and it was 3.7 × 10 ⁵ Ω. .

(Example B3)
A charging roller was produced in the same manner as in Example B1, except that the resin particle [B1] was changed to the resin particle [B3]. The dipping pulling speed, the viscosity of the paint, the number of dippings, etc. were adjusted so that the surface layer thickness was 15 μm. The surface layer thickness of the obtained charging roller was 14 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. Further, the electrical resistance was measured after leaving the charging roller of Example B3 in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more, and it was 1.3 × 10 ⁶ Ω. .

(Example B4)
A charging roller was produced in the same manner as in Example B1, except that the resin particle [B1] was replaced with the resin particle [B4] and the addition amount was equivalent to 50 parts by mass. The dipping pull-up speed, the paint viscosity, the number of dippings, etc. were adjusted so that the film thickness of the surface layer was 8 μm. The surface layer thickness of the obtained charging roller was 7.5 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. The electrical resistance was measured after leaving the charging roller of Example B4 in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more, and it was 8.4 × 10 ⁵ Ω. .

(Example B5)
A charging roller was produced in the same manner as in Example B1, except that the resin particle [B1] was changed to the resin particle [B5]. The dipping pull-up speed, the paint viscosity, the number of dippings, etc. were adjusted so that the film thickness of the surface layer was 35 μm. The surface layer thickness of the obtained charging roller was 36 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. The electrical resistance was measured after leaving the charging roller of Example B5 in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more, and it was 4.8 × 10 ⁵ Ω. .

(Example B6)
A charging roller was produced in the same manner as in Example B1, except that the resin particle [B1] was changed to the resin particle [B6]. The dipping pull-up speed, the paint viscosity, the number of dippings, etc. were adjusted so that the film thickness of the surface layer was 60 μm. The surface layer thickness of the obtained charging roller was 59 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. The electrical resistance was measured after leaving the charging roller of Example B6 in an N / N (normal temperature and normal humidity: 23 ° C./55% RH) environment for 24 hours or more, and it was 1.7 × 10 ⁶ Ω. .

(Comparative Example B1)
A charging roller was produced in the same manner as in Example B1, except that the resin particle [B1] was changed to the resin particle [B7]. The dipping pull-up speed, the paint viscosity, the number of dippings, etc. were adjusted so that the film thickness of the surface layer was 60 μm. The surface layer thickness of the obtained charging roller was 61.5 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. Further, the electrical resistance was measured after leaving the charging roller of Comparative Example B1 in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more, and it was 5.6 × 10 ⁶ Ω. .

(Comparative Example B2)
A charging roller was produced in the same manner as in Example B1, except that the resin particle [B1] was changed to the resin particle [B8]. The dipping pull-up speed, the paint viscosity, the number of dippings, etc. were adjusted so that the film thickness of the surface layer was 30 μm. The surface layer thickness of the obtained charging roller was 29 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. The electrical resistance was measured after leaving the charging roller of Comparative Example B2 in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more, and it was 4.9 × 10 ⁶ Ω. .

(Comparative Example B3)
A charging roller of Comparative Example B3 was obtained in the same manner as the charging roller of Example B1 except that no resin particles were added. The dipping pulling speed, the viscosity of the paint, the number of dippings, etc. were adjusted so that the film thickness of the surface layer was 17 μm as in Example B1. The surface layer thickness of the obtained charging roller was 15.5 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. Horizontal streaks were poorly charged from the beginning, and the level of horizontal streak-like image unevenness deteriorated as the number of durable sheets increased. Further, the electrical resistance was measured after leaving the charging roller of Comparative Example B3 in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more, and it was 7.9 × 10 ⁵ Ω. .

(Reference Example B1)
A charging roller was produced in the same manner as in Example B1, except that the resin particle [B1] was changed to the resin particle [B9]. The dipping pulling speed, the viscosity of the paint, the number of times of dipping, etc. were adjusted so that the film thickness of the surface layer was 17 μm. The surface layer thickness of the obtained charging roller was 16 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. In addition, when the charging roller of Reference Example B1 was left in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more and then the electrical resistance was measured, the charging roller was 3.0 × 10 ^6. Ω.

(Example B7)
Except that the ten-point average roughness (Rzjis) on the surface of the conductive elastic base layer roller was adjusted to 7.0 μm and the addition amount of the resin particles [B4] was changed to 20 parts by mass, the same as Example B4 Thus, a charging roller was produced. The dipping pull-up speed, the viscosity of the paint, the number of dippings, etc. were adjusted so that the film thickness of the surface layer was 10 μm. The surface layer thickness of the obtained charging roller was 9.5 μm. Further, the measurement results of the ten-point average roughness (Rzjis) on the surface of the obtained charging roller are shown in Table 3 as in Example B1.

This charging roller was subjected to a dirt adhesion promotion test in the same manner as in Example B1, and then subjected to a durable image evaluation. The results are shown in Table 4. Further, when the charging roller of Example B7 was left in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more and then the electrical resistance was measured, the charging roller was found to be 3.5 × 10 ^5. Ω.

In one embodiment of the charging member of the present invention, (a) a schematic view showing a cross section seen from the axial direction, (b) a schematic view showing a cross section seen from the direction perpendicular to the axial direction. The schematic of the non-contact laser length measuring device used for the measurement of the roller diameter of this invention and an outer diameter differential shake is shown. (A) Schematic diagram representing the cross section viewed from the axial direction, (b) Schematic diagram representing the cross section viewed from the direction perpendicular to the axial direction, the measurement location of the surface roughness and surface layer thickness of the roller of the present invention, It is. Moreover, (c) shows a schematic diagram of a cut section of the roller of the present invention. 1 is a schematic diagram showing a cross section of an embodiment of an image forming apparatus of the present invention. 1 is a schematic diagram showing a cross section of one embodiment of a process cartridge of the present invention. FIG. The (a) schematic before measurement and (b) the schematic at the time of a measurement of the apparatus used for the measurement of the electrical resistance value of the roller of the present invention are shown. The conceptual diagram showing the mode of the discharge of the nip part vicinity of the conventional surface smooth charging roller which does not have the convex part by a resin particle and a photosensitive drum is shown. The conceptual diagram showing the mode of the discharge in the nip part of the charging roller which has a convex part derived from an insulating resin particle, and a photosensitive drum is shown. FIG. 3 is a conceptual diagram showing a state of discharge in a nip portion between a charging roller and a photosensitive drum when an external additive is deposited in a concave portion. The conceptual diagram showing the mode of the discharge in the nip part of the charging roller which has a convex part originating in the resin particle which has electroconductivity, and a photosensitive drum is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Conductive elastic layer 3 Surface layer 4 Photosensitive drum 5 Charging roller 6 Developing roller 7 Printing medium 8 Transfer roller 9 Fixing part 10 Cleaning blade 11 Exposure 12 Pre-charging exposure apparatus 13 Elastic regulation blade 14 Toner supply roller 18 , 19, 20 Power supply 30 Toner seal 32 Cylindrical metal 33 Bearing

Claims (10)

A charging member for contact charging having a conductive substrate and a conductive surface layer;
The surface layer includes a binder resin and resin particles dispersed in the binder resin, and has a convex portion derived from the resin particle on the surface, and a ten-point average roughness Rzjis on the surface is 3 μm or more and 20 μm or less. And
The resin particles have an average particle diameter of 1 μm or more and 30 μm or less, and are composed of at least one selected from the group consisting of polyether ester, polyether amide, polyester amide, and polyether ester amide, and have conductivity. A charging member. A charging member for contact charging having a conductive substrate and a surface layer;
The surface layer includes a binder resin and resin particles dispersed in the binder resin, and has a convex portion derived from the resin particle on the surface, and a ten-point average roughness Rzjis on the surface is 3 μm or more and 20 μm or less. And
The resin particles have an average particle diameter of 1 μm or more and 30 μm or less, include a polymer having at least one selected from the structures of the following formulas (1) and (2) as a repeating structural unit, and have conductivity. A charging member.
_{- (CH 2 CH 2 O)} - (1)
_{- (CH (CH 3) CH} 2 O) - (2)   The polymer contained in the resin particles is selected from a copolymer consisting of epichlorohydrin and ethylene oxide, a copolymer consisting of epichlorohydrin, ethylene oxide and allyl glycidyl ether, and a copolymer consisting of ethylene oxide, propylene oxide and allyl glycidyl ether. The charging member according to claim 2, wherein the charging member is made of at least one kind. 4. The charging member according to claim 1, wherein the volume resistivity of the resin particles is 1 × 10 ⁶ Ω · cm or more and 1 × 10 ¹⁰ Ω · cm or less.   The charging member according to any one of claims 1 to 4, wherein the surface layer is a coating film formed of a coating material to which the binder resin and the resin particles are added.   The charging member according to claim 1, wherein the binder resin is a thermosetting resin.   The charging member according to claim 1, wherein the surface layer further contains conductive fine particles having an average particle diameter of 0.01 μm or more and 0.9 μm or less.   The charging member according to any one of claims 1 to 7 and the member to be charged are integrated at least, and the convex portion of the surface layer of the charging member causes a gap in the nip portion with the member to be charged, A process cartridge which is detachable from an electrophotographic image forming apparatus main body.   9. An electrophotographic image forming apparatus comprising at least the process cartridge according to claim 8, an exposure unit, and a development unit.   The electrophotographic image forming apparatus according to claim 9, wherein only the DC voltage is applied to the charging member to charge the member to be charged.

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