JP2005345783A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein charged particles used for charge stick on a photoreceptor surface, even after being charged to block exposure light, whereby a spotted image is generated. <P>SOLUTION: In the electrophotographic photoreceptor comprising at least a conductive support, a photosensitive layer and a protective layer, the surface shape of the protective layer is divided into undulating faces and rough faces at a cutoff value λc of 0.003 mm, the P-V value A of the undulating faces is 0.1-1.5 μm, the P-V value B of the rough faces is 0.001-0.8 μm, as well as A>B holds. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photosensitive member and a process cartridge, in particular, an electrophotographic photosensitive member having a protective layer, and a process cartridge having the photosensitive member.

  In recent years, electrophotographic photoreceptors using organic photoconductive materials have been studied and put into practical use in the market because of advantages such as safety, productivity, and low cost.

  In order to further increase the durability, improvement in the mechanical properties of the electrophotographic photosensitive member is required. For this reason, studies have been made to provide a protective layer containing a thermoplastic or curable resin as an upper layer of the photosensitive layer. The curable resin is suitable for extending the life because of its higher hardness. However, since the resin alone is basically electrically insulative, there are problems in electrophotographic characteristics such as sensitivity deterioration and residual potential, the film thickness cannot be increased, and high durability cannot be achieved. In order to solve the problem, it is conceivable that the protective layer contains a conductive substance. However, conductive materials are susceptible to the surrounding environment and lack stability. As a countermeasure, it has been proposed to treat the surface of the conductive material.

  In addition, it is conceivable to mix a charge transport material, but when a curable resin is used, a transport material having a desirable charge transport capability is not found.

  Further, corona charging, roller charging, and the like have been put to practical use in charging devices for electrophotographic apparatuses.

  In the corona charging, a charge ionized by applying a high voltage is deposited on the surface of the photoreceptor. Since the charge is not directly applied to the surface of the photoreceptor, the molecule is not cut and the molecular weight is not lowered.

  However, when a large amount of charged products such as ozone and Nox is generated and applied on the surface of the photoconductor when a high voltage is applied, the image of the cleaning member is deteriorated due to image flow in a humid environment or a decrease in slipperiness of the photoconductor surface. In some cases, blade reversal, chattering, etc. In addition, the releasability is lowered as the slipping property is lowered, and fusion occurs due to adhesion of an external toner additive or the like.

  Recently, roller charging has been used in many cases from the viewpoints of space saving and power saving. However, the surface of the photoconductor is charged by a discharge in a minute space between the surface of the photoconductor and the roller. Unlike corona charging, charge is applied to the surface of the photoconductor, resulting in lower molecular weight of molecules such as resin or charge transport material on the surface of the photoconductor. . Since charging is likely to concentrate on the thin part, the scratches are more easily scraped, which may affect the life of the photoreceptor.

In recent years, injection charging has been promoted. As an electrophotographic apparatus configuration, for example, a charging roller having a foam surface layer further includes charged conductive particles on the surface layer. Further, in the electrophotographic photoreceptor, a protective layer (charge injection layer) is provided on the photosensitive layer, and conductive fine particles are dispersed in the protective layer to provide a charge injection point (Japanese Patent Laid-Open No. 06-003921). Publication: Patent Document 1). For this reason, a voltage almost equal to the voltage applied to the charging means is charged to the photoconductor, so there is no reduction in molecular weight of the resin on the photoconductor surface, and there is little generation of charged products, which is advantageous for a cleaning-less process. There are advantages such as. However, there is a problem that charged conductive particles (hereinafter referred to as charged particles) used for charging adhere to the surface of the photosensitive member even after charging, thereby shielding exposure and generating a spot image.
Japanese Patent Laid-Open No. 06-003921

  As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by using an electrophotographic photosensitive member having a protective layer having a specific surface shape.

  That is, according to the present invention, in an electrophotographic photosensitive member having at least a photosensitive layer and a protective layer, the surface shape of the protective layer is separated into a wavy surface and a rough surface with a cut-off value λc: 0.003 mm. The V value was 0.1 to 1.5 μm, and the PV value of the roughness surface was 0.001 to 0.8 μm.

  By using the electrophotographic photosensitive member having the surface shape as described above, the amount of scraping is reduced and the life is improved by improving the scratch resistance. There is an effect, and a high-quality image can be obtained for a long time. Further, in the injection charging, the above-mentioned adhesion of charged particles is further reduced and a high quality image can be obtained.

  If the PV value of the wavy surface is 0.1 μm or less, scratches are likely to occur. When the thickness is 1.5 μm or more, the toner external additive adheres to the concave portion of the waviness and becomes a starting point of fusion. Injecting charging is not preferable because the charged particles are embedded in the unevenness of the surface, causing irregular reflection due to the refractive index and disturbing the latent image.

  When the PV value on the rough surface is 0.001 μm or less, the residual potential increases and the image density becomes thin. Text images are faint. In a low humidity environment, the residual potential further increases with continuous paper feeding. Flow may occur in a high humidity environment. In the injection charging, the charging ability is lowered. When the thickness is 0.8 μm or more, the character image is easily crushed in the image. The charging ability is reduced by continuous paper feeding, and black spots are generated on a white background in a high humidity environment. Injection charging produces a black spot image on a white background in a high humidity environment.

  More preferably, the PV values of the waviness surface and the roughness surface are 0.2 to 1.2 μm, 0.02 to 0.6 μm, and more preferably 0.4 to 1 μm. 0.05 to 0.5 μm.

  The protective layer simultaneously contains at least a binder resin, conductive fine particles and fine particles having inorganic insulating properties, and the inorganic insulating particles have an average particle diameter of 0.02 to 2 μm.

  In the inorganic insulating particles, when the average particle size is 0.02 μm or less, the strength of the protective layer does not increase and the abrasion does not decrease. When the particle size is 2 μm or more, contact of a member that comes into contact with the surface of the photosensitive member such as a charging member, a developing unit, a transfer member, or a cleaning member when half of the conductive particles are exposed on the surface of the protective layer due to the protective layer being scraped off. Is peeled off from the surface of the protective layer. The peeled marks can be the core of toner filming.

  In the injection charging, when the thickness is 2 μm or more, the charged particles are embedded in the irregularities on the surface, and irregular reflection occurs due to the refractive index, which is not preferable.

Further, the protective layer has an abundance ratio G (E / F) of the number of conductive particles E and the number F of inorganic insulating fine particles of 4 ≦ G ≦ 10 ⁵ . When E <4, the residual potential increases in a low humidity environment. In addition, a fine line image is reproduced finely. When E ≧ 10 ⁵ , adhesion of toner external additives, charged particles in injection charging, and the like increases. The thin line image is reproduced thick. Particularly in an electrophotographic apparatus using injection charging and cleaningless, the detailed reason is unknown by setting 4 ≦ G ≦ 10 ⁵ , but the charged particles easily adhere to the photoreceptor, and after transfer, The charged particles remaining on the surface of the photosensitive member are easily collected by an injection charging unit or a developing device. More effectively, preferably 10 <G <10 ⁴ , more preferably 50 <G <10 ³ .

  As described above, according to the present invention, the life can be extended by reducing the amount of scraping and improving the scratch resistance, and the adhesion of the external additive to the toner is reduced, which is effective for fusing. Thus, it is possible to provide an electrophotographic photosensitive member capable of obtaining the above image over a long period of time. Further, in the injection charging, it is possible to provide an electrophotographic photosensitive member that can further reduce the adhesion of the above-mentioned charged particles and obtain a high-quality image.

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

  As the binder resin used in the protective layer of the present invention, thermoplasticity includes, for example, polyethylene, polystyrene, methyl methacrylate, vinyl chloride, vinylidene chloride, vinyl acetate, cellulose, polyamide, polycarbonate, polyacetal, polyethylene terephthalate, polyimide. Examples include amide, polyimide, polyarylate, polyester, polyvinyl alcohol, polysulfone, acrylic nitrile, and methacryl. Examples of the curable resin include phenol, acrylic, epoxy, urethane, xylene, furan, urea, melamine, diallyl phthalate resin, and the like. “Hardened after formation of the protective layer” means, for example, that the protective layer is hardly dissolved even when wetted with an organic solvent.

  In the present invention, curable resins are preferable, and phenol, acrylic, epoxy, siloxane, and urethane resins are more preferable. More preferably, it is a phenol resin, and the resol type is most suitable among them.

  Examples of the conductive fine particles used in the present invention include aluminum, zinc, copper, chromium, nickel, silver, and stainless steel, or a product obtained by depositing these metals on the surface of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, indium oxide doped with tin, and tin oxide doped with antimony and tantalum. These can be used alone or in combination of two or more. When two or more types are used in combination, they may be simply mixed or in the form of a solid solution or fusion.

  Examples of the inorganic insulating particles used in the present invention include silicon nitride, aluminum nitride, alumina, magnesium oxide, zirconium oxide, barium sulfate, calcium oxide, and silica. These can be used alone or in combination of two or more.

  In the present invention, fluorine atom-containing resin fine particles may be included in order to improve the lubricity of the protective layer. Examples include ethylene tetrafluoride, ethylene trifluoride chloride resin, ethylene hexafluoride, propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and copolymers thereof. One or two or more are preferably selected as appropriate, and particularly preferred are tetrafluoroethylene resin and vinylidene fluoride resin. The molecular weight distribution and the average particle diameter of the resin particles can be appropriately selected and are not particularly limited.

  As a solvent for dispersing the coating material of the protective layer, the thermosetting resin is well dissolved, the charge transporting material is also well dissolved, the dispersibility of the conductive fine particles and the inorganic insulating fine particles is good, and the fluorine atom containing used in the present invention is also included. A solvent that does not adversely affect the charge transport layer in contact with the coating material of the protective layer is preferable because the resin particles have good compatibility and processability.

  Therefore, the solvents include alcohols such as methanol, ethanol and 2-propanol, ketones such as acetone and MEK, esters such as methyl acetate and ethyl acetate, ethers such as THF and dioxane, and aromatics such as toluene and xylene. Hydrocarbons, halogenated hydrocarbons such as chlorobenzene and dichloromethane can be used, and these may be used in combination.

  Among these, the most suitable solvents for the thermosetting resin are alcohols such as methanol, ethanol and 2-propanol.

  As a method for applying the protective layer of the present invention, general coating methods such as a dip coating method, a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, and a blade coating method can be used.

  If the protective layer of the present invention is too thin, the durability of the photoreceptor is impaired. If the protective layer is too thick, the residual potential due to the provision of the protective layer increases. Specifically, it should be in the range of 0.1 μm to 10 μm, and preferably in the range of 0.5 μm to 7 μm.

  In the present invention, an additive for an antioxidant may be added to the protective layer for the purpose of preventing deterioration of the surface layer due to adhesion of active substances such as ozone and NOx generated during charging.

  Next, the photosensitive layer will be described below.

  The photoreceptor of the present invention preferably has mainly a laminated structure. In the electrophotographic photoreceptor of FIG. 1a, a charge generation layer 3 and a charge transport layer 2 are provided in this order on a conductive support 4, and a protective layer 1 is further provided on the outermost surface.

  Further, as shown in FIGS. 1b and 1c, a binder layer 5 and an undercoat layer 6 for the purpose of preventing interference fringes may be provided between the conductive support and the charge generation layer.

  As the conductive support 4, the support itself can be conductive, for example, aluminum, aluminum alloy, stainless steel, etc. In addition, aluminum, aluminum alloy, indium oxide-tin oxide alloy, etc. can be used by vacuum deposition. The conductive support, plastic, and conductive fine particles (for example, carbon black, tin oxide, titanium oxide, silver particles, etc.) having a layer formed with a film are impregnated into plastic or paper together with an appropriate binder, conductive binder It is possible to use plastics having

  In addition, a binder layer (adhesive layer) having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer.

  The binder layer is formed to improve the adhesion of the photosensitive layer, improve coating properties, protect the support, cover defects on the support, improve charge injection from the support, and protect against electrical breakdown of the photosensitive layer. Is done. The binder layer can be formed of casein, polyvinyl alcohol, ethyl cellulose, ethylene-acrylic acid copolymer, polyamide, modified polyamide, polyurethane, gelatin, aluminum oxide, or the like. The thickness of the binding layer is preferably 5 μm or less, and more preferably 0.1 to 3 μm.

  Examples of the charge generating material used in the present invention include (1) azo pigments such as monoazo, disazo and trisazo, (2) phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, and (3) indigo materials such as indigo and thioindigo. Pigments, (4) perylene pigments such as perylene anhydride and perylene imide, (5) polycyclic quinone pigments such as anthraquinone and pyrenequinone, (6) squarylium dyes, (7) pyrylium salts and thiapyrylium salts ( 8) Triphenylmethane dyes, (9) inorganic substances such as selenium, selenium-tellurium, amorphous silicon, (10) quinacridone pigments, (11) azulenium salt pigments, (12) cyanine dyes, (13) xanthene dyes, (14) Quinoneimine dye, (15) styryl dye, (16) cadmium sulfide Such as arm and (17) zinc oxide.

  Examples of the binder resin used for the charge generation layer include polycarbonate resin, polyester resin, polyarylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, vinyl acetate resin, phenol resin, Examples of the resin include, but are not limited to, a silicone resin, a polysulfone resin, a styrene-butadiene copolymer resin, an alkyd resin, an epoxy resin, a urea resin, and a salted vinyl-vinyl acetate copolymer resin. These may be used alone, as a mixture or as a copolymer polymer, or one or more of them may be used.

  The solvent used in the charge generation layer coating material is selected from the solubility and dispersion stability of the resin and charge generation material used, and examples of the organic solvent include alcohols, sulfoxides, ketones, ethers, esters, fats. Group halogenated hydrocarbons or aromatic compounds can be used.

  The charge generation layer 3 is well dispersed by a method such as a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, and a roll mill together with the above-described charge generation material in a amount of 0.3 to 4 times the binder resin and solvent. It is formed by coating and drying. The thickness is preferably 5 μm or less, particularly in the range of 0.01 to 1 μm.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers or known charge generating substances may be added to the charge generation layer as necessary.

  The charge transport materials used include various triarylamine compounds, various hydrazone compounds, various styryl compounds, various stilbene compounds, various pyrazoline compounds, various oxazole compounds, various thiazol compounds, various triaryl compounds. -Lumethane compounds and the like.

  Examples of the binder resin used to form the charge transport layer 2 include acrylic resin, styrene resin, polyester, polycarbonate resin, polyarylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane resin, alkyd resin, and unsaturated resin. A resin selected from resins and the like is preferable. Particularly preferred resins include polymethyl methacrylate, polystyrene, styrene-acrylonitrile copolymer, polycarbonate resin or diallyl phthalate resin.

  The charge transport layer 2 is generally formed by dissolving the charge transport material and the binder resin in a solvent and applying them. The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 2. Solvents include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, and chlorinated hydrocarbons such as chlorobenzene, chloroform and carbon tetrachloride. . When this solution is applied, for example, a coating method such as a dip coating method, a spray coating method, or a spinner coating method can be used, and drying is performed at a temperature in the range of 10 ° C to 200 ° C, preferably 20 ° C to 150 ° C. And for 5 minutes to 5 hours, preferably 10 minutes to 2 hours, can be carried out under blast drying or static drying.

  The charge transport layer is electrically connected to the charge generation layer described above, receives charge carriers injected from the charge generation layer in the presence of an electric field, and transports these charge carriers to the interface with the protective layer. It has a function to do. Since this charge transport layer has a limit to transport charge carriers, the film thickness cannot be increased more than necessary, but a range of 5 to 40 μm, particularly 7 to 30 μm is preferable.

  Furthermore, an antioxidant, an ultraviolet absorber, a plasticizer, or a known charge transport material can be added to the charge transport layer as necessary.

  FIG. 2 shows a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.

  In FIG. 2, reference numeral 11 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is rotationally driven around a shaft 12 in a direction indicated by an arrow at a predetermined peripheral speed. In the rotation process, the electrophotographic photosensitive member 11 is uniformly charged at a predetermined positive or negative potential on its peripheral surface by the primary charging unit 13, and then from an exposure unit (not shown) such as slit exposure or laser beam scanning exposure. The exposure light 14 whose intensity is modulated corresponding to the time-series electric digital image signal of the target image information to be output is received. In this way, electrostatic latent images corresponding to target image information are sequentially formed on the peripheral surface of the electrophotographic photosensitive member 11.

  The formed electrostatic latent image is then developed with toner by the developing means 15 and taken out from a paper feeding unit (not shown) between the electrophotographic photosensitive member 11 and the transfer means 16 in synchronization with the rotation of the electrophotographic photosensitive member 11. The toner image formed and supported on the surface of the electrophotographic photosensitive member 11 is sequentially transferred by the transfer unit 16 to the transferred transfer material 17.

  The transfer material 17 that has received the transfer of the toner image is separated from the surface of the electrophotographic photosensitive member, introduced into the image fixing means 18, and subjected to image fixing to be printed out as an image formed product (print, copy). .

  After the image is transferred, the surface of the electrophotographic photosensitive member 11 is cleaned by removing the transfer residual toner by the cleaning unit 19, and is further subjected to charge removal processing by the pre-exposure light 20 from the pre-exposure unit (not shown). Used repeatedly for image formation. When the primary charging unit 13 is a contact charging unit using a charging roller or the like, pre-exposure is not always necessary.

  In the present invention, a plurality of components such as the electrophotographic photosensitive member 11, the primary charging unit 13, the developing unit 15 and the cleaning unit 19 are housed in a container and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 13, the developing unit 15, and the cleaning unit 19 is integrally supported together with the electrophotographic photosensitive member 11 to form a cartridge, and is attached to and detached from the apparatus main body using a guide unit 22 such as a rail of the apparatus main body. A flexible process cartridge 21 can be obtained.

  Further, when the electrophotographic apparatus is a copying machine or a printer, the exposure light 14 is reflected or transmitted light from the original, or the original is read by a sensor, converted into a signal, and a laser beam scanning performed in accordance with this signal. The light emitted by driving the LED array or the liquid crystal shutter array.

  The electrophotographic photosensitive member of the present invention can be used not only for electrophotographic copying machines but also widely applicable to electrophotographic application fields such as laser printers, CRT printers, LED printers, FAX printers, liquid crystal printers, and laser plate making. It is.

  The injection charging apparatus of the present invention will be described below.

FIG. 3 is a schematic configuration diagram of an image recording apparatus using the charging device according to the present invention.
The image recording apparatus of the present embodiment is a direct injection charging type laser printer (recording apparatus) using a transfer type electrophotographic process.

(L) Schematic Configuration of Printer 1 is an image carrier, and in this embodiment, is a rotating drum type negative OPC photosensitive member (negative photosensitive member, hereinafter referred to as a photosensitive drum) of φ30 mm. The photosensitive drum 1 is driven to rotate at a constant speed of 94 mm / sec (= process speed PS, printing speed) in the clockwise direction of the arrow.

  The charging device includes a charging roller 2 and a charged conductive particle supplier 3.

  The charging roller 2 includes charged conductive particles M (conductive particles as charged particles), a medium resistance layer 2b and a cored bar 2a as particle carriers. The charging roller 2 comes into contact with the photosensitive drum 1 with a predetermined penetration amount to form a contact portion n.

  The charging roller 2 is rotationally driven in the opposite direction (counter) to the rotation direction of the photosensitive drum 1 at the charging contact portion n, and contacts the surface of the photosensitive drum 1 with a speed difference. In addition, when a printer image is recorded, a predetermined charging bias is applied to the charging roller 2 from a charging bias application power source S1, whereby the peripheral surface of the photosensitive drum 1 is uniformly contact-charged to a predetermined polarity and potential by a direct injection charging method. It is processed. In this embodiment, a DC voltage of −700 V was applied as an applied bias by the applied power source of S1.

  The charged conductive particles adhere to the photosensitive drum along with charging. Accordingly, the charged conductive particle supplier 3 is required to compensate for this. The particles are applied by stirring the charged conductive particles M stored in the housing container with stirring blades and supplying them to the conductive elastic roller 2a.

  Then, excessive charged conductive particles corresponding to the target coating amount are scraped off with a fur brush, and the charged conductive particles are applied. The control of the coating amount can be adjusted at any time according to the rotation speed of the fur brush.

  The charging device and direct injection charging will be described in detail in another section.

  Reference numeral 4 denotes a laser beam scanner (exposure device) including a laser diode, a polygon mirror, and the like. The laser beam scanner 4 outputs a laser beam whose intensity is modulated in accordance with the time-series digital image signal of the target image information, and scans and exposes the uniformly charged surface of the rotating photosensitive drum 1 with the laser beam.

  By this scanning exposure L, an electrostatic latent image corresponding to target image information is formed on the surface of the rotary photosensitive drum l.

  The developing device 5 holds a developer composed of a magnetic carrier and a nonmagnetic toner, and coats a certain amount on the sleeve. The toner has a certain triboelectric charge due to sliding with the carrier, and develops an electrostatic latent image on the photosensitive drum in the developing region a by a bias applied between the sleeve and the drum.

  Reference numeral 6 denotes a medium resistance transfer roller as a contact transfer means, which is brought into pressure contact with the photosensitive drum 1 to form a transfer nip portion b. A transfer material P as a recording medium is fed to the transfer nip b from a paper feed unit (not shown) at a predetermined timing, and a predetermined transfer bias voltage is applied to the transfer roller 6 from a transfer bias application power source S3. As a result, the toner image on the photosensitive drum l side is sequentially transferred onto the surface of the transfer material P that is coated on the transfer nip b.

The transfer roller 6 used in this embodiment has a roller resistance value of 5 × 10 ⁸ Ω, in which a medium resistance foam layer 6b is formed on a cored bar 6a, and is transferred by applying a voltage of +2.0 kV to the cored bar. Was done. The transfer material P introduced into the transfer nip portion b is nipped and conveyed by the transfer nip portion b, and the toner images formed and supported on the surface of the rotary photosensitive drum l on the surface side are successively subjected to electrostatic force and pressing force. Will be transcribed.

  Reference numeral 7 denotes a fixing device such as a heat fixing method. The transfer material P that has been fed to the transfer nip b and has received the transfer of the toner image on the photosensitive drum l side is separated from the surface of the rotating photosensitive drum l and introduced into the fixing device 7 to receive the toner image. Then, it is discharged out of the apparatus as an image formed product (print copy).

  8 is a photosensitive drum cleaning, which collects toner remaining on the photosensitive member. The photosensitive drum is again charged by the charging device and used for image formation.

  Next, the main members will be described in detail individually.

(2) Photoconductor with charge injection layer In the present invention, the photosensitive drum 1a is used.

(3) Charging roller 2
The charging roller 2 in this embodiment is configured by forming a middle resistance layer 2b of rubber or foam on a core metal 2a, and further carrying charged conductive particles M on the surface layer.

  The middle resistance layer 2b is formulated with a resin (for example, urethane), conductive particles (for example, carbon black), a sulfurizing agent, a foaming agent, and the like, and is formed in a roller shape on the core metal 2a. Thereafter, the surface was polished.

  The charging roller in the present invention is particularly different from the charging roller for discharge generally used in the following points.

  1. Surface structure and roughness characteristics for carrying high-density charged conductive particles on the surface layer.

2. Resistance characteristics required for direct charging. (Volume resistance, surface resistance)
(3) -1, Surface Structure and Roughness Characteristics Conventionally, the roller surface by discharge is flat, the average roughness Ra of the surface is sub-μm or less, and the roller hardness is high. In charging using discharge, a discharge phenomenon occurs in a gap of several tens of μm that is slightly apart from the contact portion between the roller and the drum. When unevenness exists on the roller and drum surfaces, the electric field strength is partially different, so that the discharge phenomenon becomes unstable and charging unevenness occurs. Therefore, the conventional charging roller requires a flat and high hardness surface.

  So why does the charging roller for injection do not allow charging? In the surface structure as described above, it looks like it is in close contact with the drum, but it is almost in the sense of micro contact at the molecular level required for charge injection. It is not.

  On the other hand, the conductive elastic roller of the present invention is required to have a certain degree of roughness because it needs to carry charged conductive particles at a high density. The average roughness Ra is preferably 1 μm to 500 μm. If it is 1 μm or less, the surface area for supporting the particles is insufficient, and if an insulator (for example, toner) or the like adheres to the roller surface layer, the periphery cannot contact the drum, and the charging performance decreases. On the other hand, when the thickness is 500 μm or more, the unevenness on the roller surface reduces the in-plane charging uniformity of the member to be charged. In this example, Ra was 40 μm.

  For the measurement of the average roughness Ra, the surface shape measurement microscopes VF-7500 and VF7510 manufactured by Keyence Corporation were used, and the shape of the roller surface and Ra were measured in a non-contact manner using the objective lens 1250 to 2500 times.

(3) -2, Resistance Characteristics In a conventional charging roller using discharge, a low resistance base layer is formed on a core metal, and then the surface is covered with a high resistance layer. The roller charging due to the discharge has a high applied voltage, and if there is a pinhole (exposed substrate due to film damage), a voltage drop and a charging failure occur around it. Therefore, it must be 10 ¹¹ Ω □ or more.

On the other hand, in the direct injection charging system of the present invention, it is not necessary to increase the resistance of the surface layer in order to enable charging with a low voltage, and the roller can be configured as a single layer. Rather, it is necessary that the surface resistance of the charging roller is 10 ⁴ to 10 ¹⁰ Ω in direct injection charging. When it is 10 ¹⁰ or more, the uniformity in the charged surface is lowered, and unevenness due to the rubbing of the roller appears as a streak in the halftone image, and the image quality is lowered. On the other hand, in the case of 10 ⁴ or less results in a voltage drop of around by the drum pinholes even injection charging.

Further, the volume resistance is preferably in the range of 10 ⁴ to 10 ⁷ Ω. For 10 ⁴ or less, it tends to occur a voltage drop of the power supply due to pinholes leak. On the other hand, when it is 10 ⁷ or more, the current required for charging cannot be secured, and the charging voltage is lowered.

The surface resistance and volume resistance of the charging roller used in this example were 10 ⁷ and 10 ⁶ Ω.

  The roller resistance was measured by the following procedure. A schematic diagram of the configuration at the time of measurement is shown in FIG. The roller resistance was measured by applying an electrode to an insulator drum 93 having an outer diameter of 30 mm so that the core metal 2a of the charging roller 2 was loaded with a total pressure of 1 kg. For the electrodes, a guard electrode 91 was arranged around the main electrode 92, and the measurement was performed according to the wiring diagram shown in FIG. The distance between the main electrode and the guard electrode was adjusted to about the thickness of the elastic layer 2b, and the main electrode secured a sufficient width with respect to the guard electrode. The measurement was performed by applying +100 V from the power source S4 to the main electrode, measuring the current flowing through the ammeters Av and As, and measuring the volume resistance and the surface resistance, respectively.

  As described above, the charging roller of the present invention has the following features: 1. Surface structure roughness characteristics for carrying high-density charged conductive particles on the surface layer; 2, resistance characteristics required for direct charging (volume resistance, surface resistance )is required.

Other roller characteristics In the direct injection charging system, it is important that the charging member functions as a flexible electrode. The magnetic brush is realized by the flexibility of the magnetic particle layer itself. In the charging device, this is achieved by adjusting the elastic characteristics of the intermediate resistance layer 2b. A preferred range of Asker C hardness is 15 to 50 degrees. More preferably, it is 25 to 40 degrees. If it is too high, the necessary penetration amount cannot be obtained and the charging contact portion n cannot be secured between the charged body and the charging performance is lowered. Further, since the contact of the substance at the molecular level cannot be obtained, the contact with the surroundings is hindered by the entry of foreign substances. On the other hand, if the hardness is too low, the shape is not stable, so that the contact pressure with the object to be charged becomes uneven, resulting in uneven charging. Alternatively, charging failure occurs due to permanent deformation distortion of the roller due to long-term standing.

  In this embodiment, a roller having Asker C hardness of 22 degrees was used. Further, the charging roller 2 is disposed at an intrusion amount of 0.3 mm with respect to the photosensitive drum 1, and in this embodiment, a charging contact portion n of about 2 mm is formed.

(3) -4 Charging roller material, structure, dimensions As the material of the charging roller 2, conductive materials such as EPDM, urethane, NBR, silicone rubber, and carbon black or metal oxide for adjusting resistance to IR, etc. Examples include dispersed rubber materials. It is also possible to adjust the resistance using an ion conductive material without dispersing the conductive substance. Thereafter, molding is performed by adjusting the surface roughness, polishing, or the like, if necessary. Moreover, the structure by the function-separated multiple layer is also possible.

  However, a porous structure is more preferable as the form of the roller. This is also advantageous in terms of manufacturing in that the aforementioned surface roughness can be obtained simultaneously with the molding of the roller. The cell diameter of the foam is suitably 1 to 500 μm. After foam molding, the surface of the porous body is exposed by polishing the surface, and the surface structure having the above-described roughness can be created.

  Finally, an elastic body layer (layer thickness: 3 mm) having a porous body surface is formed on a core metal having a diameter of 6 mm and a longitudinal length of 240 mm, and a charging roller 2 having an outer diameter of 12 mm and an elastic body layer having a longitudinal length of 220 mm is produced. did.

  The charging roller 2 is disposed at an intrusion amount of 0.3 mm with respect to the photosensitive drum 1 as a member to be charged, and in this embodiment, a charging contact portion n of about 2 mm is formed.

(4) Charged conductive particles m
In this example, conductive zinc oxide having a specific resistance of 10 ⁶ Ω · cm and an average average particle size of 3 μm was used as the charged conductive particles. The charged conductive particles m are accommodated in a particle supplier.

  As the material of the conductive particles m, various conductive particles such as conductive inorganic particles such as other metal oxides and mixtures with organic substances, or those obtained by subjecting them to a surface treatment can be used. In addition, since the charged particles in the present invention do not need to be magnetically constrained, they need not have magnetism.

The particle resistance needs to be 10 ¹² Ω · cm or less, preferably 10 ¹⁰ Ω · cm or less as the specific resistance in order to transfer charges through particles.

The resistance was measured by the tablet method and normalized. That is, about 0.5 g of conductive particles are placed in a cylinder with a bottom area of 2.26 cm ^{2 and} a pressure of 15 V is applied to the upper and lower electrodes and simultaneously a voltage of 100 V is applied to measure the resistance value. Calculated.

  The average particle size is desirably 10 μm or less in order to obtain high charging efficiency and charging uniformity exceeding that of the magnetic brush charger. In the present invention, the average particle diameter in the case where the particles constitute an aggregate is defined as the average average particle diameter as the aggregate. For the measurement of the average particle size, 100 or more samples were extracted from observation with an electron microscope, and the volume average particle size distribution was calculated with the maximum horizontal chord length and determined with the 50% average average particle size.

  There is no problem that the conductive particles exist not only in the state of primary particles but also in the state of aggregation of secondary particles. In any aggregation state, the form is not important as long as the function as the conductive particles can be realized as an aggregate.

  The conductive particles are desirably white or nearly transparent so as not to hinder latent image exposure, particularly when used for charging a photoreceptor. Further, considering that the conductive particles are partially transferred from the photosensitive member to the recording material P, it is desirable that the color recording is colorless or white, and also in order to prevent light scattering by the particles during image exposure. It is desirable that the average particle size is not more than the constituent pixel size, and more preferably not more than the toner average particle size. As a lower limit of the average particle diameter, 10 nm is considered to be the limit as a stable particle.

(5) Conductive particle carrying amount and coverage ratio In the present invention, the charging performance is improved by reducing the average particle diameter of the charged particles in particle charging, but the dropping of the particles to the drum becomes remarkable. Since the force that can hold the particles on the roller is a weak adhesion force, it is difficult to restrain the particles even if many particles are supplied. Reduce the effects of image defects. Therefore, ideally, it is desirable to apply more evenly on the roller surface layer, but in practice it is possible to reduce the amount of adhering particles at a harmful level by ensuring the chargeability by adjusting the loading amount. It becomes.

The amount of magnetic conductive particles supported in a conventional magnetic brush charger is approximately 200 mg / cm ² , whereas the nonmagnetic conductive particles of the present invention are 50 mg or less. More preferable results are 10 mg / cm ² or less. On the other hand, the minimum supported amount is 0.1 mg / cm ^{2 because} it is necessary to ensure charging performance.

That is, it is desirable that the supported amount is in the range of 0.1 to 50 mg / cm ² , more preferably 0.1 to 10 mg / cm ² .

  Details will be described later in Examples.

  The carrying amount was adjusted by adjusting the rotation speed of the fur brush of the particle supplier 3. The higher the brush speed, the lower the particle loading can be set. Further, adjustments were made as necessary depending on the rotation speed of the stirring blade, the density of the fur brush, and the like.

(6) Developing device 5
The developing device 5 is a two-component developing device. The configuration will be described in detail.

  The developing device is disposed so as to face the photosensitive drum, and the inside thereof is divided into a first chamber (developing chamber) 58a and a second chamber (stirring chamber) 58b by a partition wall 57 extending in the vertical direction. . A non-magnetic developing sleeve 51 that rotates in the direction of the arrow is disposed in the opening of the first chamber so as to face the photosensitive drum 1, and a magnet 52 is fixedly disposed in the developing sleeve 51. The developing sleeve 51 carries and conveys a layer of a two-component developer (including a magnetic carrier and a non-magnetic toner) whose layer thickness is regulated by a blade 59, and the developer is transferred to the photosensitive drum 1 in a developing area a facing the photosensitive drum 1. Supply and develop electrostatic latent image. A developing bias voltage having a rectangular wave in which a DC voltage is superimposed on an AC voltage is applied to the developing sleeve 51 from the power source S2.

  Developer stirring screws 53a and 53b are arranged in the first chamber 58a and the second chamber 58b, respectively. The screw 53a stirs and conveys the developer in the first chamber 58a, and the screw 53b develops toner already supplied in the developing unit with toner supplied by rotation of the conveying screw 56 from a toner discharge port of a toner supply tank (not shown). The toner 58b is agitated and conveyed to make the toner density uniform. The partition wall 57 is formed with a developer passage (not shown) that allows the first chamber and the second chamber to communicate with each other at the front and back end portions in FIG. 1, and transports the screws 53a and 53b. Due to the force, the developer in the first chamber, in which the toner is consumed due to the development and the toner concentration is lowered, moves from one passage to the second chamber, and the developer whose toner concentration is recovered in the second chamber passes through the first passage from the other passage. It is configured to move indoors.

  On the other hand, the developer concentration control device adjusts the magnetic permeability of the developer by monitoring it with a magnetic sensor. The magnetic permeability varies depending on the mixing ratio due to the difference in magnetic permeability between the toner and the developing carrier. Therefore, toner replenishment is controlled by comparing the output of the magnetic sensor measured in advance with the current output, and the ratio of toner in the developing chamber is kept constant.

Developer The developer is a two-component developer composed of a nonmagnetic toner that is frictionally charged to a negative and magnetic carrier particles that are positively charged. The mixing ratio of the developer was set to 5% of the nonmagnetic toner by weight.

  a) Toner t: The non-magnetic toner t is prepared by mixing a binder resin, a pigment, and a charge control agent, kneading, pulverizing, and classifying, and further adding a fluidizing agent as an external additive. It has been done. The average average particle diameter (D4) of the toner was 8 μm.

b) Carrier Cd: The magnetic carrier is composed of ferrite particles, the average average particle diameter is 50 μm, and the resistance value is 10 ⁸ Ω · cm or more.

(Embodiment 2)
FIG. 4 is a schematic configuration diagram showing an image recording apparatus according to a second embodiment using the charging device of the present invention. The image recording apparatus of the present embodiment is a laser printer (recording apparatus) using a transfer type electrophotographic process, a direct injection charging system, and a toner recycling process (cleanerless system). The same points as in the first embodiment are omitted, and different points are described.

(L) Overall Schematic Configuration of Printer The charging device does not include a charged conductive particle supplier. The conductive particles are added to the developer and accumulated, and are supplied to the charging roller via the photosensitive drum together with the development of the toner.

  Reference numeral 60 denotes a developing device. The electrostatic latent image on the surface of the rotating photosensitive drum l is developed as a toner image at the development site a by the developing device 60. In the developing device 60, a mixed agent tm obtained by adding conductive particles m to the developer t is provided.

  The printer of this embodiment is a toner recycling process, and the transfer residual toner remaining on the surface of the photosensitive drum 1 after image transfer is not removed by a dedicated cleaner (cleaning device), and the counter rotation is performed as the photosensitive drum 1 rotates. As the toner is temporarily collected by the charging roller and circulates around the outer circumference of the roller, the reversed toner charge is normalized and sequentially discharged to the photosensitive drum to reach the development site a. Is done.

(2) Charging roller 2
Except that the charged conductive particle feeder is not provided, the configuration of the first embodiment is applied.

(3) Developing device 60
The developing device 60 of this embodiment is a reversal developing device using a one-component magnetic toner (negative toner) as the developer t. In the developing device, a mixture tm of developer (toner) t and conductive particles m is provided.

  Reference numeral 60a denotes a non-magnetic rotating developing sleeve as a developer carrying member including a magnet roll 60b. The toner t in the pre-development mixture tm provided in the developing container 60e is conveyed on the rotating developing sleeve 60a. In the process, the regulation blade 60c undergoes layer thickness regulation and charge application. A stirring member 60d circulates the toner in the container and sequentially conveys the toner around the sleeve.

  The toner t coated on the rotating developing sleeve 5a is conveyed to a developing portion (developing region) a which is a portion opposite to the photosensitive drum 1 and the sleeve 5a by the rotation of the sleeve 5a. A developing bias voltage is applied to the sleeve 60a from a developing bias applying power source S5.

  In this embodiment, the developing bias voltage is a superimposed voltage of a DC voltage and an AC voltage.

  As a result, the electrostatic latent image on the photosensitive drum l side is reversely developed with the toner t.

  (3) -a) Toner t: A one-component magnetic toner t as a developer is prepared by mixing binder resin, magnetic particles, and charge control agent, and kneading, pulverizing, and classifying, and further conducting particles. m and a fluidizing agent are added as external additives. The average average particle diameter (D4) of the toner was 7 μm.

  (3) -b) Conductive particle m: According to the first embodiment.

(4) Amount of Conductive Particles Supported and Coverage In the present embodiment, since the toner recycling configuration is used, more toner than the first embodiment contaminates the charging roller surface. The toner has a resistance value of 10 ¹³ Ω · cm or more in order to maintain the electric charge due to frictional charging on the surface. Therefore, when the roller is contaminated with toner, the particle resistance carried on the roller is increased and the charging performance is lowered. Even if the resistance of the charged conductive particles is low, the resistance of the powder carried due to the mixing of the toner is increased and the charging property is impaired. Therefore, even if the supported amount is 0.1 to 100 mg / cm ² according to the first embodiment, and preferably 0.1 to 10, the toner may be included in the component, and the charging performance is naturally deteriorated. . In this case, the resistance of the supported particles increases and the situation can be grasped. That is, in an actual use state, resistance measurement is performed on the particles (including contaminants such as toner and paper powder) carried on the charging roller by the method described above, and the value is 10 ⁻¹ to 10 ¹² . Preferably it is necessary that a ^{10 10.}

  Furthermore, in order to grasp the effective abundance in charging of the charged conductive particles, it is further important to adjust the coverage of the conductive particles. Since the charged conductive particles are white, they can be distinguished from the magnetic toner black. A region exhibiting white in observation with a microscope is obtained as an area ratio. When the coverage is 0.1 or less, it is important to keep the coverage of the charged conductive particles in the range of 0.2 to 1 because the charging performance is insufficient even if the peripheral speed of the charging roller is increased. .

  In addition, the amount of loading was basically adjusted by adjusting the amount of charged conductive particles added to the developer. Further, as necessary, adjustment was performed by bringing an elastic blade into contact with a part of the outer periphery of the charging roller. By abutting the member, there is an effect of normalizing the frictional charging polarity of the toner, and the amount of particles carried on the roller can be adjusted.

(Embodiment 3)
This embodiment shown in FIG. 5 is an image forming apparatus in the case where an image forming apparatus according to Embodiment 1 is combined with a reversal developing device using a one-component magnetic developer according to Embodiment 2 instead of a two-component developer. is there. Details of the individual devices are the same as those in the first and second embodiments.

  Embodiments of the present invention will be described below.

<Toner>
The toner of the present invention is premised on the mass average average particle size being 3 μm or more and 12 μm or less. When the thickness is less than 3 μm, transferability is deteriorated and fog is deteriorated. The addition of the metal compound fine particles shown below can be improved to some extent. However, for example, in the simultaneous development cleaning employing a direct injection charging mechanism, a decrease in charging property cannot be avoided. On the other hand, when the mass average average particle diameter exceeds 12 μm, the resolution on the image is lowered, and improvement from the system is difficult.

  In this example, the mass average average particle diameter of the toner was determined as follows. Using Coulter Multisizer (manufactured by Coulter), an interface (manufactured by Nikka) and a PC9801 personal computer (manufactured by NEC) that output number distribution and volume distribution are connected, and the electrolyte is 1% NaCl using first grade sodium chloride. Adjust the aqueous solution. As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample is suspended is dispersed for about 1 to 3 minutes using an ultrasonic disperser, and the volume distribution is determined by measuring the volume and number of toner particles of 2 μm or more using the 100 μm aperture as the aperture by the Coulter Multisizer. And the number distribution were calculated. Then, the volume-based mass average average particle diameter (D4) obtained from the volume distribution in the present invention was obtained.

The toner of the present invention has substantially non-magnetic metal compound fine particles, and the metal compound fine particles have a specific surface area of 5E5 (cm ² / cm ³ ) or more and 100E5 or less.

  For example, when magnetic metal compound fine particles are added to a magnetic toner, the fine particles released from the toner often adhere to the toner carrier and become contaminated, which adversely affects the triboelectric charging characteristics of the toner and the image characteristics as they are. There is a risk of affecting.

  Next, the contact density between the metal compound fine particles and the toner particles and between the metal compound fine particles and the charging member surface will be considered.

  The number of contacts is 1 when a particle that is generally assumed to be spherical contacts a member that is assumed to be approximately planar. This also applies to the contact between the metal compound fine particles and the charging member or toner particles. Therefore, in order to increase the number of contact points with the toner particles and the charging member, if many irregularities are formed on the surface of the material, the number of contact portions increases, and the number of contact points can be increased. However, for example, forming a large number of irregularities on the surface of the toner particles is not preferable in terms of frictional charging characteristics. On the other hand, if irregularities are formed on the surface of the metal compound fine particles, the contact point with not only the toner particles but also the charging member is increased.

  That is, forming a large number of irregularities on the surface of the metal compound fine particles is a technique applicable to a wide range without requiring special specifications for the printer body and the toner to be used.

As an index of the number of irregularities on the particle surface, the specific surface area of the particle powder is usually used. However, the specific surface area generally used is the surface area per unit weight, as can be seen from the unit, cm ² / g, and it is not easy to compare or optimize with materials having different specific gravities in the discussion using this value. .

Therefore, the present inventors adopted cm ² / cm ³ units, which are physical properties corresponding to the surface area per fine particle, as the specific surface area, the number of contact points between the metal compound fine particles, the toner and the charging member, image characteristics, and The relationship with the charging property was studied earnestly.

As a result, in the image forming method including the contact charging step, when the specific surface area of the metal compound fine particles contained in the toner used is 5E5 (cm ² / cm ³ ) or more and 100E5 or less, the chargeability and image characteristics are greatly improved. In particular, in an image forming method including a direct injection charging mechanism, it has been found that good chargeability can be maintained even if the charging member is contaminated. This is believed to be due to the effect of increasing the number of contact points between the metal compound fine particles, the toner and the charging member. Preferably, the chargeability and image characteristics are further improved by setting the pressure to 10E5 (cm ² / cm3) or more and 80E5 or less, more preferably 12E5 (cm ² / cm ³ ) to 40E5 or less.

  Here, the specific surface area of the metal compound fine particles was determined as follows.

First, in accordance with the BET method, nitrogen gas is adsorbed on the surface of the material using a specific surface area measuring device “Gemini 2375 Ver. 5.0” (manufactured by Shimadzu Corporation), and the BET specific surface area (cm ²⁾ using the BET multipoint method. / G).

Next, the true density (g / cm ³ ) is obtained using a dry automatic densimeter “Acpyc 1330” (manufactured by Shimadzu Corporation). At this time, a 10 cm ³ sample container is used, and as a sample pretreatment, helium gas purge is performed 10 times at a maximum pressure of 19.5 psig. After that, as a pressure equilibrium judgment value as to whether or not the pressure in the container has reached equilibrium, the pressure fluctuation in the sample chamber is 0.0050 / min as a guide. Start and automatically measure true density. The measurement is performed 5 times, the average value is obtained, and the true density is obtained.

  Here, the specific surface area of the powder is obtained as follows.

Specific surface area (cm ² / cm ³ ) = BET specific surface area (cm ² / g) × true density (g / cm ³ )
Furthermore, the metal compound fine particles are conductive fine particles having a volume-based median diameter (D ₅₀ ) of 0.4 μm or more and 4.0 μm or less and less than the mass average average particle diameter of the toner.

In general, the adhesion force due to the interaction between particles is stronger as the difference in average particle size between particles is larger. One of the actions expected for the metal compound fine particles according to the present invention is to improve the triboelectric charging characteristics by contact with the toner, and the action is difficult if the metal compound fine particles and the toner particles are strongly adhered. Become. The toner of the present invention has a mass average average particle diameter of 3.0 μm to 12.0 μm, and the appropriate D ₅₀ of the metal compound fine particles is 0.4 μm or more. D ₅₀ is less than 0.4μm metal compound fine particles is difficult to separate from the toner particles, since not expected to be improved in the frictional charging characteristics, for example, sufficient image density can not be obtained.

On the other hand, the interaction between the toner when D ₅₀ is increased is weakened, the effect of improving the friction charging properties reduced. When a metal compound D ₅₀ of the particles is on the mass average mean particle diameter or less of the toner, in addition to the effect of the interaction is hardly observed, come to rather inhibit the movement of the toner under development field, fog deteriorating Or the resolution decreases. More preferred _{D 50} is 0.5μm or more 3.5μm or less.

In this sense, it is preferable that the number of fine particles having a small average particle diameter is smaller in the particle size distribution of the metal compound fine particles. It may be used D ₁₀ based on volume as an index of the distribution of fines side in the particle size distribution, more preferably at least 0.3μm as the D _10, more preferably more than 0.4 .mu.m. Preferably lesser also large particles having an average particle diameter in the same manner, by using the D ₉₀ as an indication of the distribution of coarse powder side, D ₉₀ is said less and more preferably 4 [mu].

Here, _D 10 of the metal compound fine _{particles, D 50,} D _90, is measured as follows.

The average particle size of 0.04~2000μm the measurement range to the laser diffraction particle size distribution measuring apparatus "LS-230 Model" (manufactured by Beckman Coulter, Inc.) is attached to liquid module, particle D ₁₀ of the particle size distribution on a volume basis obtained , D ₅₀ , D ₉₀ are calculated. In the measurement, about 10 mg of particles are added to 10 ml of methanol and dispersed for 2 minutes with an ultrasonic disperser, and then measured under the conditions of a measurement time of 90 seconds and a single measurement.

  The preferred volume resistance of the metal compound fine particles according to the present invention is 1E-1 to 1E9 Ωcm. If it exceeds 1E9 Ωcm, the effect of improving the charging property is not expected when used in an image forming method including a contact charging step. On the other hand, if it is less than 1E-1 Ωcm, the triboelectric charging characteristics of the toner under high humidity are hindered, and in addition to deterioration in developability, fogging and transferability are deteriorated. As a result, the effect of improving the chargeability due to the large specific surface area cannot be seen.

  Here, the resistance of the particles is measured as follows.

A cylindrical metal cell is filled with a sample, electrodes are arranged up and down so as to contact the sample, and a load of 7 kgf / cm ² is applied to the upper electrode. In this state, a voltage V is applied between the electrodes, and the resistance (volume resistivity RV) of the present invention is measured from the current I (A) flowing at that time. At this time, when the electrode area is Scm ² and the sample thickness is M (cm), RV (Ωcm) = 100 V × Scm ² / I (A) / M (cm).

In the present invention, the contact area between the electrode and the sample was 2.26 cm ^2, and the measurement was performed at a voltage V = 100V.

  Examples of the metal compound fine particles in the present invention include metal fine powders such as copper, gold, silver, aluminum and nickel; zinc oxide, titanium oxide, tin oxide, aluminum oxide, indium oxide, silicon oxide, magnesium oxide, barium oxide, Metal oxides such as molybdenum oxide, iron oxide, and tungsten oxide; metal compounds such as molybdenum sulfide, cadmium sulfide, and potassium titanate, or conductive fine powders of these composite oxides can be used.

  Among these, the inclusion of at least one oxide selected from zinc oxide, tin oxide, and titanium oxide allows the resistance of the metal compound fine particles to be set low, is white or light, and is transferred onto the transfer material. It is preferable in that the metal compound fine particles are not noticeable as fog.

  Further, for the purpose of controlling the resistance value of the metal compound fine particles, metal oxide fine particles containing an element such as antimony or aluminum, fine particles having a conductive material on the surface, and the like can be used as the metal compound fine particles. For example, zinc oxide fine particles containing an aluminum element, tin oxide fine particles containing an antimony element, and the like.

  However, resistance control by introducing an antimony element is generally not preferred because the blue-black color of the powder increases.

  In the experimental example of the present invention, a direct injection charging mechanism and a cleanerless are combined, and an organic photoreceptor containing conductive tin oxide as a trap agent for injection charge in the surface protective layer is used. The higher the content of tin oxide in the metal compound fine particles added to the toner, the better the direct injection chargeability. This seems to be because the charge transfer from the metal compound fine particles in the toner to the trapping agent on the surface of the photoreceptor is faster between the same elements with fewer barriers.

  However, resistance control is difficult with metal compound fine particles containing approximately 100 wt% of tin oxide.

  Therefore, in the present invention, it is more preferable to use reduction-treated tin oxide as the metal compound fine particles, which has a high direct injection charging speed, a light color, and capable of appropriate resistance control.

  It is preferable to use the metal compound fine particles after performing a correct surface treatment in order to improve the characteristics in a high temperature and high humidity environment. When the metal compound fine particles absorb moisture, problems such as (1) the effect of improving the triboelectric charging property of the toner is remarkably reduced and the image quality is deteriorated, and (2) the effect of improving the chargeability is reduced due to easy detachment from the charging member. Cheap. In that sense, a silane compound is preferable because of high water repellency as a treatment agent for the hydrophobic treatment.

  The toner used in the present invention is preferably added with inorganic fine powder having an average primary average particle size of 4 to 80 nm as a fluidizing agent and a transfer aid. Inorganic fine powder is added to improve toner fluidity, uniform triboelectric charge amount of toner particles, and improve transferability. However, the triboelectric charge amount of toner can be improved by hydrophobizing inorganic fine powder. It is also a preferable form to provide functions such as adjustment of environmental stability and improvement of environmental stability.

  When the average primary average particle diameter of the inorganic fine powder is larger than 80 nm, the image density is lowered, and it is difficult to obtain a stable and good image. Also, good toner fluidity cannot be obtained, charging to toner particles tends to be non-uniform, fog increases, and transfer residual toner increases. Further, as will be described later, since the jet property index of the toner becomes lower and the contamination of the charging member becomes remarkable in the cleanerless system, it is difficult to improve the charging property even when the metal compound fine particles according to the present invention are used. On the other hand, when the average primary average particle size of the inorganic fine powder is smaller than 4 nm, the cohesiveness of the inorganic fine powder is increased, and the particle size distribution is wide and has strong cohesiveness that is difficult to break even by crushing treatment instead of primary particles. It tends to behave as an aggregate and easily causes image defects due to development of the aggregate, damage to the image carrier or developer carrier, and the like. In order to make the triboelectric charge amount distribution of the toner particles more uniform, the average primary average particle diameter of the inorganic fine powder is more preferably 6 to 70 nm.

  In the present invention, the average primary average particle size of the inorganic fine powder is measured by a photograph of the toner magnified by a scanning electron microscope, and further by an elemental analysis means such as XMA attached to the scanning electron microscope. 100 or more primary particles of inorganic fine powder adhering to or liberating from the toner surface are measured while comparing photographs of the toner mapped with the elements contained in the body, and obtained as the number average average particle diameter. I can do it.

  As the inorganic fine powder used in the present invention, silica, alumina, titanium oxide, or a composite oxide thereof can be used.

For example, both silica, so-called fine silica powder, so-called dry process produced by vapor phase oxidation of silicon halide or dry silica called fumed silica, and so-called wet silica produced from water glass, etc. Although available, fewer silanol groups at the inside of the end surface and the silica fine and Na ₂ O, SO ₃ ^- it is preferable less dry silica of manufacturing residue such. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Is also included.

  The addition amount of the inorganic fine powder having an average primary average particle diameter of 4 to 80 nm is preferably 0.1 to 3.0% by mass with respect to the toner, and the effect is obtained when the addition amount is less than 0.1% by mass. When it exceeds 3.0% by mass, the fixing property is deteriorated.

  Here, the inorganic fine powder is preferably a hydrophobized product in view of characteristics in a high temperature and high humidity environment. When the inorganic fine powder mixed with the toner absorbs moisture, the triboelectric charge amount of the toner is remarkably reduced, and the toner is likely to scatter.

  As treatment agents for hydrophobizing treatment, treatment agents such as silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane compounds, silane coupling agents, other organic silicon compounds, and organic titanium compounds may be used alone or You may process together.

  Among these, those treated with silicone oil are preferable, and more preferably, the inorganic fine powder is treated with silicone oil at the same time or after hydrophobizing with a silane compound, and then treated with silicone oil. It is good for keeping the amount high and preventing toner scattering.

  The conditions for hydrophobizing the inorganic fine powder are as follows. For example, a silylation reaction is performed with a silane compound as a first-stage reaction to eliminate silanol groups by chemical bonding, and then a hydrophobic thin film is formed on the surface with silicone oil as a second-stage reaction.

The silicone oil preferably has a viscosity at 25 ° C. of 10 to 200,000 mm ² / s, and more preferably 3,000 to 80,000 mm ² / s. If it is less than 10 mm ² / s, the inorganic fine powder is not stable and the image quality tends to deteriorate due to heat and mechanical stress. If it exceeds 200,000 mm ² / s, uniform processing tends to be difficult.

  As the silicone oil used, for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil and the like are particularly preferable.

  As a method for treating the silicone oil, for example, the inorganic fine powder treated with the silane compound and the silicone oil may be directly mixed using a mixer such as a Henschel mixer, or the silicone oil is sprayed onto the inorganic fine powder. A method may be used.

  Alternatively, after dissolving or dispersing silicone oil in an appropriate solvent, inorganic fine powder may be added and mixed to remove the solvent. A method using a sprayer is more preferable in that the formation of inorganic fine powder aggregates is relatively small.

  The treatment amount of the silicone oil is 1 to 23 parts by mass, preferably 5 to 20 parts by mass with respect to 100 parts by mass of the inorganic fine powder. If the amount of silicone oil is too small, good hydrophobicity cannot be obtained, and if it is too large, problems such as fogging occur.

  Next, the behavior of the toner attached to the charging member will be considered.

  When the toner adheres to the contact charging member that is driven during the operation of the printer, if the toner remains attached without being removed, problems such as fusion to the charging member and scraping of the photosensitive member are caused. Since the surface of the charging member fused with the toner becomes highly resistant, even if metal compound fine particles with a large specific surface area and a large number of contact points are used, the effect of maintaining the charging property is exhibited to some extent, but only the effect Is not enough. As a more preferable situation, the adhesion force between the contaminated toner and the charging member surface is loosened due to vibration or the like when the contact charging member is driven, and the contaminated toner is excluded on the photosensitive member by an electric field due to a potential difference between the member surface and the photosensitive member. It is to be done. For this purpose, it is preferable to use a toner that smoothly transitions from a static state to a fluid state.

  There are many methods for evaluating fluidity, which is one of the characteristics of toner, but by measuring several phenomena and characteristics related to fluidity, Carr's jet can be used as an index for comprehensively evaluating powder fluidity. There is a sex index.

  The jetability index is a measure of the likelihood of the flushing phenomenon. Flushing means that a fluid whose fluidity has been lowered in a stationary state becomes a fluid state like a liquid when it starts to flow due to vibration.

  This means that the higher the jet performance index value, the higher the jet performance of the toner powder.

  In the present invention, the jetability index was measured by the following method.

  Using a powder tester P-100 (manufactured by Hosokawa Micron Corporation), parameters of repose angle, collapse angle, difference angle, degree of compression, degree of aggregation, spatula angle and degree of dispersion are measured. The values obtained for each were applied to the Carr jetability index table, converted into respective indices of 25 or less, and the sum of the indices obtained from each parameter was calculated as the fluidity index / jetability index. The measurement method of each parameter is shown below.

(1) Angle of repose 150 g of toner is passed through a mesh having a mesh opening of 710 μm, and the toner is deposited on a circular table of direct 8 cm. At this time, the toner is deposited so that the toner overflows from the end of the table. The angle of repose was determined by measuring the angle formed between the ridge line of the toner deposited on the table and the circular table surface with a laser beam.

(2) Compressibility The degree of compression can be determined from the loosely packed bulk density (loose apparent specific gravity A) and the tapping bulk density (hardened apparent specific gravity P).

Compressibility (%) = 100 (PA) / P
○ Spacious Apparent Specific Gravity Measurement Method 150 g of toner is gently poured into a cup having a diameter of 5 cm and a height of 5.2 cm and a capacity of 100 cc. When the measurement cup is filled with toner, the surface of the toner is ground, and the loose apparent specific gravity is calculated from the amount of toner filled in the cup.

  ○ Measurement method of solid apparent specific gravity Add the attached cap to the measuring cup used for loose apparent specific gravity.

  Fill the cup with toner and tap the cup 180 times. When tapping is complete, remove the cap and remove excess toner from the cup. The solid apparent specific gravity is calculated from the amount of toner filled in the cup.

  The apparent specific gravity value is inserted into the compression degree formula to obtain the compression degree.

(3) Spatula angle Place the bottom of the 10 cm x 15 cm bat so that it touches the 3 cm x 8 cm spatula. Deposit toner on the spatula. At this time, the toner is deposited so as to rise on the spatula. Then, only the bat is gently lowered, and the inclination angle of the toner side surface remaining on the spatula is measured with a laser beam.

  Then, after applying an impact once with a shocker attached to the spatula, the spatula angle is measured again.

  The average of this measured value and the measured value before giving an impact was calculated as a spatula angle.

(4) Aggregation degree A sieve is set on the vibration table in the order of openings of 250 μm, 150 μm, and 75 μm from the top. The vibration amplitude is 1 mm, the vibration time is 20 seconds, and 5 g of toner is gently put on it to vibrate. After the vibration stops, measure the weight remaining on each sieve.

(Amount of toner remaining on upper screen) ÷ 5 (g) × 100... A
(Amount of toner remaining on the middle screen) ÷ 5 (g) × 100 × 0.6... B
(Amount of toner remaining on the lower screen) ÷ 5 (g) × 100 × 0.2... C
a + b + c = calculation degree (%)

  The value obtained from the parameters is converted into an index of 25 or less according to the Carr's flowability index and jetability index table (Chemical Engineering. Jan. 18.1965), and the sum of these values becomes the Carr's fluidity index.

(1) + (2) + (3) + (4) = (Carr's liquidity index)
(5) Collapse angle After the angle of repose is measured, impact is applied three times with a shocker to the bat on which the measurement circular table is placed. Thereafter, the angle of the toner remaining on the table is assumed using a laser beam, and the collapse angle is obtained.

(6) Difference angle The difference between the angle of repose and the collapse angle is the difference angle.

(7) Dispersion 10 g of toner is dropped as a lump onto a watch glass having a diameter of 10 cm from a height of about 60 cm. Then, the toner remaining on the watch glass is measured, and the degree of dispersion is obtained by the following equation.

Dispersity (%) = ((10− (amount of toner remaining on the plate)) × 10
The sum of the index that can be converted from the values of (5), (6), and (7) and the index corresponding to the fluidity index value obtained above can be obtained as the jetability index from the aforementioned Carr table.

  When this measurement is performed, if the toner has good jet properties such that the jet property index is greater than 80, toner fusion to the charging member is unlikely to occur even in a cleanerless system including a contact charging step. The charging property maintaining effect by the metal compound fine particles according to the present invention is sufficiently exhibited.

  When the jetability index is 80 or less, if toner layers are stacked on the surface of the charging member, it is difficult to flow even if force is applied. Therefore, if the printer is used as it is, the toner is fused. It becomes difficult to maintain chargeability.

  In order to achieve the jet property index of the toner of the present invention, the jet property index is changed by changing the average particle diameter of the fluidizing agent added to the toner and the processing conditions (mixing time, etc.) of the mixing device used at the time of addition. Can be changed.

  For example, Henschel mixer (made by Mitsui Mining); Super mixer (made by Kawata); Ribocorn (made by Okawara Seisakusho); Nauta mixer, turbulizer, cyclomix (made by Hosokawa Micron) Spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.);

  The photoconductor was coated with a 5% by weight methanol solution of polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) on an aluminum cylinder having a diameter of 30 mm × 260.5 mm as a support, and 0.5 μm below. A pulling layer is provided. Next, in the following structural formula, the diffraction angle 2θ ± 0.2 ° in the X-ray diffraction spectrum of CuKα has strong peaks at 9.0, 14.2, 23.9, 27.1 °,

オキシチタニウムフタロシアニン顔料４部（質量部、以下同様）、ポリビニルブチラール樹脂ＢＸ―１（積水化学（株）製）２部、および、シクロヘキサノン８０部を、φ１ｍｍガラスビーズを用いたサンドミル装置で、４時間ほど分散した。この溶液を、前記下引き層上に塗布し、１０５℃、１０分熱風乾燥して、０．２μｍの電荷発生層を形成した。

4 parts of oxytitanium phthalocyanine pigment (parts by mass, the same applies hereinafter), 2 parts of polyvinyl butyral resin BX-1 (manufactured by Sekisui Chemical Co., Ltd.), and 80 parts of cyclohexanone for 4 hours in a sand mill using φ1 mm glass beads It was dispersed. This solution was applied onto the undercoat layer and dried with hot air at 105 ° C. for 10 minutes to form a 0.2 μm charge generation layer.

  Next, the following structural formula:

化合物１０部、及び、ビスフェノールＺ型ポリカーボネート（商品名：Ｚ―５００、三菱ガス化学（株）製）１０部を、モノクロロベンゼン１００部に溶解した。この溶液を、前記電荷発生層上に塗布し、１０５℃、１時間をかけて熱風乾燥して、２０μｍの電荷輸送層を形成した。

10 parts of the compound and 10 parts of bisphenol Z-type polycarbonate (trade name: Z-500, manufactured by Mitsubishi Gas Chemical Co., Ltd.) were dissolved in 100 parts of monochlorobenzene. This solution was applied on the charge generation layer and dried with hot air at 105 ° C. for 1 hour to form a 20 μm charge transport layer.

  Next, as a protective layer, 30 parts of antimony-doped tin oxide ultrafine particles surface-treated with a compound represented by the following structural formula (treatment amount: 7%),

エタノール：１２０部を、サンドミルにて、６６時間かけて分散を行い（平均平均粒径０．０３μｍ）、更に、ポリテトラフルオロエチレン微粒子（平均平均粒径０.１８μｍ）：３５部を加えて、さらに２時間分散を行い第１の調合液とした。更に、アルミナ微粒子（商品名：ＡＫＰ―Ｇ０１５、住友化学（株）製）を２５部、エタノール：１００部をサンドミルにて２５時間かけて分散をおこない（平均平均粒径０．０９μｍ）、第1の調合液に加えた。その後、レゾール型フェノール樹脂（商品名：ＰＬ―４８０４：群栄化学工業（株）製）を樹脂成分として３０部を溶解し、調合液とし、実施例１とした。

120 parts of ethanol was dispersed in a sand mill for 66 hours (average average particle diameter 0.03 μm), and further, polytetrafluoroethylene fine particles (average average particle diameter 0.18 μm): 35 parts were added, Further, dispersion was performed for 2 hours to obtain a first preparation liquid. Further, 25 parts of alumina fine particles (trade name: AKP-G015, manufactured by Sumitomo Chemical Co., Ltd.) and 100 parts of ethanol are dispersed in a sand mill for 25 hours (average average particle size 0.09 μm). Added to the formulation. Thereafter, 30 parts of a resol type phenolic resin (trade name: PL-4804: manufactured by Gunei Chemical Industry Co., Ltd.) was dissolved as a resin component to prepare a preparation solution.

  Using this prepared solution, a film was formed on the above charge transport layer by a dip coating method and dried in hot air at a temperature of 140 ° C. for 1.5 hours to obtain a protective layer. At this time, the film thickness of the obtained protective layer was measured using an instantaneous multi-photometry system MCPD-2000 (manufactured by Otsuka Electronics Co., Ltd.) due to light interference because of the thin film, and the film thickness was 3 μm. . Moreover, the dispersibility of the protective layer preparation liquid was good, and the film surface was a uniform surface without unevenness.

  In Example 1, 40 parts of tin oxide and 30 parts of polytetrafluoroethylene fine particles were used as the first preparation liquid. The alumina fine particles were 45 parts. Furthermore, the resin component of the protective layer was 45 parts of a resol type phenol resin (trade name: PR-53123, manufactured by Sumitomo Durez Co., Ltd.).

  In Example 1, 20 parts of tin oxide was used as the first preparation liquid and dispersed for 50 hours, and 15 parts of polytetrafluoroethylene fine particles were added, and dispersed for the same time as in Resin Example 1. Thereafter, in Example 1, 25 parts of the alumina fine particles and 70 parts of ethanol were dispersed and added to the first preparation liquid. Resin components of the protective layer were acrylic polyol resin (trade name: ACRIDIC A-801P, nonvolatile content 50%, Dainippon Ink & Chemicals, Inc.) 45 parts, and block isocyanate (trade name: Pernock DN995, nonvolatile content 75). %, Dainippon Shin Chemical Co., Ltd.) was 7 parts.

  In Example 1, the resin component of the protective layer is a thermosetting epoxy resin represented by the following structural formula (10),

更に、硬化触媒として下記構造式（１１）で示される酸無水物部を７部添加した。

Further, 7 parts of an acid anhydride part represented by the following structural formula (11) was added as a curing catalyst.

  In Example 1, 20 parts of the resin component of the protective layer was an acrylic resin having the following structural formula (neopentyl glycol-modified trimethylpropane diacrylate, trade name: Karayad R-604, manufactured by Nippon Kayaku Co., Ltd.),

更に、開始剤として下記構造式のベンゾイン（商品名：ニッソキュアーＭＢ、日本曹達）を４部、

Furthermore, 4 parts of benzoin (trade name: Nissoure MB, Nippon Soda) of the following structural formula as an initiator,

下記構造式のベンゾフェノン系エネルギー移動剤（２，２´ジクロロ−４、４´―ジヒドロキシベンゾフェノン）を４部

4 parts of benzophenone energy transfer agent (2,2'dichloro-4,4'-dihydroxybenzophenone)

を加え保護層用塗工液を設けた。次いで、先の電荷輸送層上に浸漬塗布法により、膜を形成した後、高圧水銀灯にて１６０Ｗ／ｃｍ^２の光強度で３２０ｎｍ以下の波長をカットした紫外線を３０秒間照射して光硬化を行ない、その後１００℃で１時間熱風乾燥して保護層を設けた。このとき得られた膜厚は２μｍであった。

And a protective layer coating solution was provided. Next, after forming a film on the previous charge transport layer by dip coating, photocuring is performed by irradiating with a high-pressure mercury lamp with ultraviolet light with a light intensity of 160 W / cm ² with a wavelength of 320 nm or less cut for 30 seconds. Then, it was dried with hot air at 100 ° C. for 1 hour to provide a protective layer. The film thickness obtained at this time was 2 μm.

  In Example 1, the inorganic insulating fine particles were aluminum nitride having an average particle size of 0.3 μm.

  In Example 1, the inorganic insulating fine particles were zirconium oxide having an average particle size of 0.35 μm.

  In Example 1, the inorganic insulating fine particles were silicon nitride having an average particle size of 0.5 μm.

  In Example 1, the conductive fine particles were indium oxide doped with tin having an average particle size of 0.07 μm.

  In Example 1, the conductive fine particles were tin oxide doped with tantalum having an average particle diameter of 0.01 μm.

  In Example 1, the resin component of the protective layer was Polycarbo Z (trade name: Iupilon Z-600, viscosity average molecular weight: 60,000, manufactured by Mitsubishi Gas Chemical Co., Ltd.), and the drying temperature was 120 ° C.

  In Example 11, the resin component of the protective layer was polyarylate (trade name: U-100, manufactured by Unitika Ltd.).

(Comparative Example 1)
In Example 1, the protective layer was formed except for the conductive fine particles and the inorganic insulating fine particles. The film thickness was 0.5 μm.

(Comparative Example 2)
In Example 1, a protective layer was formed by removing only the conductive fine particles. The film thickness was the same as in Comparative Example 2.

(Comparative Example 3)
In Example 3, a protective layer was formed except for the inorganic insulating fine particles.

(Comparative Example 4)
In Example 3, the dispersion was carried out with 150 parts of conductive fine particles and 300 parts of ethanol to prepare a first preparation liquid. Other than that was the same as Example 1.

(Comparative Example 5)
In Example 3, 4 parts of conductive fine particles were used.

(Comparative Example 6)
In Example 3, 100 parts of inorganic insulating fine particles were used.

  The average particle size of the polytetrafluoroethylene particles and the inorganic insulating fine particles used in the above examples and comparative examples is the median by using an ultracentrifugal automatic particle size analyzer / recorder (trade name: CAPA-700, manufactured by Horiba). The diameter was measured.

  The median diameter of the conductive fine particles used in the above Examples and Comparative Examples was measured with a dynamic light scattering photometer (trade name: DLS7000, manufactured by Otsuka Electronics Co., Ltd.).

  Hereinafter, the PV value of the waviness surface, the PV value of the roughness surface, and the abundance ratio G are shown.

  The surface shape was measured in the WAVE mode over a range of about 32 × about 32 μm with a × 50 objective lens using a micromap (manufactured by Ryoka System). Next, the data was set using a software called Wave 2 and the cut-off value λc was set to 0.003 mm, whereby the surface shape was separated into a wavy surface and a rough surface, and a PV value was obtained.

  Further, the photosensitive layer is peeled off from the conductive support, a cross section of the photosensitive layer is prepared by a microtome, and elemental analysis of the conductive particles and inorganic fine particles is performed with a transmission electron microscope (JEM3010, manufactured by JEOL Ltd.). And the ratio was obtained by the FP method. The results are shown below.

次に、モノクロレーザープリンタ（商品名：ＨＰ ＬａｓｅｒＪｅｔ４１００、ヒューレットパッカード社（製））で１万枚通紙した結果を示す。通紙環境は、ＮＮ（２３℃、５５％）で行なった。削れ量は２３℃、５５％ＲＨの環境下で通紙前後の感光体の膜厚差を測定した量である。

Next, the result of passing 10,000 sheets with a monochrome laser printer (trade name: HP LaserJet 4100, manufactured by Hewlett-Packard Company) is shown. The paper passing environment was NN (23 ° C., 55%). The amount of scraping is an amount obtained by measuring the difference in film thickness of the photoreceptor before and after passing through the paper at 23 ° C. and 55% RH.

次に、下記に示す、注入帯電装置で1万枚通紙した結果を示す。

Next, the result of passing 10,000 sheets by the injection charging device shown below is shown.

[Toner Production Example 1]
Material Composition / Binder Resin (Styrene-acrylic resin (glass transition temperature Tg by DSC 58 ° C., acid value 23.0 mg KOH / g, MPC by GPC (number average molecular weight) 7000, Mw (weight average molecular weight) 400000, monomer) Ratio: 72.5 parts of styrene, 20 parts of n-butyl acrylate, 7 parts of mono-n-butyl malate, 0.5 part of divinylbenzene) 100 parts by mass, magnetic iron oxide (average average particle size: 0.20 μm, BET specific surface area) : 8.0 m ² / g, coercive force: 3.7 kA / m, saturation magnetization: 82.3 Am ² / kg, remanent magnetization: 4.0 Am ² / kg 95 parts by mass, polypropylene wax (melting point 143 ° C., 25 ° C. 4 parts by mass / charge control agent (iron complex of azo compound) 2 parts by mass Biaxial extruder heated to 130 ° C. The kneaded material was melt-kneaded and then cooled by a hammer mill, and mechanically pulverized using a turbo mill (manufactured by Turbo Kogyo Co., Ltd.). By using a classifier (elbow jet classifier manufactured by Nittetsu Mining Co., Ltd.), ultrafine powder and coarse powder were strictly classified and removed to obtain black powder 1. The resulting black powder 1 had a weight average diameter of 7.8 μm. there were.

Next, 100 parts by weight of the above black powder 1 Hydrophobic silica having a primary average particle size of 8 nm (BET 100 m ² / g hydrophobized with dimethyl silicone oil and hexamethyldisilazane) 1.0 part by weight 0.4 parts by mass of metal compound fine particles 1 The above materials were mixed for 180 seconds with a Henschel mixer FM10C / l (manufactured by Mitsui Mining Co., Ltd.) to obtain toner 1. The obtained toner 1 had a jetability index of 90.

[Production Example 1 of Charging Member]
A SUS roller having a diameter of 6 mm and a length of 264 mm is used as a core, and a medium-resistance foamed urethane layer is formed on the core as a roller. The medium resistance foam urethane layer is formulated with urethane resin, carbon black as a conductive material, sulfiding agent, foaming agent, etc. Further, the shape and surface properties were adjusted by cutting and polishing to prepare a charging member 1 having a diameter of 12 mm and a length of 234 mm as a flexible member.

The obtained charging member 1 had a resistance value of 10 ⁵ Ωcm and a hardness of 30 degrees in Asker C hardness.

  FIG. 6 shows an overall schematic configuration of the image forming apparatus of this example. FIG. 6 shows a laser printer (recording apparatus) of a simultaneous development cleaning process (cleanerless system) using a transfer type electrophotographic process. It has a process cartridge from which a cleaning means such as a cleaning blade is removed, uses toner 1 as toner, and is arranged so that the toner layer on the toner carrier and the image carrier are not in contact with each other. Contact development is used.

  The photosensitive member 61 as an image carrier is a rotary drum type OPC photosensitive member, and is driven to rotate at a peripheral speed (process speed) of 94 mm / sec in the X direction of an arrow.

As the contact charging member, the charging member 1 obtained in the charging member manufacturing example 1 is used as the charging roller 62. As shown in the figure, the charging roller 62 has a predetermined resistance against the photoreceptor 61 against elasticity. It is disposed in pressure contact with the pressing force. Reference numeral n denotes a charging contact portion that is a contact portion between the photosensitive member 61 and the charging roller 62. In this example, the charging roller 22 is rotationally driven at a peripheral speed of 100% in the facing direction (arrow Y direction) at the charging contact portion n that is a contact surface with the photoreceptor 61. The surface of the charging roller 62 has a relative speed difference of 200% relative to the surface of the photoreceptor 61. The metal compound fine particles 1 are coated on the surface of the charging roller 62 so that the coating amount is uniform at approximately 1 × 10 ⁴ particles / mm ² .

  Further, a DC voltage of −650 V was applied as a charging bias to the metal core 62a of the charging roller 62 from a charging bias application power source. In this example, the surface of the photosensitive member 61 is uniformly charged by a direct injection charging method at a potential (−630 V) substantially equal to the voltage applied to the charging roller 62.

  A laser beam scanner (exposure device) 63 including a laser diode, a polygon mirror, etc., which is an exposure means, outputs a laser beam whose intensity is modulated in accordance with a time-series electric digital pixel signal of the target image information. Then, the uniformly charged surface of the photoreceptor 61 is scanned and exposed. By this scanning exposure, an electrostatic latent image corresponding to the target image information is formed on the surface of the rotating photoreceptor 61. The electrostatic latent image on the surface of the photoreceptor 61 is developed as a toner image by a developing device 64 as a developing unit.

  The developing device 64 of this example is a non-contact type reversal developing device using the toner 1 as the toner.

As a toner carrier, a developing sleeve 264a having a resin layer having a layer thickness of about 7 μm and a JIS centerline average roughness (Ra) of 1.0 μm formed on an aluminum cylinder having a diameter of 16 mm blasted on the surface is used. In addition, a magnetic roll of 90 mT (900 gauss) of developing magnetic pole is included, and an elastic blade 64c made of urethane having a thickness of 1.0 mm and a free length of 1.5 mm as a toner layer thickness regulating member is 29.4 N / m (30 g / cm). The contact was made with linear pressure. The gap between the photoreceptor 61 and the developing sleeve 64a was 290 μm.
・ Phenolic resin 100 parts ・ Graphite (volume average average particle size of about 7 μm) 90 parts ・ Carbon black 10 parts In addition, the developing sleeve 64a is exposed to the developing part a (developing area part) which is a part facing the photoreceptor 61. The photoconductor 61 is rotated at a peripheral speed of 120% of the peripheral speed of the photoconductor 61 in the rotation direction and the forward direction (arrow W direction).

The developing sleeve 64a is coated with a thin layer of toner by an elastic blade 64c. The layer thickness of the toner with respect to the developing sleeve 64a is regulated by the elastic blade 64c, and an electric charge is applied. At this time, the amount of toner coated on the developing sleeve 64a was 16 g / m ² .

The toner coated on the developing sleeve 64a is conveyed to the developing portion a, which is a facing portion between the photosensitive member 61 and the developing sleeve 64a, by the rotation of the developing sleeve 64a. A developing bias voltage is applied to the sleeve 64a from a developing bias applying power source. The development bias voltage is a superposition of a DC voltage of −440 V and a rectangular AC voltage having a frequency of 1600 Hz and a peak-to-peak voltage of 1500 V (electric field strength of 5 × 10 ⁶ V / m). In the meantime, one-component jumping development was performed in the developing section a.

  A medium-resistance transfer roller 65 as a contact transfer unit is brought into contact with the photoreceptor 61 with a linear pressure of 98 N / m (100 g / cm) to form a transfer contact portion b. The transfer material P is fed to the transfer contact portion b from a paper feed unit (not shown) at a predetermined timing, and a predetermined transfer bias voltage is applied to the transfer roller 65 from a transfer bias application power source. The toner image on the 61 side is sequentially transferred onto the surface of the transfer material P fed to the transfer contact portion b.

In this example, the transfer roller 65 has a volume resistance value of 5 × 10 ⁸ Ωcm, and transfer was performed by applying a DC voltage of + 2000V. That is, the transfer material P introduced into the transfer contact portion b is nipped and conveyed by the transfer contact portion b, and the toner images formed and supported on the surface of the photoreceptor 61 on the surface side are successively subjected to electrostatic force. It is transferred by pressing force. The transfer material P, which is fed to the transfer contact portion b and receives the transfer of the toner image on the photoconductor 61 side, is separated from the surface of the photoconductor, and is introduced into a fixing device 66 such as a heat fixing system as fixing means. The toner image is fixed and discharged as an image formed product (print, copy) to the outside of the apparatus.

  In the image forming apparatus of this example, the cleaning unit is removed, and residual toner remaining on the surface of the photoconductor 61 after the transfer of the toner image to the transfer material P is not removed by the cleaner, and the photoconductor 61 is rotated. At the same time, it reaches the developing portion a via the charging contact portion n and is simultaneously cleaned (collected) by the developing device 64.

  Conventionally, since the toner is an insulator, the mixing of the untransferred toner into the charging contact portion n is a factor that causes a charging failure in charging the photosensitive member. However, even in this case, since the metal compound fine particles 1 having a large BET value are present in the charging contact portion n between the photosensitive member 61 and the charging roller 62, the contact property and the contact resistance of the charging roller 62 to the photosensitive member 61 are high. Therefore, regardless of the contamination of the charging roller 62 due to the transfer residual toner, ozone-less direct charging can be stably maintained over a long period of time with a low applied voltage, and uniform chargeability can be provided.

In this embodiment, 100 g of the toner 1 is filled in the image forming apparatus and used until the toner amount is reduced in the toner cartridge by the image pattern including only the horizontal line having the printing area ratio of 2%. As a transfer material, A4 copy paper of 75 g / m ² was used.

It is a figure which shows the example of the layer structure of the electrophotographic photoreceptor of this invention. 1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member of the present invention. It is a figure which shows the example of the schematic of the electrophotographic apparatus of the injection charge of this invention. It is a figure which shows the example of the schematic of the electrophotographic apparatus of the injection charge of this invention. It is a figure which shows the example of the schematic of the electrophotographic apparatus of the injection charge of this invention. It is a figure which shows the schematic of the electrophotographic apparatus used for the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Protective layer 2 Charge transport layer 3 Charge generation layer 4 Conductive support 5 Binder layer 6 Undercoat layer 11 Electrophotographic photoreceptor 12 Axis 13 Charging means 14 Exposure light 15 Developing means 16 Transfer means 17 Transfer material 18 Fixing means 19 Cleaning means 20 Pre-exposure light 21 Process cartridge 22 Guide means

Claims (14)

  In an electrophotographic photosensitive member comprising at least a conductive support, a photosensitive layer, and a protective layer, the surface shape of the protective layer is separated into a wavy surface and a rough surface with a cutoff value λc: 0.003 mm. The PV value A of the surface is 0. 1 to 1.5 μm, the PV value B of the roughness surface is 0.001 to 0.8 μm, and A> B. An electrophotographic photoreceptor.   The protective layer includes at least a binder resin, conductive fine particles and fine particles having an inorganic insulating property, and the average particle size of the inorganic fine particles is 0.02 to 2 μm. 2. The electrophotographic photosensitive member according to 1. 3. The electrophotographic photosensitive member according to claim 1, wherein the abundance ratio G of the number of conductive particles E and the number of inorganic fine particles F contained in the protective layer is 4 ≦ E / F ≦ 10 ⁵ .   4. The electrophotographic photosensitive member according to claim 1, wherein the conductive fine particles and the inorganic fine particles contained in the protective layer are 10% or more and 70% or less with respect to the total weight ratio of the protective layer.   5. The electrophotographic photoreceptor according to claim 1, wherein the curable resin is at least one selected from the group consisting of a phenol resin, an acrylic resin, an epoxy resin, a siloxane resin, and a urethane resin.   The electrophotographic photosensitive member according to claim 1, wherein the protective layer has a lubricant.   The electrophotographic photosensitive member according to claim 1, wherein the lubricant includes fluorine, organic fine particles containing silicon, or silicone oil. The electrophotographic apparatus using the electrophotographic photosensitive member according to claim 1, wherein the electrophotographic apparatus has charged particles mainly composed of conductive particles having an average particle diameter of 10 μm to 10 nm, and conductivity and elasticity. A charged particle carrier that carries the charged particles and has a surface having the surface, and the charged particles come into contact with the member to be charged, and the particles carried on the carrier in the charging device that charges the surface of the member to be charged An electrophotographic apparatus comprising a charging device having a resistance of 10 ¹² to 10 ⁻¹ Ω / cm and a loading amount of the particles of 0.1 mg / cm ² to 50 mg / cm ^2. .   9. The electrophotographic apparatus according to claim 8, wherein 1 ≧ Rc ≧ 0.2 when the ratio of the conductive particles covering the charged particle carrier is defined as a coverage ratio Rc. The charged particle bearing member surface roughness Ra of 1 to 500 [mu] m, electrophotographic apparatus according to claim 1 and 2, wherein the surface resistivity is ^{10 -4} ~10- 10 Ω.   4. The charging device according to claim 1, wherein the charged particle carrier is an elastic body having a porous surface. A toner having at least toner particles and non-magnetic metal compound fine particles, wherein the toner particles are formed of at least a binder resin and a colorant, and the toner has a mass average average particle size of 3 μm or more and 12 μm or less; The metal compound fine particles have a specific surface area of 5 × 10 ⁵ (cm ² / cm ³ ) or more and 100 × 10 ⁵ or less, a volume-based median diameter (D50) of 0.4 μm or more and 4.0 μm or less, and a toner mass average. The electrophotographic apparatus according to any one of claims 8 to 11, wherein the electrophotographic photosensitive member according to any one of claims 1 to 7 is used, wherein the toner is conductive fine particles having an average particle size less than the average particle diameter. 13. The electrophotographic apparatus according to claim 8, wherein the toner according to claim 12 is used, wherein the metal compound fine particles have a volume resistance of 1 × 10 ⁻¹ to 1 × 10 ⁹ Ωcm or less.   An electrophotographic photosensitive member according to any one of claims 1 to 13, a charging means for charging the electrophotographic photosensitive member, an exposure means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image, Integrally supporting with at least one means from the group consisting of developing means for developing the toner on the electrophotographic photosensitive member on which the latent image is formed, and transferring means for transferring the toner image on the electrophotographic photosensitive member onto the transfer material; A process cartridge which is detachable from an electrophotographic apparatus main body.

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