JP2018155877A - Cleaning blade, image forming apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that can reduce slip-through of toner in image formation of an electrophotographic system even when images with a low printing ratio are continuously output.SOLUTION: In a cleaning blade 201 of an image forming apparatus of an electrophotographic system, a DLC film 220 is arranged at a portion on the upstream side in the direction of rotation of an image carrier 10 with respect to at least an edge part 212 of a plate-like member 210 having elasticity. A position of an end edge of the DLC film 220 on the upstream side of the edge part 212 is a position 10 to 100 μm away from the edge part 212. In blade cleaning, the end edge is located in a stationary layer 500 formed between a surface of an image carrier 10 and the cleaning blade 201.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a cleaning blade, and an image forming apparatus and an image forming method having the same.

  An electrophotographic image forming apparatus generally has a cleaning device that removes toner particles remaining on an image carrier. As a cleaning method, an elastic plate-like member is brought into contact with the image carrier, and the plate-like member is brought into contact with a contact portion (hereinafter also referred to as “cleaning nip portion”) between the plate-like member and the image carrier. Thus, a blade cleaning method is widely employed in which the toner particles on the image carrier are scraped by rubbing the surface of the image carrier.

  In the cleaning method, an edge portion of the plate-like member, for example, a side edge in the longitudinal direction of the rectangular parallelepiped plate-like member is brought into contact with the surface of the image carrier, and the plate-like member contacts the surface of the image carrier. By reducing the area, the contact pressure of the plate-like member in the cleaning nip is kept high, and toner particles are prevented from passing through the cleaning nip.

  Further, on the upstream side of the cleaning nip portion in the moving direction of the surface of the image carrier, toner particles, external additives detached from the toner particles, toner base particles after the external additive is detached from the toner particles, etc. Is blocked to form a powder layer called a stationary layer. The stationary layer attenuates the rush energy of the toner particles into the nip portion, and thus contributes to preventing the toner particles from passing through the nip portion.

  Polyurethane rubber is widely used as the material for the plate member. However, the plate-like member made of polyurethane rubber has a problem that the edge portion is worn by rubbing with the image carrier after long-term use. When the edge portion wears, the contact area between the plate member and the image carrier increases, and the contact pressure of the plate member at the cleaning nip portion decreases. For this reason, there may be a case where a cleaning defect called toner slip occurs due to the toner particles passing through the cleaning nip portion.

  On the other hand, a diamond-like carbon film (hereinafter also referred to as “DLC film”) is known as a technique for improving the wear resistance of the plate-like member (see, for example, Patent Document 1). The DLC film has a higher hardness and a lower frictional resistance than the material of the plate-like member (polyurethane rubber). For this reason, in the cleaning blade having the DLC film, wear at the cleaning nip portion is drastically reduced. Therefore, in electrophotographic image formation using a cleaning blade having a DLC film for the blade cleaning method, the contact pressure at the cleaning nip portion is kept high even in long-term use, and as a result, the cleaning performance is improved. .

JP 2006-090974 A

  However, if a cleaning blade having a DLC film is used for blade cleaning in electrophotographic image formation, defective cleaning may occur when the formation of the static layer is insufficient. This is presumed to be due to the following mechanism.

  The friction resistance on the surface of the DLC film is lower than the friction resistance on the surface of the plate-like member. Accordingly, the friction force against the toner particles in the static layer is also smaller on the surface of the DLC film than on the surface of the plate-like member. For this reason, when the toner particles in the stationary layer come into contact with only the surface of the DLC film with respect to the cleaning blade, the convection of the toner particles becomes gentle, and the external additive is not easily detached from the toner particles in the stationary layer. Become.

  Generally, the static layer is formed by filling a small area in the vicinity of the nip where toner particles cannot enter with a small particle size external additive, thereby blocking toner particles and toner base particles, which are larger particles. It is formed. However, when there is little detachment of the external additive from the toner particles, the particle density in the vicinity of the cleaning nip portion remains low, and the stationary layer may not be sufficiently developed. In particular, when a large amount of images with a low printing rate are continuously printed, since the toner particles directed toward the cleaning nip are few, the above-described lack of development of the stationary layer becomes more conspicuous. For this reason, a cleaning failure due to toner slipping may occur.

  An object of the present invention is to provide a technique capable of suppressing toner slipping even when an image with a low printing rate is continuously output in electrophotographic image formation.

  As a first means for solving the above problems, the present invention has a plate-like member having elasticity and including an edge portion, and a DLC film disposed on the surface of the plate-like member including the edge portion. In a cleaning blade for removing deposits from the surface of the image carrier by contacting the surface of the image carrier through the DLC film at least at the edge portion, the DLC film is at least from the edge portion. The first portion is positioned upstream of the edge portion in the moving direction of the surface of the image carrier when the cleaning blade comes into contact with the surface of the image carrier. A cleaning blade, wherein the position of the edge of the DLC film on the first portion is 10 to 100 μm from the edge portion.

  According to the present invention, as a second means for solving the above-described problem, an image carrier for carrying and transferring a toner image, and a surface of the image carrier after the toner image is transferred are brought into contact with the surface. An electrophotographic image forming apparatus having the cleaning blade for removing toner particles remaining on the surface from the surface.

  Further, according to the present invention, as a third means for solving the above-described problems, the toner particles remaining on the surface of the image carrier after the toner image carried thereon is transferred by the cleaning blade that contacts the surface. An electrophotographic image forming method in which an edge of the DLC film is located in a static layer formed between the surface of the image carrier and the first portion, including a cleaning step of removing from the surface; I will provide a.

  According to the present invention, even when an image with a low printing rate is continuously output in electrophotographic image formation, it is possible to prevent toner from slipping through.

1 is a diagram schematically illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows typically the structure of the cleaning blade of one embodiment of this invention. It is a figure which shows typically the state of the said cleaning blade in contact with the surface of an image carrier. It is a figure which expands and shows typically the contact part with the surface of the image carrier in the said cleaning blade. FIG. 5A is a diagram schematically illustrating one process of manufacturing the DLC film, and FIG. 5B is a diagram schematically illustrating an enlarged main part of the state of the one process. It is a figure which shows typically the image formed by evaluation of an Example. It is a figure for demonstrating the wear width in evaluation of an Example. It is a figure for demonstrating the plastic deformation width | variety in evaluation of an Example.

  Embodiments of the present invention will be described below. The cleaning blade in the embodiment of the present invention has a plate-like member having elasticity and including an edge portion, and a DLC film disposed on the surface of the plate-like member including the edge portion.

  As the plate-like member, a known member used for a cleaning blade in an electrophotographic image forming apparatus can be used. The plate-like member may be, for example, a rectangular parallelepiped rubber plate having a length in the axial direction of the surface of the image carrier, and the edge portion may be one side edge in the longitudinal direction.

  The material of the plate member is preferably rubber. In blade cleaning, it is preferable that the plate-like member has flexibility to follow the unevenness of the surface of the image carrier at the cleaning nip portion, and has an appropriate strength to reduce abrasion due to abrasion. It is preferable to have. Since the material of the plate member is rubber, the plate member can achieve both flexibility and strength.

  For example, the hardness of the plate-like member is preferably 60 to 80 degrees, more preferably 65 to 75 degrees as a JIS-A hardness. If the hardness is too low, the amount of deformation of the plate-like member increases, and the plate-like member itself is easily broken, the DLC film is peeled off, and the plate-like member is easily worn. If the hardness is too high, the flexibility of the plate-like member is lowered, and the followability to the image carrier may be insufficient.

  Moreover, the impact resilience of the plate-like member is preferably 20 to 80%, more preferably 30 to 75%, as a resilience coefficient measured at 25 ° C. If the rebound resilience is too low, plastic deformation of the plate-shaped member is likely to occur, and the nip width increases and the cleaning performance may deteriorate. If the rebound resilience is too high, the tip of the cleaning blade tends to vibrate, and it may be difficult to form a stationary layer, which may reduce the cleaning performance.

  The hardness and impact resilience can be adjusted by the type of material of the plate-like member, the addition ratio thereof, and the like.

  The material of the plate member is preferably polyurethane rubber from the viewpoint of the dimensional accuracy of the edge portion and its strength.

  The polyurethane rubber plate-like member can be produced by a known technique. For example, the plate-like member is prepared by preparing a polyurethane prepolymer using a polyol compound and a polyisocyanate compound, adding a curing agent and, if necessary, a curing catalyst to the polyurethane prepolymer, The polyurethane prepolymer is crosslinked, post-crosslinked in a furnace, molded into a sheet by centrifugal molding, the resulting sheet is left standing at room temperature and aged, and is cut into a flat plate with a predetermined size Manufactured.

  The polyol compound may be one kind or more, and can be appropriately selected according to the purpose. Examples thereof include a high molecular weight polyol and a low molecular weight polyol.

  Examples of the high molecular weight polyol include polyester polyol which is a condensate of alkylene glycol and aliphatic dibasic acid such as adipic acid, polycaprolactone-based polyol such as polycaprolactone ester polyol obtained by ring-opening polymerization of caprolactone, And polyether polyols such as poly (oxytetramethylene) glycol and poly (oxypropylene) glycol. Examples of the alkylene glycol include ethylene adipate ester polyol, butylene adipate ester polyol, hexylene adipate ester polyol, ethylene propylene adipate ester polyol, ethylene butylene adipate ester polyol, and ethylene neopentylene adipate ester polyol.

  Examples of the low molecular weight polyol include 1,4-butanediol, ethylene glycol, neopentyl glycol, hydroquinone-bis (2-hydroxyethyl) ether, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 4 , 4′-diaminodiphenylmethane and the like, and 1,1,1-trimethylolpropane, glycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, trimethylolethane, 1, Trivalent or higher polyhydric alcohols such as 1,1-tris (hydroxyethoxymethyl) propane, diglycerin, pentaerythritol are included.

  The polyisocyanate compound may be one or more and can be appropriately selected according to the purpose. Examples thereof include methylene diphenyl diisocyanate (MDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), Naphthylene-1,5-diisocyanate (NDI), tetramethylxylene diisocyanate (TMXDI), isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate (H6XDI), dicyclohexylmethane diisocyanate (H12MDI), hexamethylene diisocyanate (HDI), dimer acid Diisocyanate (DDI), norbornene diisocyanate (NBDI) and trimethylhexamethylene diisocyanate (TMDI) are included.

  The above-mentioned curing catalyst may be one kind or more and can be appropriately selected according to the purpose. Examples thereof include 2-methylimidazole and 1,2-dimethylimidazole. Content of the said curing catalyst can be suitably selected according to the objective, It is preferable that it is 0.01-0.5 mass%, and it is more preferable that it is 0.05-0.3 mass%.

  The edge portion is a portion that protrudes outward in the cross-sectional shape of the plate-like member, and is a portion that is brought into contact with the surface of the image carrier. The edge portion only needs to have a length that sufficiently contacts the entire length of the surface in the axial direction of the image carrier. For example, an edge (one side edge) in a cross-sectional shape that crosses the longitudinal direction of the plate-like member ).

  The DLC film is a thin film made of a carbon-based material having both carbon-carbon bonds of both diamond and graphite (graphite). The DLC film is positioned at least upstream from the edge portion in the moving direction of the surface of the image carrier with respect to the blade edge portion when the cleaning blade comes into contact with the surface of the image carrier. 1 is arranged.

  The position of the edge of the DLC film on the first portion is 10 to 100 μm from the edge portion. If the position of the edge from the edge portion is more than 100 μm, most of the particles in the stationary layer at the time of blade cleaning of the image carrier come into contact with the DLC film having a low frictional force. Contamination of the toner particles is difficult to occur, and the external additive may be insufficiently detached from the toner particles.

  If the position of the edge from the edge portion is closer than 10 μm, the cleaning blade may be suddenly drawn into the cleaning nip portion due to foreign object biting during blade cleaning of the image carrier, Due to slight wear of the DLC film, parts other than the DLC film may come into contact with the image carrier. As a result, the DLC film peels off from the edge, and the cleaning blade wears rapidly. May progress.

  The position of the edge of the DLC film on the first part is 50 μm or less from the edge part, and the particles in the stationary layer are also brought into contact with the part of the plate-like member other than the DLC film. This is preferable from the viewpoint of enhancing the effect of improving the cleaning property.

The position of the edge of the DLC film on the first part is more preferably 40 μm or less from the edge part. The DLC film is easily plastically deformed. For this reason, the cleaning nip portion of the cleaning blade is not restored as it is drawn in the moving direction of the surface of the image carrier, and the nip width of the cleaning nip portion increases with use due to such plastic deformation. There is a case to go. It is more preferable that the position of the edge is 40 μm or less because the restoring force due to the elasticity of the plate-like member becomes dominant and the plastic deformation is less likely to occur, and the nip pressure is further increased.

  More preferably, the position of the edge of the DLC film on the first portion is a position of 25 μm or less from the edge portion. The fact that the position of the edge is 25 μm or less from the edge portion further increases the probability that the toner particles in the stationary layer will come into contact with the portion of the plate member having a higher frictional force than the DLC film. More sufficient convection of the toner particles in the layer is generated, and the external additive is more easily separated from the toner particles.

  On the other hand, the position of the edge of the DLC film on the first portion is 15 μm or more from the edge portion, thereby preventing the cleaning blade from lifting from the surface of the image carrier during blade cleaning. It is preferable from the viewpoint. When the edge is at the above-mentioned position, when the particles existing in the cleaning nip portion and the stationary layer in the immediate vicinity thereof come into contact with the cleaning blade, the probability of coming into contact with the DLC film having lower friction is sufficiently increased. For this reason, the convection of particles in the cleaning nip portion and the stationary layer in the vicinity thereof is moderately suppressed, and the effect that the cleaning blade is lifted from the cleaning nip portion is sufficiently suppressed.

  Further, the thickness of the DLC film is preferably 1 μm or more from the viewpoint of suppressing wear of the DLC film accompanying long-term use and accompanying peeling of the DLC film.

  Even when the DLC film is relatively thick, the cleaning blade can be used for blade cleaning without any problem. The thickness of the DLC film is more preferably 4 μm or less from the viewpoint of suppressing deterioration in cleaning properties due to an increase in the contact area of the cleaning nip due to plastic deformation accompanying long-term use in the cleaning nip. The thickness of the DLC film can be adjusted by, for example, a film formation time when a DLC film described later is formed.

  The DLC film may be further disposed in a portion other than the first portion in the plate member. For example, the DLC film may be further disposed in the second portion. The said 2nd part is a part located in the downstream in the movement direction of the surface of the said image carrier rather than the said edge part in the said plate-shaped member. For example, from the viewpoint of suppressing wear of the cleaning blade, the position of the downstream edge of the DLC film is preferably 10 μm or more downstream from the edge portion.

  The portion of the DLC film on the downstream side of the edge portion does not affect the state of the stationary layer and contributes little to the cleaning performance. For this reason, even if the position of the edge on the downstream side is far from the edge portion, there is no particular problem, but from the viewpoint of suppressing the occurrence of plastic deformation of the cleaning blade, the position of the edge on the downstream side of the DLC film. Is preferably at a position of 5.0 mm or less downstream from the edge part, more preferably at a position of 0.5 mm or less.

  The DLC film can be produced by a known method. For example, examples of DLC film deposition methods include PVD (physical vapor deposition), which uses solid carbon as a raw material and deposits a thin film by a physical method, and hydrocarbon gas as a raw material. It includes a CVD method (chemical vapor deposition) in which a thin film is deposited by reaction.

  Examples of the PVD method include a sputtering method such as a UBMS method, an arc ion plating method such as an FCVA method, and an ionized vapor deposition method. Examples of the CVD method include a plasma CVD method in which a raw material gas is turned into plasma and generated plasma ions are deposited by applying a voltage to a substrate. The DLC film is formed by a plasma CVD method from the viewpoint of film formation at a temperature lower than the heat-resistant temperature of the rubber plate member, from the viewpoint of uniformity of film thickness, and from the viewpoint of adhesion to a rubber material. Preferably there is.

  The method for forming the DLC film is preferably a method known as a high-frequency, high-voltage pulse superposition type as disclosed in Japanese Patent Application Laid-Open No. 2001-026887, among plasma CVD methods.

  In general, the plasma CVD method includes a step of converting a hydrocarbon gas into a plasma and a step of attracting and depositing generated plasma ions on a sample, and these two steps are separated by using separate electrodes. Done in

  On the other hand, the above-described high-frequency, high-voltage pulse superposition method is characterized in that a voltage for plasma generation is directly applied to a sample (plate member), and the sample itself also has an electrode for plasma generation. . As a result, plasma with a higher density can be generated in the vicinity of the sample, so that a more uniform film can be generated even in film formation on the edge portion where the film thickness tends to be non-uniform.

  A specific film forming method is shown below. A plasma generating high frequency power source and a high voltage pulse generating power source are connected to a plate-like member in the chamber through a common feedthrough, and a film forming gas is introduced into the chamber. A high frequency pulse (pulse RF voltage) is applied to the plate member from the plasma generating high frequency power source to generate plasma around the outer shape of the plate member. Then, a negative high voltage pulse (DC pulse voltage) is applied to the plate member from the high voltage pulse generating power source in the plasma or afterglow plasma at least once, and plasma ions are applied to the surface of the plate member. Attract and attach to the part. By repeatedly applying these high-frequency pulses and negative high-voltage pulses, a DLC film is deposited on the desired portion. As the film forming gas, toluene gas or acetylene gas is preferably used.

  In the high frequency, high voltage pulse superposition type method, in order to improve the adhesion between the DLC film and the plate member, as a pretreatment step of film formation, a step of cleaning the surface of the plate member, and a plate It is preferable to introduce a step of forming an adhesive layer for the DLC film on the surface of the member.

  The step of cleaning the surface is a step of removing surface contamination by plasma ion implantation, and argon gas or hydrogen gas is preferably used as the raw material gas.

  The step of forming the adhesive layer is a step of improving the affinity between the plate-like member and the DLC film by injecting hydrocarbon plasma ions into the plate-like member, and the raw material gas is hydrogen gas or methane gas. Are preferably used.

  The voltage value of the high voltage pulse in the high frequency, high voltage pulse superposition type method is preferably large in the pretreatment process and small in the film forming process. This is because when the voltage value is small, film growth due to deposition of plasma ions becomes more dominant, and when the voltage value is large, ion implantation into the plate member becomes more dominant.

  In the case where a DLC film is formed on an edge portion such as a side edge of a rubber plate-like member, since a rubber member is generally an insulator and does not serve as a plasma generation source, a conductive support substrate, etc. A rubber material is attached to and a film is formed.

  Moreover, the range in which the DLC film is produced can be controlled by covering the periphery of the edge portion of the plate-like member and changing the covered range. Examples of the covering method include a method of sticking a tape to a portion to be covered, and a method of closely attaching a mold to a portion other than the vicinity of the edge portion of the plate-like member.

  The cleaning blade may further have other configurations than the plate-like member and the DLC film described above as long as the effects of the present embodiment can be obtained. Examples of the other configurations include a structure for specifying the mounting position of the cleaning blade with respect to the image carrier. Examples thereof include a mark indicating a contact direction of the cleaning blade with respect to the image carrier, and a specification with respect to the image carrier. And a structure for attaching the support member to the cleaning blade, such as a through hole.

  The cleaning blade can be used as a member for removing deposits from the surface of the image carrier by contacting the surface of the image carrier through the DLC film at least at the edge portion. In other words, the cleaning blade can be used as a cleaning blade in a blade cleaning method in electrophotographic image formation. The electrophotographic image formation includes an image carrier for carrying and transferring a toner image, and toner particles remaining on the surface in contact with the surface of the image carrier after the toner image is transferred. It can be performed by a known electrophotographic image forming apparatus having a cleaning blade for removal from the surface.

  The cleaning blade is brought into contact with the image carrier at the edge so that the first portion is located upstream in the moving direction of the surface of the image carrier, so that a known electrophotographic image forming apparatus is used. Used as a cleaning blade. The electrophotographic image forming method using the cleaning blade can be performed by using the cleaning blade of this embodiment in the above-described known electrophotographic image forming apparatus.

  In the image forming method, known toner particles having an external additive can be used as a developer. The developer may be a one-component developer substantially composed only of toner particles, or may be a two-component developer having toner particles and carrier particles.

  The toner particles include, for example, toner base particles containing a binder resin and a colorant, and external additives attached to the surface of the toner base particles. The toner base particles can be appropriately configured based on a known technique in accordance with an image to be formed in the image forming method.

  The external additive is a particle exhibiting an action of improving the properties of toner particles such as fluidity and charging properties, and can be appropriately selected from known ones. One or more external additives may be used, and examples thereof include inorganic fine particles, organic fine particles, and a lubricant.

  Examples of the inorganic fine particles preferably include fine particles of silica, titania, alumina, or strontium titanate. The surface of the inorganic fine particles may be subjected to a hydrophobic treatment as necessary.

  Examples of the silica fine particles include commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., and commercially available products TS- manufactured by Cabot Corporation. 720, TS-530, TS-610, H-5, MS-5.

  Examples of the titania fine particles include commercial products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products MT-100S, MT-100B, MT-500BS, MT-600, and MT-600SS manufactured by Teika Co., Ltd. , JA-1, commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Industry Co., Ltd., and commercial products IT-S, IT- manufactured by Idemitsu Kosan Co., Ltd. OA, IT-OB, IT-OC are included.

  Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd. and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

  Examples of the organic fine particles include organic fine particles having a number average primary particle size of about 10 to 2000 nm. Examples of the organic fine particle material preferably include homopolymers such as styrene and methyl methacrylate, and copolymers thereof.

  Examples of the lubricant include particles of a higher fatty acid metal salt. Examples of the higher fatty acid metal salt include zinc stearate, aluminum, copper, magnesium, calcium salts, zinc oleate, manganese. , Iron, copper, magnesium salts, zinc palmitate, copper, magnesium, calcium salts, zinc linoleate, calcium salts, and zinc ricinoleate, calcium salts.

  The content of the external additive in the toner particles is preferably 0.1 to 10.0% by mass. The toner particles can be formed by mixing the toner base particles and the external additive using a known mixing device such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.

  FIG. 1 is a diagram schematically illustrating an example of a configuration of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus includes a drum-shaped image carrier 10 that is rotatably arranged in the direction of arrow A, a charging device 11 for charging the surface of the image carrier 10, An exposure device 12 for exposing the surface of the image carrier 10 to form an electrostatic latent image, and a developing device 13 for making the electrostatic latent image visible with a developer containing toner particles to form a toner image. , A transfer device 14 for transferring the toner image formed on the image carrier 10 to the transfer material P, a separation device 15 for separating the transferred transfer material P from the image carrier 10, and an image carrier after transfer A cleaning device 20 for removing toner particles remaining on the body 10 and a fixing device 16 for fixing an unfixed toner image on the transfer material P to the transfer material P are provided. The charging device 11, the exposure device 12, the developing device 13, the transfer device 14, the separation device 15, and the cleaning device 20 are arranged along the direction of the arrow A in this order on the outer peripheral side of the image carrier 10.

  The cleaning device 20 includes a cleaning container 205 that opens toward the image carrier 10, and a cleaning blade 201 that is supported by the opening of the cleaning container 205 and contacts the surface of the image carrier 10. The cleaning blade 201 is supported at the opening by the support member at the base end so that the front end of the cleaning blade 201 contacts the surface of the image carrier 10. The direction extending from the base end side of the cleaning blade 201 to the image carrier 10 is a direction opposite to the rotation direction of the image carrier 10 (the movement direction of the surface), a so-called counter direction.

  As shown in FIG. 2, the cleaning blade 201 includes a plate member 210 having elasticity and a DLC film 220 that covers a part of the surface thereof. The plate-like member 210 is a rubber plate such as polyurethane rubber, for example. As described above, the DLC film 220 is a thin film made of a carbon-based material having both carbon-carbon bonds of both diamond and graphite (graphite).

  The plate-like member 210 has an edge portion 212, a first portion 214, and a second portion 216. The edge portion 212 is located on the image carrier 10 side when the cleaning blade 201 is disposed at a predetermined position with respect to the image carrier 10 among the two leading edges of the plate-like member 210. It is a front-end edge of the plate-shaped member 210 in the direction toward. The first portion 214 is a portion located upstream of the edge portion 212 in the arrow A direction when the cleaning blade 201 is disposed at a predetermined position with respect to the image carrier 10, and the plate-like member 210. It is the tip side of. The second portion 216 is located on the image carrier 10 side when the cleaning blade 201 is disposed at a predetermined position with respect to the image carrier 10 among the two side surfaces in the extending direction of the plate-like member 210. Surface.

  As shown in FIG. 3, the cleaning blade 201 is disposed so as to press the surface of the image carrier 10 through the DLC film 220 at the edge portion 212.

  The pressing force of the cleaning blade 201 against the image carrier 10 is preferably 17 to 35 N / m, and more preferably 21 to 30 N / m. When the pressing force is too low, toner particles slip through easily due to the insufficient pressing force. When the pressing force is too high, the frictional force between the cleaning blade 201 and the image carrier 10 is increased, and the cleaning blade 201 is easily worn.

  The contact angle of the cleaning blade 201 with the surface of the image carrier 10 is preferably a rigid contact angle of 10 to 30 °, and more preferably 15 to 27 °. Normally, the edge portion 212 is drawn in the rotation direction (arrow A direction), so that an appropriate cleaning nip portion is formed in the first portion 214. When the contact angle is too small, the cleaning blade 201 comes into contact with the surface of the image carrier 10 in the second portion 216, so-called “belly contact” state, and the first portion 214 passes the cleaning nip portion. Since the nip width tends to be large and the contact pressure decreases compared to the case of forming, toner particles may slip through. When the contact angle is too large, the edge portion 212 is likely to be pulled in the rotation direction, so that the edge portion 212 vibrates vigorously, so-called “squeal” may occur, and toner particles may slip through.

  Note that the rigid body contact angle is an image at a position where the extending direction of the cleaning blade 201 is in contact with the surface of the image carrier 10 when the cleaning blade 201 is regarded as a rigid body. This is the angle (θ in FIG. 1) formed with the tangent of the carrier 10.

  The image carrier 10 is charged by the charging device 11, and an electrostatic latent image is formed on the surface of the charged image carrier 10 by exposure of the surface by the exposure device 12. The electrostatic latent image becomes visible by supplying toner particles from the developing device 13 and becomes a toner image. The toner image formed on the image carrier 10 is transferred to the transfer material P by the transfer device 14. The transfer material P carrying the toner image is separated from the surface of the image carrier 10 by applying a voltage from the separation device 15. The toner image on the transfer material P is fixed to the transfer material P by heat and pressure by the fixing device 16.

  The toner particles remaining on the image carrier 10 after the transfer are conveyed by the image carrier 10 to a position where the cleaning device 20 faces. The blade cleaning of the image carrier 10 by the cleaning device 20 in the image forming apparatus will be described.

  As shown in FIG. 4, the cleaning blade 201 abuts the surface of the image carrier 10 at the edge portion 212 and a part of the first portion 214 on the upstream side thereof, and the cleaning nip portion (in FIG. 4). Nc). The transfer residual toner remaining on the surface of the image carrier 10 after the transfer is blocked by the cleaning blade 201 and forms a stationary layer 500 on the upstream side of the cleaning nip portion in the moving direction of the image carrier 10.

  The stationary layer 500 includes a surface (the surface of the DLC film 220 and the first portion 214) and the image of the cleaning blade 201 in contact with the surface of the image carrier 10, which is located upstream in the moving direction of the surface of the image carrier 10. This is a substantially wedge-shaped region formed between the surface of the carrier 10 and a collection of powders including the toner base particles 501 and the external additive 502 separated from the toner base particles 501. The length of the stationary layer 500 in the moving direction is generally 5 to 100 μm from the upstream end of the cleaning nip portion, although it varies depending on the printing rate of the image to be formed and the setting conditions of the cleaning blade 201.

  The toner particles blocked by the cleaning blade 201 convect at the position of the stationary layer 500. For this reason, friction between particles and friction between the particles and the cleaning blade 201 occur. Due to this friction, the external additive 502 is detached from the toner particles. Since the detached external additive 502 is smaller than the toner base particles 501, the external additive 502 is conveyed further downstream in the moving direction of the surface of the image carrier 10. Thus, the external additive 502 is concentrated in a narrower region in the stationary layer 500 on the downstream side in the moving direction.

  The toner particles and the toner base particles 501 are also dammed by the dense external additive 502, and gather on the upstream side and convect. The toner particles and the toner base particles 501 rub against each other and also rub against the surface of the cleaning blade 201.

  In the cleaning blade 201, the DLC film 220 is formed on a portion of the surface of the plate-like member 210 from the edge portion 212 to 10 to 100 μm, and on the portion from the edge portion 212 to 10 to 100 μm There is a boundary (an edge of the DLC film 220) between 220 and the surface of the plate-like member 210 (first portion 214). For this reason, the distance of the boundary from the upstream end of the cleaning nip portion is less than the length of the stationary layer 500.

  Therefore, toner particles and toner base particles 501 that convect in the static layer 500 also rub against the surface of the plate-like member 210. The plate-like member 210 is a rubber plate, for example, and has a sufficiently large frictional resistance as compared with the DLC film 220. Accordingly, the external additive 502 is more easily separated from the toner particles in the static layer 500, and the denseness of the external additive 502 on the downstream side of the static layer 500 is easily grown and maintained. Furthermore, the fluidity of the particles on the upstream side of the stationary layer 500 tends to be lowered.

  The particle group having decreased fluidity on the upstream side of the stationary layer 500 is scraped off from the surface of the image carrier 10 by the elasticity of the cleaning blade 201 and is stored (dropped) in the cleaning container 205. Thus, the toner particles are removed from the surface of the image carrier 10 without passing through the cleaning nip portion, and the image carrier 10 is subjected to blade cleaning.

  In general, when an image with a low printing rate is formed, there is little transfer residual toner, so that the stationary layer 500 is difficult to be formed and is not sufficiently developed. However, in the present embodiment, the stationary layer 500 is easily developed and maintained due to the friction between the particles in the stationary layer 500 and the plate-like member 210. Therefore, even when images with a low printing rate are continuously formed. It is possible to prevent toner from slipping through.

  As described above, in the present embodiment, the length from the edge portion 212 on the upstream side of the DLC film 220 is limited to a very short specific range, and therefore, the surface of the image carrier 10 and the first portion. The edge of the DLC film 220 is located in the stationary layer 500 formed between the layer 214 and the stationary layer 500. For this reason, the portion of the plate-like member 210 constituting the cleaning blade 201 that is not covered with the DLC film 220 comes into contact with the particles in the stationary layer 500 and affects the flow state of the particles in the stationary layer 500, As a result, poor cleaning due to insufficient development of the stationary layer 500 is improved. Therefore, the above-described excellent cleaning properties are exhibited.

  As is clear from the above description, the cleaning blade 201 according to the present embodiment is arranged on the plate member 210 having elasticity and including the edge portion 212 and on the surface including the edge portion 212 of the plate member 210. The cleaning blade has a DLC film 220 and contacts the surface of the image carrier 10 via the DLC film 220 at least at the edge portion 212 to remove deposits from the surface of the image carrier 10. The DLC film 220 is located at least upstream from the edge portion 212 in the moving direction of the surface of the image carrier 10 with respect to the edge portion 212 when the cleaning blade 201 contacts the surface of the image carrier 10. The position of the edge of the DLC film 220 disposed on the first portion 214 and on the first portion 214 is 10 to 100 μm from the edge portion 212.

  The image forming apparatus of the present embodiment also includes an image carrier 10 for carrying and transferring a toner image, and a toner remaining on the surface in contact with the surface of the image carrier 10 after the toner image is transferred. A cleaning blade 201 for removing particles from the surface. Further, in the image forming method of the present embodiment, the toner particles remaining on the surface of the image carrier 10 after transferring the toner image carried thereon are removed from the surface by the cleaning blade 201 in contact with the surface. Including a cleaning step.

  Therefore, according to the present embodiment, toner slippage can be suppressed even when images with a low printing rate are continuously output in electrophotographic image formation.

  The position of the edge of the DLC film 220 on the first portion 214 is 50 μm or less from the edge portion 212 from the viewpoint of improving the friction resistance between the particles in the stationary layer 500 and the plate-like member 210 and improving the cleaning property. The position is more effective, the position of 40 μm or less from the edge part 212 is even more effective, and the position of 25 μm or less from the edge part 212 is more effective.

  Further, the position of the edge of the DLC film 220 on the first portion 214 is more effectively 15 μm or more from the edge portion 212 from the viewpoint of preventing the cleaning blade 201 from lifting from the cleaning nip portion. Is.

  Further, the thickness of the DLC film 220 being 1 μm or more is more effective from the viewpoint of suppressing the wear of the DLC film 220 accompanying long-term use and the accompanying peeling of the DLC film 220.

[Production of Cleaning Member 1]
The cleaning member was removed from the drum unit of the image forming apparatus “bizhub Pro C1100” (manufactured by Konica Minolta, Inc., “bizhub” is a registered trademark of the company). As shown in FIG. 5A, the cleaning member is composed of a plate member 210 made of polyurethane rubber and a metal support member 230 that supports the plate member 210 on the base end side. The metal constituting the support member 230 has conductivity, and the plate-like member 210 is bonded to the support member 230. The plate-like member 210 of the present embodiment has a rectangular parallelepiped shape of 34 mm × 2 mm × 10 mm.

  As shown in FIG. 5A, the cleaning member was fixed by screws 304 and 305 to molds 301 to 303 capable of exposing one edge portion 212 on the front end side of the plate-like member 210 and its periphery. The mold 301 is a part on which the entire cleaning member is placed, and the cleaning member is fixed to the mold 301 by screws 305. The mold 302 is a part that comes into contact with the front end surface of the plate-like member 210, and is fixed to a desired position in the short direction of the mold 301 with a screw 304. The mold 303 is a part that abuts against one surface of the plate-like member 210 and is fixed at a desired position in the longitudinal direction of the mold 301.

  As shown in FIG. 5B, the plate-like member 210 has its tip surface surrounded by a broken line in FIG. 5B exposed from the mold from the edge portion 212 to the position of the length L <b> 1. One surface of 210 is exposed from the mold from the edge 212 to the position of the length L2. Here, L1 is 20 μm and L2 is 100 μm.

  Next, the cleaning member and the mold on which the cleaning member was fixed were accommodated in a chamber of a plasma CVD apparatus of a high frequency, high voltage pulse superposition type.

  Next, the surface of the plate member 210 exposed from the mold was subjected to surface cleaning. The chamber was filled with argon gas, and a high frequency pulse of 13.6 MHz and 1 to 3 kW and a high voltage pulse of −5 to −10 kV were superimposed on the mold. Thereby, argon plasma was inject | poured into said exposed part, and the deposit | attachment of the surface of the said part was removed.

  Next, an adhesive layer was formed on the exposed portion. The chamber was filled with methane gas, and a high frequency pulse of 13.6 MHz and 1 to 3 kW and a high voltage pulse of −4 to −8 kV were superimposed on the mold. Thereby, hydrocarbon plasma was injected into the exposed portion, and an adhesive layer was formed on the exposed portion.

  Next, a DLC film was formed on the adhesive layer. The chamber was filled with methane gas, and a high frequency pulse of 13.6 MHz and 1 to 3 kW and a high voltage pulse of −1.5 to −3 kV weaker than the above process were superimposed on the mold. Thus, hydrocarbon plasma was deposited on the adhesive layer without being injected into the exposed portion and without destroying the adhesive layer. In this way, a DLC film was formed on the exposed portion, and the cleaning member 1 was obtained. When the cross section of the tip portion including the edge portion 212 in the plate-like member of the cleaning member 1 was observed with a laser microscope, the thickness of the DLC film was 1.5 μm.

[Production of Cleaning Member 2]
A cleaning member 2 was prepared in the same manner as the cleaning member 1 except that the output time of the high frequency pulse and the high voltage pulse in the formation of the DLC film was changed. The film thickness of the DLC film in the cleaning member 2 was 1.1 μm.

[Preparation of cleaning members 3, 4, C2, C5 and C6]
Cleaning members 3, 4, C2, C5 and C6 were prepared in the same manner as the cleaning member 1 except that the position of the mold 302 was adjusted and L1 was changed to 24 μm, 16 μm, 8 μm, 255 μm and 503 μm, respectively. did.

[Preparation of cleaning members 5 to 13, C1 and C3]
Cleaning is performed in the same manner as the cleaning member 1 except that the position of the mold 302 is adjusted to change L1 to 21 μm and the output time of the high-frequency pulse and the high-voltage pulse in the formation of the DLC film is changed. Member 5 was produced. The film thickness of the DLC film in the cleaning member 5 was 0.9 μm.

  Also, the cleaning member 5 was prepared in the same manner as the cleaning member 5 except that the position of the mold 302 was adjusted and L1 was changed to 27 μm, 39 μm, 13 μm, 10 μm, 43 μm, 49 μm, 56 μm, 99 μm, 108 μm and 1020 μm, respectively. 6-13, C1 and C3 were produced, respectively.

[Preparation of cleaning member C4]
The cleaning member “bizhub Pro C1100” was defined as a cleaning member C4.

[Evaluation]
(1) Cleanability 1
The cleaning members of the image forming apparatus “bizhub Pro C1100” were replaced with the cleaning members 1 to 13 and C1 to C6, respectively. The contact load of the cleaning blade to the surface of the image carrier (photosensitive member) was set to 28 N / m, and the rigid contact angle was set to 20 °.

  Next, as shown in FIG. 6, an image chart with a printing rate of 3% in which one line drawing is formed on the entire width of the recording medium in a direction crossing the conveyance direction indicated by the arrow in FIG. 6 of the recording medium. Double-sided printing was continuously performed on 100,000 sheets of recording medium A (A3 size J paper; Konica Minolta Business Solutions Co., Ltd.). More specifically, the image chart has one band having a width of 12.6 mm in a direction perpendicular to the conveyance direction. The temperature and humidity conditions during printing were low temperature and low humidity conditions (temperature 10 ° C., humidity 20% RH) where slip-through is likely to occur.

  After the printing, the drum unit of the image forming apparatus is taken out, the surface of the photoreceptor and the surface of the recording medium A are visually observed, and the toner exists on the surface of the photoreceptor or a non-image portion of the recording medium A in a streak shape. The presence or absence of toner passing through was confirmed. The case where toner slip-through was not confirmed was passed, and the case where toner was confirmed was rejected.

(2) Cleanability 2
After the 100,000 sheets are printed, the photosensitive member is replaced with a new one, and the cleaning springs 1 to 13 and C1 to C6 are pressed by springs of the cleaning blade that urges the plate-like member toward the surface of the photosensitive member. The image chart was replaced with a spring having a different constant (pressing force on the plate member), and the image chart was further continuously printed on both sides of 100 sheets of recording medium A. Then, after printing, the presence or absence of toner slipping was confirmed in the same manner as in the evaluation of the cleaning property 1.

In this way, the minimum pressing force at which toner slip occurs was determined while changing the pressing force of the spring, and the pressing reduction rate Rd, which is an index value for cleaning performance, was determined from the following equation. The standard pressing force is 28 N / m in the evaluation of the cleaning property 1. The smaller the pressing force, the easier the toner slips out. The smaller the pressing force, the better the cleaning performance. A case where the pressure reduction rate exceeds 100% (those that slipped through even at a standard load) is rejected.
(formula)
Pressure reduction rate Rd (%) = {(minimum pressing force) / (standard pressing force)} × 100

(3) Wear width About each of the cleaning members 1-13 and C1-C6, the edge part 212 vicinity of the plate-shaped member after the said cleaning property 1 evaluation was observed by laser microscope observation, and the wear width was measured. More specifically, as shown in FIG. 7, the wear width is a line intersecting at 45 ° with respect to the surface of the front end portion of the plate-like member 210 in a cross section transverse to the longitudinal direction of the plate-like member 210. This is the distance (Wa) between the boundary between the upstream side surface and the downstream side surface and the portion lacking due to wear of the plate-like member in the direction parallel to the reference line. A wear width of 10 μm or less was accepted.

(4) Plastic deformation width About each of cleaning members 1-13 and C1-C6, the edge part 212 vicinity of the plate-shaped member after the said cleaning property 1 evaluation was observed by laser microscope observation, and the plastic deformation width was measured. The plastic deformation width is a width of a portion where the surface shape of the plate-shaped member is deformed although there is no chipping on the surface. Specifically, as shown in FIG. 8, the plastic deformation width crosses the longitudinal direction of the plate-shaped member 210. The length (Wpd) in the direction parallel to the reference line of the deformed portion of the front end surface of the plate-like member 210 in the cross section to which the angle with respect to the reference line becomes gentler than that of the front end surface. is there. A plastic deformation width of 10 μm or less was accepted.

  Table 1 shows the positions, thicknesses and evaluation results of the DLC films of the cleaning members 1 to 13 and C1 to C6.

  As is clear from Table 1, in any of the electrophotographic image formation using the cleaning members 1 to 13, no toner slip occurs. This is because the static layer generated at the time of cleaning is formed not only in the DLC film part but also in a position exceeding the boundary between the DLC film and the polyurethane rubber part, and the friction between the polyurethane rubber part and the toner particles in the static layer. This is thought to be because the external additive was removed from the toner base particles and the toner particles were easily detached from the surface of the photoreceptor.

  In particular, as apparent from the cleaning members 1 to 11, it is advantageous that the position of the boundary from the blade edge is 50 μm or less from the blade edge from the viewpoint of reducing the pressing force of the plate-like member against the surface of the photoreceptor. It is clear that the thickness is 40 μm or less from the viewpoint of suppressing plastic deformation in addition to the above viewpoint, and that it is more effective from the above viewpoint to be 25 μm or less.

  Further, as apparent from the cleaning members 2 and 5, the thickness of the DLC film being 1 μm or more means that the pressing force of the plate member against the surface of the photosensitive member is reduced, and the photosensitive member in the plate member. It turns out that it is much more effective from a viewpoint of suppressing the abrasion in the contact | abutting location to the surface.

  Further, as apparent from the cleaning members 4, 8 and 9, the fact that the position of the boundary is 15 μm or more away from the blade edge is a point of view to suppress wear at the contact portion of the plate-like member with the surface of the photoreceptor. It turns out that it is much more effective.

  On the other hand, in any of the electrophotographic image formation using the cleaning members C1 to C6, toner slip occurs. In image formation using the cleaning members C1, C3, C5, and C6, the position of the boundary from the blade edge is too far away, and the static layer is formed only at the portion where the DLC film abuts, and the friction against the toner particles is reduced. This is presumably because the external additive from the toner base particles in the stationary layer is insufficiently detached, and a part of the toner particles having sufficient fluidity due to the external additive slips through the cleaning nip portion.

  In the electrophotographic image formation using the cleaning member C2, the distance from the blade edge to the boundary in the DLC film is too short, and the part other than the DLC film (polyurethane rubber part) comes into contact with the surface of the photoreceptor. At this time, the DLC film is peeled off and the contact portion of the plate-like member is easily worn, and the convection of the toner particles in the stationary layer becomes strong, and the plate-like member is lifted from the surface of the photoreceptor. It is thought that it is easy to be released.

  Further, in the electrophotographic image formation using the cleaning member C4, since the cleaning member does not have the DLC film, the polyurethane rubber portion is in contact with the surface of the photoconductor, and the high hardness of the DLC film, This is probably because the wear of the blade edge portion progressed because the characteristics of low frictional resistance were not obtained, and the contact pressure of the plate-like member in the cleaning nip portion decreased.

  The cleaning blade exhibits bottom wear due to the slipperiness of the DLC film for the image carrier, and expresses a high frictional force of the plate-like member for particles in the stationary layer. Therefore, according to the present invention, even when an image with a low printing rate is formed, the static layer can be sufficiently maintained and developed, toner can be prevented from slipping through, and high quality and reliability in electrophotography. It is expected to contribute to the spread and development of high-quality image formation.

DESCRIPTION OF SYMBOLS 10 Image carrier 11 Charging device 12 Exposure device 13 Developing device 14 Transfer device 15 Separating device 16 Fixing device 20 Cleaning device 201 Cleaning blade 205 Cleaning container 210 Plate member 212 Edge portion 214 First portion 216 Second portion 220 DLC Film 230 Support member 301-303 Mold 304, 305 Screw 500 Static layer 501 Toner base particle 502 External additive A Arrow indicating the moving direction of the surface of the image carrier P Transfer material

Claims (8)

A plate-like member having elasticity and including an edge portion; and a diamond-like carbon film disposed on a surface of the plate-like member including the edge portion. In a cleaning blade for contacting the surface with at least the edge portion to remove the deposits from the surface of the image carrier,
The diamond-like carbon film is disposed at least from the edge portion to the first portion,
The first portion is a portion located upstream of the edge portion in the moving direction of the surface of the image carrier when the cleaning blade contacts the surface of the image carrier.
The position of the edge of the diamond-like carbon film on the first portion is a position of 10 to 100 μm from the edge portion.
Cleaning blade.   The cleaning blade according to claim 1, wherein a position of an edge of the diamond-like carbon film on the first portion is a position of 50 μm or less from the edge portion.   2. The cleaning blade according to claim 1, wherein a position of an edge of the diamond-like carbon film on the first portion is a position of 40 μm or less from the edge portion.   2. The cleaning blade according to claim 1, wherein a position of an edge of the diamond-like carbon film on the first portion is a position of 25 μm or less from the edge portion.   5. The cleaning blade according to claim 1, wherein a position of an edge of the diamond-like carbon film on the first portion is a position of 15 μm or more from the edge portion.   The cleaning blade according to claim 1, wherein the diamond-like carbon film has a thickness of 1 μm or more. An image carrier for carrying and transferring a toner image, and a cleaning blade for removing toner particles remaining on the surface in contact with the surface of the image carrier after the toner image is transferred. In an electrophotographic image forming apparatus having
The image forming apparatus, wherein the cleaning blade is the cleaning blade according to claim 1. An electrophotographic image forming method comprising a cleaning step of removing toner particles remaining on a surface of an image carrier after transferring a toner image carried thereon from the surface by a cleaning blade in contact with the surface. ,
For the cleaning blade, using the cleaning blade according to any one of claims 1 to 6,
An image forming method, wherein an edge of the diamond-like carbon film is located in a stationary layer formed between a surface of the image carrier and the first portion.

Images