JP2005338412A - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus with which the electrostatic charge sound generated in performing electrostatic charge by applying a vibration voltage superimposed with a DC voltage and an AC voltage on an electrostatic charging member can be sufficiently reduced, the degradation in image quality can be sufficiently prevented and a damping material for reducing the electrostatic charge sound and a photoreceptor can be easily separated and an electrophotographic photoreceptor used for the same. <P>SOLUTION: The electrophotographic photoreceptor is equipped with a cylindrical substrate 20 and the damping material 24 arranged on the inner side of the cylindrical substrate 20, wherein the damping material 24 contains a gelatinous material composed of silicone as a principal component and comes into tight contact directly with an inner peripheral surface 20a of the cylindrical substrate 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and an electrophotographic photosensitive member used therefor, and more specifically, to an image forming apparatus that applies an oscillating voltage obtained by superimposing a DC voltage and an AC voltage and charges the electrophotographic photosensitive member. The present invention relates to an electrophotographic photoreceptor to be used.

  Conventionally, as an image forming apparatus such as an electrophotographic apparatus (a copying machine, a printer, etc.), an electrostatic recording apparatus, etc., as a means for performing a neutralization process on a latent image carrier such as a photoconductor and a dielectric, and other charged objects In general, a non-contact type charging means that uses a corona discharge device and exposes the surface of an object to be charged to the generated corona is common.

  In recent years, since the power supply can be reduced in pressure and has the advantage that ozone is generated in a very small amount, a roller-type or blade-type conductive member is brought into contact with a charged body as a charging member. Contact charging means for charging the surface of the member to be charged by applying a voltage to the charging member in proximity to each other is adopted in a relatively low-speed model and has become mainstream.

  As such contact or proximity charging means, a DC application method in which only a DC voltage is applied to the charging member for charging treatment, and an oscillating voltage by superimposing an AC voltage and a DC voltage (the voltage value periodically changes with time). There is a DC + AC application method in which a charging process is performed by applying a voltage.

  However, the DC + AC application type contact or proximity charging means is an effective means for uniformly charging the object to be charged, but it causes a problem of so-called “charging noise”.

  That is, due to the alternating voltage component of the oscillating voltage applied to the contact or proximity charging member, a charging sound is generated when the charged body and the charging member vibrate and strike each other. This charged sound seems to be annoying, and it can be said that countermeasures are indispensable in recent years, with the demand for noise reduction in office machines such as copiers and printers.

  Attempts to reduce charging noise by inserting a filler inside the electrophotographic photosensitive member base have been studied (Patent Documents 1 to 3 below). However, in Patent Documents 1 to 3, the charging noise is not sufficiently reduced because the filler is not sufficiently fixed. On the other hand, when the filler is fixed with an adhesive or the like, it is difficult to separate the photoreceptor from the filler, which is inconvenient from the viewpoint of reproduction and reuse. Further, if the weight of the filler is increased, the rotational drive gear may be worn, although there is a vibration damping effect.

There is also an attempt to reduce the charged sound by processing the photoreceptor substrate itself without using a filler (Patent Documents 4 and 5 below). Even in this method, a sufficient effect of reducing the charging noise cannot be obtained depending on the material used for the photoreceptor substrate.
JP-A-5-197321 JP 11-184308 A JP 2000-321929 A JP 2000-19761 A JP 2000-155500 A

  The present invention has been made in view of the above circumstances, and sufficiently reduces the charging noise generated when charging is performed by applying an oscillating voltage in which a DC voltage and an AC voltage are superimposed on a charging member. It is an object of the present invention to provide an image forming apparatus that can sufficiently prevent a decrease in the noise and easily separate a vibration damping material and a cylindrical substrate for reducing charged noise, and an electrophotographic photoreceptor used therefor.

  The above object is achieved by the present invention described below.

  That is, the present invention provides an electrophotographic photosensitive member comprising a cylindrical substrate and a vibration damping material disposed inside the cylindrical substrate, wherein the vibration damping material includes a gel material mainly composed of silicone, The electrophotographic photosensitive member is in close contact with the inner peripheral surface of the cylindrical substrate.

  According to the electrophotographic photoreceptor according to the present invention, the electrophotographic photoreceptor according to the present invention is used as the electrophotographic photoreceptor constituting the image forming apparatus, and direct current and alternating current are superimposed on the surface of the electrophotographic photoreceptor. Even when an oscillating voltage is applied to charge the surface of the electrophotographic photosensitive member, the vibration damping material contains the gel material and is in close contact with the inner peripheral surface of the cylindrical substrate. It is fully absorbed by the damping material. Further, the damping material is in direct contact with the inner peripheral surface of the cylindrical base body with a pressing force applied, and the gel material has a small frictional resistance compared to an elastic body such as rubber. For this reason, a damping material and a cylindrical base | substrate can be isolate | separated easily.

  In the electrophotographic photoreceptor, it is preferable that the vibration damping material has a gel layer containing the gel material and is provided along the inner peripheral surface of the cylindrical base.

  In this case, the adhesion between the damping material and the cylindrical substrate is improved by the elastic force of the gel layer. For this reason, the charging noise is more sufficiently reduced.

  In the electrophotographic photosensitive member, the vibration damping material further includes an elastic layer, the elastic layer is provided on the inner side of the gel layer with respect to the cylindrical substrate, and the inner periphery of the cylindrical substrate is interposed via the gel layer. It is preferable to apply a pressing force to the surface.

  In this case, the adhesion between the gel layer and the cylindrical substrate is sufficiently improved by the elastic layer as compared with the case where the damping material does not have the elastic layer. For this reason, the charging sound generated during charging can be more sufficiently reduced. The gel layer and the elastic layer may be adjacent to each other or may not be adjacent to each other.

  In the electrophotographic photoreceptor, the gel layer is a foam, and the gel material contains a cross-linked product of an ethylene vinyl acetate copolymer and a silicone-modified ethylene vinyl acetate copolymer constituting a matrix. Is preferred. In this case, the gel layer is a foam, and the voids contained inside suppress the charged sound more effectively.

  In the vibration damping material, the gel layer is added with 5 to 50 parts by weight of the silicone-modified ethylene vinyl acetate copolymer with respect to 100 parts by weight of the total of the ethylene vinyl acetate copolymer and the silicone-modified ethylene vinyl acetate copolymer. A first step of adding a foaming agent and a crosslinking agent and kneading to obtain a kneaded product, a second step of obtaining a foam by heating and compressing the kneaded product at a temperature equal to or higher than the decomposition temperature of the foaming agent, It is preferable that the foam is manufactured by a process including a third process of processing and molding the foam to obtain a gel layer.

  In this case, the gel layer has excellent impact buffering properties and is reduced in weight.

  In the said 1st process, the compounding quantity of a silicone modified ethylene vinyl acetate copolymer is 10-40 weight part among the total 100 weight part of an ethylene vinyl acetate copolymer and a silicone modified ethylene vinyl acetate copolymer. It is more preferable.

  The present invention also provides the electrophotographic photosensitive member, charging means for charging the surface of the electrophotographic photosensitive member by applying an oscillating voltage in which direct current and alternating current are superimposed on the surface of the electrophotographic photosensitive member, and the electrophotographic photosensitive member. Image forming comprising at least one image forming unit including at least an exposure unit that exposes a charged region on the surface of a photographic photosensitive member to form a latent image and a developing unit that develops the latent image. Device.

  According to this image forming apparatus, even in the case where the surface of the electrophotographic photosensitive member is charged by applying an oscillating voltage in which direct current and alternating current are superimposed on the surface of the electrophotographic photosensitive member by the charging means in the image forming unit. Since the vibration material contains the gel-like material and is in close contact with the inner peripheral surface of the cylindrical substrate, the charging sound generated during charging is sufficiently absorbed by the vibration damping material without reducing the AC frequency. . Further, since the damping material is in direct contact with the inner peripheral surface of the cylindrical base body with a pressing force applied, the damping material and the cylindrical base body can be easily separated.

  According to the electrophotographic photosensitive member and the image forming apparatus of the present invention, since the charging sound generated during charging is sufficiently absorbed, the charging sound can be sufficiently reduced. Further, since the damping material is in direct contact with the inner peripheral surface of the cylindrical substrate, the damping material and the cylindrical substrate can be easily separated, and the photoreceptor is recycled and reused. The vibration material can be reused.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments. In all the drawings, the same or equivalent components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention, and shows a schematic configuration of an image forming apparatus having only an image forming unit for forming an image of a predetermined color on a sheet.

  As shown in FIG. 1, the image forming apparatus 100 includes an image forming unit 50 and a conveyance belt 51 that conveys the sheet 1 as a recording sheet to the image forming unit 50. The image forming unit 50 forms an image of a predetermined color on the paper 1 transported by the transport belt 51.

  The image forming unit 50 superimposes direct current and alternating current between the cylindrical electrophotographic photosensitive member 2 that is a latent image carrier, the charging roll 4 that is a charging unit, and the electrophotographic photosensitive member 2 and the charging roll 4. A charging bias applying power source 5 for applying the oscillating voltage, an exposure device 6 capable of exposing the surface of the electrophotographic photosensitive member 2 imagewise, and an electrostatic latent image formed by exposure by the exposure device 6 On the surface of the electrophotographic photoreceptor 2, a developing device 8 that can form an image by developing the toner, a transfer roll 10 as a transfer unit that transfers the image obtained by the developing device 8 to a sheet 1 that is a transfer medium. It comprises a cleaning blade 12 as a mechanical cleaning means for removing residual contaminants such as transfer residual toner and cleaning the surface of the electrophotographic photosensitive member 2.

  The pair of charging rolls 4, the exposure device 6, the developing device 8, the transfer roll 10, and the cleaning blade 12 are sequentially arranged along the circumferential direction of the electrophotographic photoreceptor 2.

  The charging roll 4 is biased with a pressing force against the surface of the electrophotographic photosensitive member 2 by a spring (not shown). The charging roll 4 is rotatably attached to the spring. Therefore, the charging roll 4 is driven to rotate at the same peripheral speed as the electrophotographic photosensitive member 2 due to friction with the electrophotographic photosensitive member 2 without any driving means, and functions as a contact charging unit. Note that some driving means may be attached to the charging roll and rotated at a peripheral speed different from that of the electrophotographic photosensitive member 2.

  A vibration voltage is applied between the electrophotographic photosensitive member 2 and the charging roll 4 by a charging bias application power source 5 so that the surface of the electrophotographic photosensitive member 2 is uniformly charged. In general, the voltage applied to the charging means includes a DC voltage or an oscillating voltage in which an AC voltage is superimposed on the DC voltage.

  The electrophotographic photosensitive member 2 is rotationally driven by a driving member or a driving system (not shown). As shown in FIG. 2, the electrophotographic photosensitive member 2 is provided along a cylindrical base 20, a photosensitive layer 22 provided on the outer peripheral surface side of the cylindrical base 20, and an inner peripheral surface 20a of the cylindrical base 20. The vibration damping material 24 is provided. Here, the damping material 24 will be described. The cylindrical substrate 20 and the photosensitive layer 22 will be described later.

  The damping material 24 is a plate-like member composed of a gel layer 28 provided along the inner peripheral surface 20a of the cylindrical base 20 and an elastic layer 30 provided inside the gel layer. Is provided along the inner peripheral surface 20 a of the cylindrical base 20.

  The gel layer 28 is in direct contact with the inner peripheral surface 20a of the cylindrical substrate 20. The gel layer 28 includes a gel material mainly composed of silicone having excellent sound absorption. Specifically, the gel material contains a cross-linked product of an ethylene vinyl acetate copolymer and a silicone-modified ethylene vinyl acetate copolymer constituting the matrix.

  The gel layer 28 is a foam and has a large number of voids. The foam may be in the form of open cell, closed cell or semi-closed cell.

  The elastic layer 30 applies a pressing force to the inner peripheral surface 20a through the gel layer 28 due to its elastic force.

  Next, a process of forming an image on the paper 1 by the image forming apparatus 100 having the above configuration, that is, an image forming method using the image forming apparatus 100 will be described.

  First, the electrophotographic photosensitive member 2 is rotationally driven by a driving member or a driving system (not shown) at a predetermined peripheral speed (process speed) in the clockwise direction (arrow A direction) in the drawing. Then, the charging roll 4 rotates following the rotation of the electrophotographic photosensitive member 2, and a vibration voltage is applied to each of the charging rolls 4 by the charging bias application power source 5. Uniformly charged to polarity and potential. At this time, the waveform of the superimposed alternating voltage includes a sine wave, a rectangular wave, a triangular wave, a pulse wave, and the like, but from the viewpoint of ease of application including manufacturing costs, a harmonic component is not included. A sine wave is preferred. The magnitude and frequency of the applied oscillating voltage are as follows. That is, the DC voltage is preferably positive or negative 50 to 2,000 V, particularly preferably 100 to 1,500 V, depending on the required charging potential of the electrophotographic photosensitive member 2. The alternating voltage to be superimposed is preferably such that the peak-to-peak voltage is 400 to 3,000 V, more preferably 800 to 2,500 V, and still more preferably 1,200 to 2,500 V. The frequency of the AC voltage is 50 to 20,000 Hz, preferably 100 to 5,000 Hz.

  Next, the surface of the electrophotographic photosensitive member 2 that has been charged is exposed by the exposure device 6, and an electrostatic latent image corresponding to target image information is formed on the surface of the electrophotographic photosensitive member 2.

  Subsequently, the electrostatic latent image is developed as a toner image by the developing device 8.

  On the other hand, the paper 1 is carried on the transport belt 16 and fed from a paper feed mechanism (not shown).

  Then, the tip of the toner image formed on the surface of the electrophotographic photosensitive member 2 at a predetermined timing, that is, at the transfer portion, is transferred to a transfer portion which is a pressure nip portion between the electrophotographic photosensitive member 2 and the transfer roll 10. It is inserted at the timing when the predetermined position of the recording paper matches. Thus, the toner image formed on the surface of the electrophotographic photosensitive member 2 is transferred onto the surface of the paper 1. The sheet 1 on which the toner image is formed is separated from the surface of the electrophotographic photosensitive member 2 and is conveyed to a fixing unit (not shown) to undergo a toner image fixing process.

  As described above, the image forming apparatus 100 forms an image of a predetermined color on the surface of the paper 1. The surface of the electrophotographic photosensitive member 2 that has passed through the transfer portion and has finished transferring the toner image onto the paper 1 is cleaned by the cleaning blade 12 to remove residual contaminants such as transfer residual toner, and is cleaned to the next surface. It is used for image formation.

  In the image forming process, an oscillating voltage is applied to the charging roll 4 of the image forming apparatus 100 by the charging bias applying power source 5. At this time, in the vibration damping material 24, the gel layer 28 not only applies a pressing force to the inner peripheral surface 20 a of the cylindrical base body 20 by the elastic force, but the elastic layer 30 also passes through the gel layer 28. A pressing force is applied to the inner peripheral surface 20 a of the cylindrical base body 20. For this reason, the damping material 24 is sufficiently adhered to the inner peripheral surface 20 a of the cylindrical base body 20. Further, the gel material contained in the gel layer 28 is excellent in sound absorption. In addition, many voids contained in the foam also have a sound absorbing function. Therefore, the charging sound generated when the vibration voltage is applied is efficiently absorbed by the damping material 24, that is, the gel layer 28 and the elastic layer 30, and the sound is suppressed. Therefore, it is possible to sufficiently reduce the charging sound generated during charging without reducing the frequency of the oscillating voltage. Therefore, the charging sound can be sufficiently reduced without degrading the image quality of the obtained image.

  The gel material has a smaller coefficient of friction with respect to the cylindrical base body 20 than an elastic body such as rubber. Therefore, it is possible to easily separate the vibration damping material 24 from the cylindrical substrate 20 and the photosensitive layer 22 (hereinafter referred to as “photosensitive body main body” if necessary). Therefore, it is easy to regenerate the photosensitive body main body and reuse the vibration damping material 24, thereby saving energy and resources.

  The manufacturing process of the gel layer 28 includes a first process to a third process, but these processes can be separated and processed, or can be processed as a continuous integrated process. Moreover, a well-known foam manufacturing process can be added suitably other than the 1st-3rd process.

  In the first step, a silicone-modified ethylene vinyl acetate copolymer, a foaming agent and a cross-linking agent are added to and kneaded with the ethylene vinyl acetate copolymer serving as the base resin to obtain a kneaded product.

  In the above kneaded product, the silicone-modified ethylene-vinyl acetate copolymer may be contained in a non-uniform state in a partially dispersed state even in a uniformly dispersed state in the matrix. In addition, at the boundary portion between the ethylene vinyl acetate copolymer as the matrix and the silicone-modified ethylene vinyl acetate copolymer, the reaction product produced by the reaction of both components due to thermal history during the production process, The thing which the component and the said reaction product reacted further etc. may exist simultaneously.

  In the ethylene vinyl acetate copolymer, the ratio of ethylene units to vinyl acetate units in the copolymer is not particularly limited. The silicone-modified ethylene-vinyl acetate copolymer used in the first step is, for example, a kneaded product of an ethylene-vinyl acetate copolymer and silicone, with heating in the presence of a crosslinking agent and other additives as required. It can be manufactured by kneading and molding.

  The silicone used for the production of the silicone-modified ethylene-vinyl acetate copolymer is not particularly limited, and as the silicone, a general silicone having a saturated or unsaturated group bonded to a silicon atom can be used. Examples of such a saturated or unsaturated group include those in which a monovalent hydrocarbon group or a part thereof is substituted, such as an alkyl group such as a methyl group, an ethyl group, and a propyl group, a phenyl group, An aryl group such as a tolyl group, a cycloalkyl group such as a cyclohexyl group or a cyclopropyl group, a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, etc. can be mentioned, and further, a part of hydrogen atoms of these substituents May be substituted with a halogen atom, a cyano group, a mercapto group or the like.

  Further, the structure of the silicone may be any of linear, branched, cyclic, etc. Among these, a linear one is preferable. The viscosity is preferably 10 cSt or more at 23 ° C., particularly preferably 1,000 to 1,000,000 cSt. As for the compounding quantity of silicone, 20-300 weight part is preferable with respect to 100 weight part of ethylene vinyl acetate copolymers.

  As the crosslinking agent, for example, a difunctional diene can be used. Examples of such dienes include 1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, and the like. Can do. Moreover, an organic peroxide can also be used as another crosslinking agent. Examples of the organic peroxide include succinic acid peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, p-chlorobenzoyl peroxide, t-butylperoxyisobutyrate, t-butylperoxyisopropyl carbonate, dicumyl Peroxide, t-butyl peroxycumene, di-t-butyl peroxide and the like can be mentioned. The blending amount of the crosslinking agent is 0.5 to 30 parts by weight of diene and 1 part by weight of organic peroxide with respect to 100 parts by weight of the total amount of ethylene vinyl acetate copolymer and silicone-modified ethylene vinyl acetate copolymer. It is preferable that the amount does not exceed.

  As other additives which are optional components, pigments, antioxidants, fillers, ultraviolet absorbers and the like can be blended within a range that does not adversely affect the properties of the silicone-modified ethylene-vinyl acetate copolymer. When a silicone-modified ethylene-vinyl acetate copolymer obtained by blending a pigment as another additive is colored, a desired color portion can be scattered on the surface of the foam, so that a decorative effect can be obtained. .

  The kneading method is not particularly limited, and kneading is performed at a temperature at which the curing reaction by the crosslinking agent proceeds, usually 120 to 300 ° C., using a Banbury mixer, a twin screw extruder, a roll mill, a kneader, a Brabender plastograph, or the like. . Thereafter, in consideration of ease of handling and the like, it is preferable to form into a pellet or the like. As the silicone-modified ethylene vinyl acetate copolymer thus obtained, for example, trade name RK-020-01 (silicone content 50%, MI = 0.30, mp = 73) sold by Siegel Co., Ltd. ° C) can be used.

  The blending amount of the silicone-modified ethylene vinyl acetate copolymer in the first step is to give an excellent shock buffering property to the foam and to reduce the weight, so that the ethylene vinyl acetate copolymer and the silicone modified ethylene vinyl acetate copolymer The silicone modified ethylene vinyl acetate copolymer is preferably 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, and particularly preferably 20 to 30 parts by weight.

  As the crosslinking agent used in the first step, for example, an organic peroxide can also be used. Examples of the organic peroxide include dicumyl peroxide, 1,1-di-butylperoxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, n -Butyl-4,4-di (t-butylperoxy) valerate, 1,1-di (t-butylperoxy) cyclohexane, and the like. The amount of the crosslinking agent is preferably such that the organic peroxide does not exceed 1 part by weight when the ethylene vinyl acetate copolymer and the silicone-modified ethylene vinyl acetate copolymer are combined to 100 parts by weight.

  The foaming agent used in the first step may be either an organic or inorganic foaming agent. Examples of organic foaming agents include N, N′-dinitroso / pentamethylene / tetramine, azobisisobutyronitrile, azodicarbonamide, p, p′-oxybis (benzenesulfonyl hydrazide), and the like. Examples of the foaming agent include sodium bicarbonate and ammonium carbonate.

  In addition to these foaming agents, known foaming aids such as urea, borax, and organic acids can also be used. The blending amount of the foaming agent is 1 to 8 parts by weight when 100 parts by weight of the ethylene vinyl acetate copolymer and the silicone-modified ethylene vinyl acetate copolymer are combined in order to ensure a suitable foaming state, preferably The amount is 1.5 to 6 parts by weight, particularly preferably 2 to 5 parts by weight.

  The kneading method in the first step is not particularly limited. For example, using a Banbury mixer, twin screw extruder, roll mill, kneader, intermix, etc., the ethylene vinyl acetate copolymer and the silicone-modified ethylene vinyl acetate copolymer are melted and softened, usually at 60 to 180 ° C. That's fine. Thereafter, it is preferable to form into a sheet or the like in consideration of ease of handling.

  The second step is a step of obtaining a foam by heating and compressing the kneaded product obtained in the first step at a temperature equal to or higher than the decomposition temperature of the foaming agent. As the foaming operation in this step, for example, a method of filling a kneaded material, which is an object to be foamed, into an appropriate mold, and heating and compressing to a predetermined temperature can be used. The temperature at this time is set to be equal to or higher than the temperature at which the crosslinking agent and the foaming agent cause a decomposition reaction. The time at this time is determined in consideration of the size of the object to be foamed, etc., but is usually about several minutes to 50 minutes.

  The third step is a step of obtaining the gel layer 28 by processing and molding the foam obtained in the second step for an electrophotographic photosensitive member damping material. Examples of such a process include a process of cutting the foam into a desired size.

  The elastic layer 30 can apply a pressing force to the inner peripheral surface 20a of the cylindrical base body 20 via the gel layer 28 due to its elastic force. In other words, the elastic layer 30 needs to have a sufficient reaction force to be in close contact with the inner peripheral surface 20a of the cylindrical base body 20, and needs to be easily bent so that it can be attached to the inside of the cylindrical base body 20. It is. Furthermore, it is desirable that the elastic layer 30 does not corrode in consideration of reusing the material collected from the market.

  Specifically, the elastic layer 30 is preferably formed by bending a stainless steel plate, a phosphor bronze plate, an aluminum plate, or the like having a thickness of about 0.1 mm to 2 mm. In addition, instead of a stainless steel plate, phosphor bronze plate, and aluminum plate having a thickness of about 0.1 mm to 2 mm, a resin having a thickness of about 1 mm to 3 mm, for example, polyamide (PA), acrylonitrile-butadiene Styrene (ABS), polypropylene (PP), polyacetal (POM), polystyrene (PS), and the like can also be used.

  The damping material 24 can be obtained by bonding the gel layer 28 and the elastic layer 30 using, for example, an adhesive.

  Next, the components of the image forming unit 50 will be described more specifically.

  The electrophotographic photosensitive member 2 is obtained by forming a photosensitive layer on the outer peripheral surface of a cylindrical substrate. The base material of the electrophotographic photosensitive member 2 is basically not particularly limited as long as it can be formed into a cylindrical shape, but metals such as aluminum and stainless steel are preferable in consideration of moldability, workability, strength, and the like. It is.

  The photosensitive layer provided on the outer periphery of the substrate is not particularly limited, and a known photoconductive material may be formed by a known means. However, considering that the charging roll 4 is in contact with the photosensitive layer, a photosensitive layer having an organic photoconductive material formed on the basis of a resin is preferable. The photosensitive layer mainly composed of the organic photoconductive material includes a single-layer photosensitive layer having both functions of charge generation ability and charge transport ability, and a laminated photosensitive layer in which a plurality of layers separated from each other are laminated. In the image forming apparatus of the present invention, the photosensitive layer may have any structure, but a laminated photosensitive layer is generally used.

  It is desirable to provide an undercoat layer on the surface of the substrate. As the undercoat layer, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, Examples thereof include various resins such as silicon-based resins and melamine-based resins, and those obtained by adding a zirconium compound, a titanium compound, or the like to these resins.

  A photosensitive layer is provided on the outer periphery of the substrate (when an undercoat layer is provided on the surface of the substrate, the outer periphery of the undercoat layer is referred to hereinafter). The photosensitive layer is formed by applying a coating solution prepared by dispersing or mixing a charge generation material and / or a charge transport material, a binder resin, and a solvent to the outer periphery of the substrate and drying. Therefore, the photosensitive layer is composed of a charge generation material and / or a charge transport material and a binder resin.

  At this time, when a single-layer type photosensitive layer is formed, a coating solution prepared by dispersing or mixing a charge generating substance, a charge transporting substance, a binder resin and a solvent is applied to the outer periphery of the substrate and dried. Therefore, the photosensitive layer is composed of a charge generation material, a charge transport material, and a binder resin. On the other hand, when forming a laminated photosensitive layer, a charge generation layer forming coating solution prepared by dispersing or mixing a charge generation material, a binder resin and a solvent, and the charge transport material, the binder resin and A charge transport layer forming coating solution prepared by mixing a solvent is prepared separately, and these coating solutions are sequentially applied and dried on the outer periphery of the substrate. Therefore, the photosensitive layer includes a charge generation layer containing a charge generation material and a binder resin, and a charge transport layer containing a charge transport material and a binder resin.

  Examples of the charge generating substance include azo pigments, disazo pigments, quinone pigments, quinocyanine pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, phthalocyanine pigments, quinacridone pigments, pyrylium salts, azurenium salts, and trigonal selenium. It is done.

  Examples of the charge transport material include a polyaromatic compound such as anthracene, pyrene, phenanthrene, coronene, or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline in the main chain or side chain. And compounds having a skeleton of a nitrogen-containing cyclic compound such as hyadiazole and triazole, and other hole transporting materials such as hydrazone compounds.

  As the solvent (solvent) for preparing the coating solution, a solvent having high volatility and a vapor density larger than that of air is preferably used. For example, n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine N, N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, 4-methoxy-4-methylpentanone, dimethoxymethane, dimethoxyethane, 2,4-pentadione, anisole, methyl 3-oxobutanoate, monochlorobenzene, toluene , Xylene, chloroform, 1,2-dichloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, 1-butanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, Ruserusorubu, ethyl cellosolve, methyl cellosolve, and the like methyl cellosolve acetate.

  As a driving member for rotationally driving the electrophotographic photosensitive member 2, a member for driving transmission and bearings in the image forming apparatus 100 called a gear or a flange is used. Is provided at at least one of the ends. As materials for these members, metals such as aluminum, resin molded products such as polycarbonate, and the like are used in terms of moldability, workability, slidability, and durability.

  The charging roll 4 charges the surface of the electrophotographic photosensitive member 2 by applying a vibration voltage to the surface of the electrophotographic photosensitive member 2, and the charging roll 4 is made of an elastic material imparted with conductivity. Is preferred. The charging roll 4 is usually configured by forming an elastic layer on the surface of a roll body as a core material and further forming a resistance layer thereon. Furthermore, a protective layer can be provided outside the resistance layer as necessary.

  The material of the roll body as the core material has conductivity, but generally iron, copper, brass, stainless steel, aluminum, nickel, etc. are used. In addition, as the material of the roll body, a resin molding material in which conductive particles or the like are dispersed can be used. As the material of the elastic layer, an elastic material having conductivity or semiconductivity is used. Generally, a rubber material in which conductive particles or semiconductive particles are dispersed is used.

  As the rubber material, EPDM, polybutadiene, natural rubber, polyisobutylene, SBR, CR, NBR, silicone rubber, urethane rubber, epichlorohydrin rubber, SBS, thermoplastic elastomer, norbornene rubber, fluorosilicone rubber, ethylene oxide rubber, etc. are used. .

Examples of the conductive particles or semiconductive particles include carbon black, zinc, aluminum, copper, iron, nickel, chromium, titanium, and other metals, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O _3. Metal oxides such as —SnO ₂ , ZnO—TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , Sb ₂ O ₃ , In ₂ O ₃ , ZnO, MgO can be used. These materials may be used alone or in combination of two or more.

The resistance layer and the protective layer are obtained by dispersing conductive particles or semiconductive particles in a binder resin and controlling the resistance. As the binder resin, acrylic resin, cellulose resin, polyamide resin, methoxymethylated nylon Ethoxymethylated nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, polythiophene resin, polyolefin resin such as PFA, FEP, PET, styrene butadiene resin and the like are used. As the conductive particles or semiconductive particles, the same carbon black, metal, and metal oxide as the elastic layer are used. The resistivity of the resistance layer and the protective layer is preferably 10 ³ to 10 ¹⁴ Ωcm, more preferably 10 ⁵ to 10 ¹² Ωcm, and further preferably 10 ⁷ to 10 ¹² Ωcm. The film thickness of the resistance layer and the protective layer is
Preferably it is 0.01-1,000 micrometers, More preferably, it is 0.1-500 micrometers, More preferably, it is 0.5-100 micrometers.

  Moreover, antioxidants, such as hindered phenol and hindered amine, fillers, such as clay and kaolin, and lubricants, such as silicone oil, can be added to a resistance layer and a protective layer as needed.

  The resistance layer and the protective layer can be formed by preparing a coating solution by dissolving and dispersing each of the above materials in an appropriate solvent and applying the coating solution to an object to be coated. As a means for applying, conventionally known means such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method can be employed.

  The exposure device 6 can expose the surface of the electrophotographic photosensitive member 2 imagewise to form an electrostatic latent image. Examples of the exposure device 6 include conventionally known laser beam scanning exposure means, Examples thereof include slit exposure means, and any of these can be applied.

  The developing device 8 is capable of forming an image by developing the latent image formed on the surface of the electrophotographic photosensitive member 2 by being exposed by the exposure device 6. Examples thereof include a developing unit using powder toner.

  As the transfer roll 10, conventionally known transfer means capable of copying an image of toner or the like developed by the developing device 8 onto the paper 1 is employed.

  The cleaning blade 12 is in direct contact with the surface of the electrophotographic photosensitive member 2 and mechanically removes residual contaminants such as toner, paper dust, and dust adhering to the surface. As the cleaning means, a blade type such as a cleaning blade shown in FIG. 1 is used, but other known types such as a brush and a roll can also be applied. The cleaning blade 12 may also be used as the charging roll 4. In this case, the charging roll 4 not only charges the surface of the electrophotographic photosensitive member 2 but also has a function of cleaning the surface of the electrophotographic photosensitive member 2.

  The fixing unit is not particularly limited as long as it can fix the image formed on the sheet 1 to the sheet 1, and any conventionally known fixing unit using heat and / or pressure, or fixing unit using a solvent, etc. A fixing unit can be employed depending on the purpose.

  The present invention has been described above with reference to the embodiments. However, the present invention merely shows an embodiment of an image forming apparatus and an image forming method to which the present invention can be applied, and the present invention is of course limited thereto. Instead, as long as the configuration of the present invention is provided, a specific member or the like can be replaced with a known member.

  Further, in the above embodiment, the case where the image forming apparatus of the present invention has one image forming unit has been described. However, the image forming apparatus of the present invention only needs to have at least one image forming unit. A plurality of image forming units may be provided. When the image forming apparatus of the present invention has four image forming units, four image images of yellow, magenta, cyan and black are formed by these four image units. If stacked on the paper 1, a full-color image can be formed.

  In the above embodiment, the transport belt 51 is used to transport the paper 1 to the image forming unit 50, but a transport drum may be used instead of the transport belt 51.

  Further, when the image forming apparatus of the present invention has a plurality of image forming units, belt-shaped or drum-shaped intermediate transfer members are used, and images of each color are transferred or laminated from the plurality of image forming units to the intermediate transfer member. A method of transferring to the surface of the paper 1 may be used.

  Furthermore, in the above-described embodiment, the damping material 24 is configured by the gel layer 28 and the elastic layer 30, but the damping material 24 may be configured by only the gel layer 28 (see FIG. 3). Even in this case, the gel layer 28 is directly adhered to the inner peripheral surface 20a of the cylindrical substrate 20 by its elastic force.

  Hereinafter, the present invention will be described more specifically with reference to examples.

(Example 1)
<Method for producing photoconductor>
An extruded aluminum tube having a material 1050 (JIS H4080, material symbol 1050), outer diameter φ84.5 mm × inner diameter φ82 mm × length 350 mm, prepared by extrusion and drawing was prepared. Both ends of the aluminum base tube were subjected to inlay processing having an inner diameter of φ82.5 mm and a depth of 10 mm, and at the same time, the total length was finished to 347 mm. Thereafter, the aluminum base tube was mirror-finished, the outer diameter was φ84 mm, and an aluminum substrate was obtained.

  On the outer peripheral surface of the aluminum substrate thus obtained, an undercoat layer, a charge generation layer and a charge transport layer were sequentially laminated as follows, and a photosensitive layer was formed to obtain an electrophotographic photoreceptor.

(1) Formation of undercoat layer Coating solution A having the following composition was applied to the surface of an aluminum substrate by a dipping method and dried at 150 ° C. for 10 minutes to form an undercoat layer having a dry film thickness of 1.0 μm. .
[Composition of coating liquid A]
-Zirconium compound represented by the following structural formula (1): 20 parts by weight-Silane coupling agent represented by the following structural formula (2): 2 parts by weight-Polyvinyl butyral resin represented by the following structural formula (3) : 2 parts by weight-1-butanol: 70 parts by weight

(2) Formation of charge generation layer Coating solution B obtained by dispersing a mixed solution having the following composition in a sand mill using glass beads of 1 mmφ for 5 hours was applied on the undercoat layer by a dipping method, and 100 The film was dried at a temperature of 10 ° C. for 10 minutes to form a charge generation layer having a dry film thickness of 0.2 μm.
[Composition of coating liquid B]
-Chlorgallium phthalocyanine: 5 parts by weight-Vinyl chloride-vinyl acetate copolymer represented by the following structural formula (4): 5 parts by weight-n-butyl acetate: 200 parts by weight

(3) Formation of charge transport layer On the charge generation layer, a coating liquid C having the following composition was applied by an immersion method and dried at 120 ° C. for 60 minutes to form a charge transport layer having a dry film thickness of 25 μm. .
[Composition of coating liquid C]
-Charge transport material represented by the following structural formula (5): 1 part by weight-Polycarbonate resin represented by the following structural formula (6): 1 part by weight-Monochlorobenzene: 2 parts by weight-Tetrahydrofuran: 4 parts by weight

  On the other hand, with respect to ethylene vinyl acetate copolymer (MI = 2.5, vinyl acetate unit content 19%; manufactured by Mitsui DuPont Polychemical Co., Ltd.), RK-020-01 was used as a silicone-modified ethylene vinyl acetate copolymer. 30 parts by weight of 100 parts by weight of all polymer components, 2 parts by weight of azodicarbonamide as a foaming agent, 1 part by weight of dicumyl peroxide as a crosslinking agent, 0.3 part by weight of polyethylene glycol as other additives, stearic acid Was blended at 70 to 110 ° C. for 10 minutes using a pressure kneader. Then, it roll-rolled at 80 degreeC and the sheet-like molded product was obtained.

  Next, the sheet-like molded product was heated and compressed at 150 ° C. for 30 minutes to obtain a closed cell foam having a thickness of 30 mm. Then, it shape | molded by cutting and obtained the damping material of thickness 30mm which the whole consists of the said foam.

  The damping material obtained in this way is cut out into 120 mm × 300 mm, rounded until the outer diameter is approximately 105 mm so that the 300 mm side is arcuate, and the inner wall portion of the photoconductor main body already prepared is The whole was crushed and inserted in the substantially central part in the axial direction. Thus, an electrophotographic photosensitive member was obtained. Subsequently, flanges were bonded to both ends of the electrophotographic photoreceptor using an adhesive to obtain a flanged electrophotographic photoreceptor. As the adhesive, a two-component mixed epoxy adhesive (produced by Cemedine; trade name EP-007) was used.

<Image forming apparatus>
A laser beam printer (manufactured by Fuji Xerox; DocuPrint C830) was prepared, and the electrophotographic photosensitive member obtained as described above was used in place of the electrophotographic photosensitive member. The charging roll is provided with a conductive elastic layer in which carbon black is dispersed in urethane rubber on the peripheral surface of a core metal made of stainless steel (made of SUS304) having an outer diameter of 6 mm, and N is formed on the surface of the conductive elastic layer. A layer composed of a methoxymethylated nylon layer as a protective layer and having an outer diameter of φ12 mm was used. Thus, an image forming apparatus was obtained.

Then, the image forming apparatus was operated to perform image formation. At this time, the AC applied voltage to the charging roll was as follows.
Waveform: sine wave,
Peak-to-peak voltage: 1.0 KV
Frequency: 1,110Hz

<Confirmation of effect of damping material>
The effect of the vibration damping material was confirmed by sensory evaluation by five arbitrarily extracted humans. Specifically, five people were asked to hear the charging sound when the image forming apparatus was operated, and the degree of the charging sound at that time was evaluated. At this time, 10 electrophotographic photoreceptors were evaluated. The results are shown in Table 1.

<Evaluation of image quality>
At the time of the evaluation of the charging sound, an image quality sample that outputs a 20% halftone at the same time was collected, and the presence or absence of density unevenness was confirmed. The results are shown in Table 1.

(Example 2)
An image forming apparatus was obtained in the same manner as in Example 1 except that a damping material was obtained as follows.

  That is, first, a closed cell foam having a thickness of 18 mm was obtained in the same manner as in Example 1. Thereafter, in the same manner as in Example 1, the closed-cell foam was molded to obtain a molded body. On the other hand, a stainless steel plate (SUS304) with t = 0.5 was prepared, and the stainless steel plate was bent so that the inner diameter R was 26 mm. And the said molded object was affixed on this stainless steel plate, and the damping material was obtained.

  In the same manner as in Example 1, charging sound and image quality were evaluated. The results are shown in Table 1.

(Comparative Example 1)
An image forming apparatus was obtained in the same manner as in Example 1 except that the damping material was not provided inside the cylindrical substrate. In the same manner as in Example 1, charging sound and image quality were evaluated. The results are shown in Table 1.

  From the results shown in Table 1, it was found that according to Examples 1 and 2, the charged sound was effectively suppressed and good image quality was obtained. On the other hand, according to Comparative Example 1, it was found that an unpleasant sound was generated although good image quality was obtained.

  From this, it was confirmed that according to the image forming apparatus of the present invention, the charging sound is effectively suppressed and a good image quality can be obtained. Further, since the damping material is inserted inside the cylindrical base and is made to adhere directly to the inner peripheral surface of the cylindrical base by its elastic force, the damping material and the cylindrical base can be easily separated. It is considered a thing.

1 is a schematic diagram showing an embodiment of an image forming apparatus of the present invention. 1 is a side view showing an embodiment of an electrophotographic photosensitive member of the present invention. It is a side view which shows other embodiment of the electrophotographic photoreceptor of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Electrophotographic photosensitive member, 4 ... Charge roll (charging means), 6 ... Exposure apparatus (exposure means), 8 ... Developing apparatus (developing means), 20 ... Cylindrical base | substrate, 20a ... Inner peripheral surface, 22 ... Photosensitive layer 24 ... Damping material, 28 ... Gel layer, 30 ... Elastic layer, 50 ... Image forming unit, 100 ... Image forming apparatus.

Claims (7)

In an electrophotographic photosensitive member comprising a cylindrical substrate and a damping material disposed inside the cylindrical substrate,
The electrophotographic photosensitive member, wherein the vibration damping material includes a gel-like material containing silicone as a main component, and is in direct contact with the inner peripheral surface of the cylindrical substrate.   The electrophotographic photosensitive member according to claim 1, wherein the vibration damping material has a gel layer containing the gel material, and is provided along the inner peripheral surface of the cylindrical substrate.   The damping material further includes an elastic layer, the elastic layer is provided on the inner side of the gel layer with respect to the cylindrical base, and a pressing force is applied to the inner peripheral surface of the cylindrical base via the gel layer. The electrophotographic photosensitive member according to claim 2, wherein   The gel layer is a foam, and the gel material contains a cross-linked product of an ethylene vinyl acetate copolymer and a silicone-modified ethylene vinyl acetate copolymer constituting the matrix. 3. The electrophotographic photosensitive member according to 3. The gel layer is
Add 5-50 parts by weight of silicone-modified ethylene-vinyl acetate copolymer to 100 parts by weight of the total of ethylene-vinyl acetate copolymer and silicone-modified ethylene-vinyl acetate copolymer, and add a foaming agent and a crosslinking agent. A first step of obtaining a kneaded product by kneading, a second step of obtaining a foam by heating and compressing the kneaded product at a temperature equal to or higher than the decomposition temperature of the foaming agent, and a gel layer by processing and molding the foam The electrophotographic photosensitive member according to claim 4, wherein the electrophotographic photosensitive member is manufactured by a process including a third step of obtaining   In the first step, among 100 parts by weight of the total of the ethylene vinyl acetate copolymer and the silicone modified ethylene vinyl acetate copolymer, the compounding amount of the silicone modified ethylene vinyl acetate copolymer is 10 to 40 parts by weight. The electrophotographic photosensitive member according to claim 5. The electrophotographic photosensitive member according to any one of claims 1 to 6,
Charging means for charging the surface of the electrophotographic photosensitive member by applying an oscillating voltage in which direct current and alternating current are superimposed on the surface of the electrophotographic photosensitive member;
Exposure means for exposing a charged region on the surface of the electrophotographic photosensitive member to form a latent image;
An image forming apparatus comprising at least one image forming unit including at least developing means for developing the latent image.

Images