JP4366180B2 - Endless belt for electrophotographic apparatus and manufacturing method thereof, belt cartridge, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an endless belt such as a transfer conveyance belt, an intermediate transfer belt, a photosensitive belt, and a fixing belt used in an electrophotographic apparatus.

  Conventionally, transfer end members, intermediate transfer members, electrophotographic photosensitive members, fixing members and the like used in electrophotographic apparatuses such as copying machines and laser beam printers have a flexible endless belt shape in addition to a rigid drum shape. Things (electrophotographic endless belts) are used.

  In recent years, full-color electrophotographic apparatuses have been put into practical use, and the number of production has been increasing year by year. Accordingly, the demand for intermediate transfer belts, transfer conveyance belts and the like has also increased.

  These endless belts have been proposed which are made of a thermosetting rubber, a thermosetting resin, a thermoplastic resin, or the like.

  As an example of using a thermosetting rubber as an endless belt for an electrophotographic apparatus, for example, Patent Document 1 is proposed. However, when such a thermosetting rubber is used, a process called vulcanization is required, which requires a lot of energy and time, leading to an increase in cost. Further, rubber has a low elastic modulus. For example, when used as an intermediate transfer belt, there is a problem in that the belt itself is stretched and color misregistration occurs. In addition, the creep resistance is poor, and when the belt is stretched on a roller, the belt gradually stretches, loosens, and cannot be used. Furthermore, since it was inferior in abrasion resistance, the surface was shaved and it was not durable.

  As an example of using a thermosetting resin as an endless belt for an electrophotographic apparatus, for example, Patent Document 2 is proposed. In this proposal, a thermosetting polyimide is exemplified. Thermosetting resins have the advantages of higher elastic modulus, excellent creep resistance, and wear resistance than the rubber materials described above. However, the material itself is very expensive, and it is necessary to dissolve the resin or resin precursor in an organic solvent or acid before molding. To mold these resins, centrifugal molding or dipping However, these methods have a problem that it takes time to form and it is difficult to reduce manufacturing costs. In addition, when a non-soluble filler is added to give desired characteristics, it leads to poor dispersion such as sedimentation or agglomeration, lack of uniformity of the belt, and tends to cause partial strength reduction and resistance variation. There was also a problem.

  As described above, when thermosetting rubber or resin is used as a material, there are many problems. As a means for solving these problems, a method using a material made of a thermoplastic resin has been proposed.

  As the thermoplastic resin, for example, a resin obtained by blending a conductive filler with polycarbonate (PC), polyethylene terephthalate (PET) or the like has been used.

  However, polycarbonate is an amorphous resin and is inferior in bending fatigue resistance. When used over a long period of time, there is a problem in that it cracks and eventually breaks, resulting in poor durability. Polycarbonate (PC) and polyethylene terephthalate (PET) have high polarity, and when used as an intermediate transfer belt or a transfer belt, the releasability from the toner was poor. This often causes problems such as toner filming.

  On the other hand, a crystalline resin such as polyethylene terephthalate (PET) is rich in bending resistance and excellent in durability, but has a large change in melt viscosity near the melting point and has difficulty in moldability. Due to the progress of crystallization, there is a problem that the dimensional change after molding is large and the dimensional stability is poor.

  However, both bending resistance and dimensional stability are characteristics required as an endless belt of an electrophotographic apparatus, and both are indispensable.

  In recent years, there has been an increasing demand for miniaturization of electrophotographic apparatuses for the purpose of saving the installation space. Therefore, the diameter of each roller used in the apparatus has been reduced, and the diameter of the roller that stretches and drives the belt is further reduced. When the roller for stretching the belt is reduced in diameter, the curvature of the belt is reduced and the required bending resistance is further increased. In addition, miniaturization and precision have been demanded. In the refinement, endless belts are also required to have higher dimensional accuracy and dimensional stability.

Despite demands for higher bending resistance, dimensional accuracy, and dimensional stability, the conventionally proposed endless belts do not sufficiently meet the requirements.
JP 2000-250328 A JP 2000-355432 A

  As described above, the conventionally proposed endless belt for an electrophotographic apparatus has a problem that both durability and dimensional stability cannot be achieved.

SUMMARY OF THE INVENTION In view of the above-described problems, inexpensive to manufacture, long-term without any crack or cracks also be used, durable, small endless electrophotographic apparatus of dimensional change belt after molding and The manufacturing method is provided.

  Another object of the present invention is to provide a belt cartridge, a process cartridge, and an image forming apparatus provided with the endless belt for an electrophotographic apparatus.

In accordance with the present invention, in the A acrylic resin, and rubber particles, and the conductive filler is a electrophotographic endless belt device having a layer comprising a resin composition dispersed, conductive filler, said acrylic resin An endless belt for electrophotography, characterized in that it is localized on the side, is provided.
Further, according to the present invention, an endless belt for an electrophotographic apparatus comprising a step of melt-molding a resin composition obtained by adding rubber particles and a conductive filler to an acrylic resin to form a cylindrical film A manufacturing method is provided .

  In addition, according to the present invention, there are provided a belt cartridge, a process cartridge, and an image forming apparatus provided with the endless belt for an electrophotographic apparatus.

As described above, according to the present invention, an endless belt for an electrophotographic apparatus that can be manufactured at low cost, has excellent creep resistance, flex resistance, dimensional stability, and can be used over a long period of time, and a method for manufacturing the same , It has become possible to provide a belt cartridge, a process cartridge, and an image forming apparatus provided with the endless belt for an electrophotographic apparatus.

  In order to achieve the above-mentioned object, the present inventors have intensively studied and studied the cause of cracks, cracks, and breakage of endless belts, and countermeasures thereof. As a result, so-called crystalline thermoplastic resins have relatively high bending resistance. It was found that the amorphous thermoplastic resin tends to be inferior in bending resistance.

  However, it has been found that even in an amorphous thermoplastic resin, the bending resistance is dramatically improved by adding a rubber component as in the present invention. In addition, the crystalline thermoplastic resin is inferior in bending resistance when the crystallinity is low due to a material having a relatively low crystallinity, a molding method, or a thermal history. Thus, it was found that the flex resistance was improved by adding the rubber component, and the present invention was completed.

  In the present invention, the thermoplastic resin is the main component, so there is no need for vulcanization or curing processes like thermosetting materials, continuous production is possible, manufacturing tact time can be shortened, and consequently inexpensive. There is an advantage that it can be manufactured. In addition, the thermoplastic resin has an extremely high elastic modulus as compared with a thermosetting rubber or the like, and there is almost no problem of elongation or creep.

  In the present invention, an acrylic resin is used among the thermoplastic resins. Acrylic resins are generally classified as general-purpose plastics, and can be molded at a relatively low temperature compared to general-purpose engineering plastics and super engineering plastics. They do not require a lot of energy for molding, and because they are general-purpose plastics, the unit price per kilogram is low. On the other hand, it has an appropriate mechanical strength and a relatively low water absorption rate, and in recent years when the cost of electrophotographic apparatuses has been reduced, it is very preferable to use such a resin as an endless belt.

  An acrylic resin is an amorphous resin, and its dimensional change over time due to crystallization is very small, and a stable dimension can be maintained over a long period of time.

  The acrylic resin in the present invention is an alias, and refers to all polymers called methacrylic resin, PMMA, and polymethyl methacrylate, and is a polymer mainly composed of methyl methacrylate (MMA). In addition to methyl methacrylate, acrylic acid Copolymers composed of monomers mainly composed of alkyl acrylate such as methyl, ethyl acrylate and butyl acrylate are also included in the acrylic resin of the present invention.

In the present invention, in addition to the acrylic resin, a rubber component is added to improve the bending resistance. Conventionally, it has been common to add a rubber component to a thermoplastic resin for the purpose of improving impact resistance. For example, HIPS (high impact polystyrene) or ABS (acrylonitrile-butadiene-styrene copolymer). Etc. can be illustrated. However, the impact resistance and the bending resistance as an endless belt are different from each other. According to the study by the present inventors, even if an endless belt is made using a material having excellent impact resistance, the bending resistance is not necessarily limited. The result that it was not necessarily excellent in the property was obtained.

In the present invention, rubber particles are added to improve the bending resistance, but the particle size of the rubber particles is preferably 0.05 μm to 10 μm in consideration of dispersibility in an acrylic resin as a binder. If it is less than 0.05 μm, the particle size is too small and the rubber particles tend to aggregate, and the dispersibility deteriorates. If it exceeds 10 μm, the particle size is too large and the rubber part and the resin part are separated too much, leading to a decrease in mechanical properties. The particle diameter of the rubber particles of the present invention refers to the primary particle diameter, and does not refer to the diameter of the aggregated particles in which the primary particles are aggregated.

Usually, an acrylic resin to which rubber particles are added has a structure in which the resin is a matrix and the rubber is a domain. The compounding ratio of the preferred resin and rubber component is in the range of 30:70 to 95: 5. If the resin component is more than 95%, the effect on the bending resistance due to the addition of the rubber component is insufficient. Conversely, if the rubber component is more than 70%, the domain rubber The resin that is a matrix that fills the space between particles is not sufficient, and not only the moldability is poor, but also the mechanical properties are close to rubber, which is not preferable because it stretches or creeps when used as a belt.

In the present invention, a rubber component is added to improve the bending resistance, but the method for adding the rubber component is not particularly limited. You may add at the time of polymer polymerization which is an acrylic resin, and you may mix with a rubber component after becoming a polymer.

  For example, as a method for producing an acrylic resin containing an acrylic rubber, it is common to graft emulsion polymerize an acrylate ester with MMA as the main component in the presence of the acrylic rubber.

  Further, the rubber component of the present invention may be a simple latex particle, but for the purpose of increasing the affinity with the resin, causing no deterioration in physical properties, and extracting the effect of the rubber particle more efficiently. Use a structure in which a polymer having affinity for the resin to be mixed is grafted on the particle surface, or a multilayer structure such as a so-called core-shell structure with a rubber core and a resin shell. Is preferred.

  Moreover, the kind of the rubber component added for improving the bending resistance is not particularly limited, but any rubber component can be used as long as the bending resistance can be improved. Examples thereof include butadiene rubber, styrene rubber, acrylic rubber, silicone rubber, and fluorine rubber. For example, a copolymer such as ethylene-propylene-diene or styrene-butadiene may be used. Alternatively, these rubbers may be used in combination. Among these, those containing acrylic rubber as a main component are preferable in terms of compatibility with acrylic resins. When more rubbery elasticity is required, it is preferable to use butadiene rubber particles.

  In particular, in the case of acrylic resin, when acrylic rubber is added, the refractive index is almost equal, and ABS resin, which is a thermoplastic resin to which rubber is added, is also opaque, whereas acrylic resin and acrylic rubber are The mixed material has transparency. For example, when this material is used as a photosensitive belt, there is a merit that a back exposure system or a photostatic system from the back of the belt can be adopted. Of course, when transparency is not necessarily required, other types of rubber particles may be used.

In the case of confirming the dispersion state of the rubber particles after forming into a belt after molding, there is no particular limitation. However, in some cases, an endless belt section is embedded with a resin, and this is made of RuO ₄ , phosphotungstic acid, or the like. A known method such as staining with TEM, preparing an ultrathin section, and observing with a TEM (Transmission Electron Microscope) can be used.

Usually, an acrylic resin is an insulating material itself and often does not function as an endless belt of an electrophotographic apparatus, and a conductive agent or an antistatic agent is added to adjust electric resistance. For example, examples of the conductive filler include carbon black and various conductive metal oxides, and examples of the non-filler resistance adjuster include low molecular weight ionic conductive agents such as various metal salts and glycols, ether bonds, and the like. Examples thereof include an antistatic resin containing a hydroxyl group in the molecule, an organic polymer compound exhibiting electronic conductivity, and the like. Accordingly, the additive to be mixed for adjusting the electric resistance value of the electrophotographic endless belt of the present invention is not particularly limited. Among these, carbon black is preferable because it is relatively inexpensive and can be adjusted in a small amount.

  Also, depending on the electrophotographic process, an ion conductive conductive agent may be more suitable than an electron conductive conductive agent such as carbon black. In such a case, a polymer conductive agent such as polyether ester, polyether amide, or polyether ester amide is preferable in that there is little bleeding out from the molded product.

Usually, a conductive agent such as carbon black is used, and there is an inflection point where the electrical resistance value suddenly decreases as the amount added is increased, stabilizing the medium resistance region required for the electrophotographic process. it is difficult to produce Te, but is localized in the acrylic resin side of the carbon black by adding a rubber component in the acrylic resin as in the present invention, the resistance control such as dilute a rubber component it By doing so, there is also a merit that a resin composition in the middle resistance region can be obtained very stably.

  Although there is no restriction | limiting in particular about the addition amount of a electrically conductive agent, Preferably it is 0.1 to 50%. If the addition amount is less than 0.1%, sufficient conductivity is difficult to obtain, and if it exceeds 50%, the mechanical strength is lowered or the appearance is impaired.

  Furthermore, by adding a rubber component as in the present invention, the bending resistance, which is a defect of the amorphous resin, is improved, and a completely new effect that is not found in a belt using a conventional thermoplastic resin is also born. I understood it. For example, when the belt of the present invention is used as an intermediate transfer belt in an electrophotographic apparatus, soft transfer is possible due to the effect of the rubber component to be added, so-called scattered images due to toner scattering can be reduced, There is an advantage that an excellent high quality image can be obtained.

  As described above, according to the present invention, it is possible to newly impart performance that could not be obtained with a conventional endless belt made of a thermoplastic resin.

  Furthermore, for the purpose of imparting other functions, in addition to the material of the present invention, another thermoplastic resin may be added as long as the effects of the present invention are not impaired. In that case, as long as it is in the range which does not affect dimensional stability, you may add regardless of crystallinity and an amorphous property.

  In the endless belt of the present invention, various additives may be further added depending on the purpose. Examples of additives include various fillers (calcium carbonate, talc, mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, wollastonite, diatomaceous earth, glass beads, bentonite, Montmorillonite, asbestos, hollow glass beads, graphite, titanium oxide), reinforcing fibers (glass fiber, carbon fiber, aluminum fiber, stainless steel fiber, brass fiber, metal powder, conductive metal oxide, organometallic compound, organometallic salt) , Fillers, dispersants, neutralizers, plasticizers, flame retardants, crosslinking agents, foaming agents, lubricants (molybdenum disulfide), mold release agents, surface treatment agents, antioxidants, UV absorbers, heat stabilizers, Examples thereof include an antifogging agent, a pigment, a dye, a fluidity modifier, and a hydrolysis inhibitor.

Based on the desired formulation, materials such as acrylic resin, conductive agent, and additive may be premixed and then kneaded and dispersed with a twin screw extruder or the like as a raw material for molding, or each material may be put directly into the molding machine. Molding may be performed.

  Specific examples of the melt molding in the present invention include known melt molding methods such as an extrusion molding method, an extrusion inflation molding method, an extrusion blow molding method, an injection molding method, and an injection blow molding method. Among these, a preferable molding method includes a method using an extrusion molding method or an extrusion inflation molding method. In this method, it is possible to form continuously at a time, which is economically advantageous. Also, it is difficult to form by itself, a material having a low elastic modulus and easily stretched, a material that creeps or is easy to tear, etc. However, it can be molded by combining with a material having good moldability.

  Another preferable molding method is an injection blow method. In this method, a parison is prepared in advance by injection (injection) molding, and this is heated again and blow-molded. Blow molding can be exemplified by simple blow molding or stretch blow molding. This method is advantageous in that although a molding apparatus is expensive, many molded products can be formed in a short time without manpower.

  Below, an example of the manufacturing method of the electrophotographic endless belt used for this invention is demonstrated.

  FIG. 1 shows an example of a schematic configuration of an electrophotographic endless belt molding apparatus (inflation apparatus) according to the present invention. This molding apparatus is mainly composed of an extruder, an extrusion die, and a gas blowing device.

  First, materials such as a molding resin, a conductive agent, and additives are preliminarily mixed based on a desired formulation, and then the molding raw material kneaded and dispersed is put into a hopper 102 provided in the extruder 100.

  In the extruder 100, the set temperature and the screw configuration of the extruder are selected so that the forming raw material has a melt viscosity that enables belt forming in a later process, and the materials are uniformly dispersed.

  The forming raw materials are each melted and kneaded in the extruder 100 to form a melt, and simultaneously enter the two-layer annular die 103. The annular die 103 is provided with a gas introduction path 104. When air is blown into the center of the annular die 103 from the gas introduction path 104, the melt passing through the annular die 103 is expanded in the radial direction in both layers simultaneously. The tubular film 110 is expanded and overlapped in two layers. The gas blown at this time can select nitrogen, a carbon dioxide, argon, etc. other than air.

  The expanded molded body (tubular film) is pulled upward while being cooled by the external cooling ring 105. Usually, in the inflation device, a method is adopted in which the tube is crushed from the left and right by the stabilizing plate 106, folded into a sheet shape, pinched by the pinch roller 107 so that the internal air does not escape, and taken up at a constant speed.

  Next, the taken-up tubular film is cut by the cutting device 108 to obtain a tubular film having a desired size.

  In order to obtain an endless belt having a two-layer structure, a molding machine equipped with two extruders as shown in FIG. 2 may be used.

  Specific examples of the method for removing the creases produced by the extrusion inflation molding method and smoothing the surface include a method of using a pair of cylindrical molds made of materials having different coefficients of thermal expansion and having different diameters. It is done.

  The thermal expansion coefficient of the small-diameter cylindrical mold (inner mold) is larger than the thermal expansion coefficient of the large-diameter cylindrical mold (outer mold), and the inner mold is covered with a cylindrical film formed on the inner mold. Is inserted into the outer mold, and the cylindrical film is sandwiched between the inner mold and the outer mold. The gap between the inner mold and the outer mold is obtained by calculating the difference between the heating temperature and the coefficient of thermal expansion between the inner mold and the outer mold and the required pressure.

  From the inside, the mold set in the order of the inner mold, the cylindrical film, and the outer mold is heated to near the softening point temperature of the resin used for the cylindrical film. Since the inner mold having a large coefficient of thermal expansion tends to expand beyond the inner diameter of the outer mold by heating, a uniform pressure is applied to the entire surface of the cylindrical film. At this time, the surface of the cylindrical film that has reached the vicinity of the softening point is pressed against the inner surface of the outer mold, and the folds can be removed. Thereafter, the cylindrical film can be obtained by cooling and removing the cylindrical film from the mold. According to this method, it is possible to adjust the dimensions and improve the surface properties at the same time. Moreover, a multilayer cylindrical film can be obtained by stacking films to be placed on the inner mold.

  Moreover, the endless belt in the present invention may or may not have a joint. That is, it is good also as a cylindrical film by extruding to a sheet form and rolling up a sheet | seat after that and joining together by ultrasonic welding etc., or using the above inner mold | type-outer mold | types.

The volume resistivity of the endless belt of the present invention is preferably in the range of 1 × 10 ⁵ Ω · cm to 1 × 10 ¹⁶ Ω · cm. The volume resistivity of each layer is preferably set so as to fall within the above range. If it is less than 1 × 10 ⁵ Ω · cm, the resistance is too low, and a sufficient transfer electric field cannot be obtained, and image omission or roughness may occur. If it exceeds 1 × 10 ¹⁶ Ω · cm, it is necessary to increase the transfer voltage, which tends to increase the size of the power source and increase the cost.

  The thickness of the endless belt of the present invention is preferably 40 μm or more and 500 μm or less as a whole. If it is less than 40 μm, the strength is insufficient, the film tends to be stretched, and the withstand voltage is also insufficient. If it exceeds 500 μm, flexible bending becomes difficult, the roller that stretches the belt cannot be followed, and accurate driving cannot be obtained.

  The circumference of the endless belt of the present invention is in the range of 200 to 1000 mm. If it is less than 200 mm, the size of the paper is limited, and if it is 1000 mm or more, the size of the apparatus is increased, which is not preferable.

  The above-described volume resistivity, thickness, and circumference are merely examples, and the range is not particularly limited.

  When the endless belt of the present invention is actually mounted and used in an image forming apparatus, a member for preventing meandering and a position detecting member for detecting the position of the endless belt may be provided as necessary. .

  Hereinafter, an electrophotographic apparatus using the endless belt of the present invention as a transfer conveyance belt will be described in detail. FIG. 3 shows a schematic diagram of an example of an image forming apparatus using an endless belt as a transfer conveyance belt.

  The image forming apparatus shown in FIG. 3 forms toner images of different colors on a plurality of photoconductors as one type of color image forming apparatus using a color separation image superposition transfer system. A toner image on each photoconductor is transferred to obtain a full-color image by aligning the position with one transfer material conveyed in contact with each other.

  The image forming apparatus shown in FIG. 3 has four image forming units I, II, III, and IV arranged in parallel as an electrophotographic process means in the upper part of the apparatus main body 320, and the image forming units I to IV are arranged in parallel. , Photosensitive drums 301Y, 301M, 301C, 301BK as image carriers, primary charging rollers 302Y, 302M, 302C, 302BK as primary chargers, exposure units 303Y, 303M, 303C, 303BK, developing units 304Y, 304M, 304C, 304BK and cleaners 305Y, 305M, 305C, and 305BK are included. The developing devices 304Y, 304M, 304C, and 304BK contain yellow (Y), magenta (M), cyan (C), and black (BK) toners, respectively.

  A transfer device 310 is provided below the image forming units I to IV. The transfer device 310 is an endless transfer stretched between the drive roller 311, the driven roller 312 and the tension roller 313. The image forming apparatus includes a conveyance belt 314 and a transfer charger 315 disposed to face the photosensitive drums 301Y, 301M, 301C, and 301BK of the image forming units I to IV.

  On the other hand, at the bottom of the apparatus main body 320, a cassette 306 is provided which is formed by stacking and storing a plurality of transfer materials P as a recording medium. One transfer material P in the cassette 306 is fed by a paper feed roller 307. It is sent out one by one and conveyed to the registration roller 309 through the conveyance guide 308.

  A separation charger 316 and a fixing device 317 are disposed on the downstream side in the conveyance direction of the transfer material P in the apparatus main body 320, and a paper discharge tray 318 is attached outside the apparatus main body 320.

  In each of the image forming units I to IV, the photosensitive drums 301Y, 301M, 301C, and 301BK are rotationally driven at a predetermined speed in the direction of the arrows in the drawing, and these are uniform by the primary charging rollers 302Y, 302M, 302C, and 302BK, respectively. Is charged. When the exposure units 303Y, 303M, 303C, and 303BK perform exposure according to image information on the respective photosensitive drums 301Y, 301M, 301C, and 301BK that have been charged in this way, the photosensitive drums 301Y, 301M, 301C, and 301BK, An electrostatic latent image is formed on 301BK, and each electrostatic latent image is developed by each developer 304Y, 304M, 304C, 304BK, and is visualized as a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image, respectively. It becomes.

  On the other hand, the transfer material P conveyed from the cassette 306 to the registration roller 309 through the conveyance guide 308 as described above is sent out to the transfer device 310 by the registration roller 309 at the same timing, and is transferred to the transfer belt 314 of the transfer device 310. The transfer material P is adsorbed and moved together with the image forming portions I to IV, and in the process, the transfer charger P 315 causes a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image. Are transferred in layers.

  The transfer material P that has received the transfer of each color toner image as described above is neutralized by the separation charger 316 and separated from the transfer belt 314, and is then conveyed to the fixing device 317 to heat and fix the color toner image. Is finally discharged from the apparatus main body 320 and stacked on the discharge tray 318.

  In the above-described full-color image forming apparatus using the transfer conveyance belt, an example in which the transfer material P is sent in the horizontal direction is shown, but the transfer material P may be sent in the vertical direction or may be sent obliquely.

  The full-color image forming apparatus using the transfer / conveying belt has the advantage that the image output time is fast because a full-color image is formed in one process because each color image is superimposed and transferred while sequentially transferring the transfer paper to each recording apparatus. .

  An electrophotographic apparatus having an intermediate transfer belt using the electrophotographic endless belt of the present invention as an intermediate transfer belt will be specifically described.

  FIG. 4 shows a color image forming apparatus (copier or laser beam printer) using an electrophotographic process and using an endless belt as an intermediate transfer belt.

  Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) that is repeatedly used as a first image bearing member, and is driven to rotate at a predetermined peripheral speed (process speed) in the direction of an arrow.

  The photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by the primary charger 2 during the rotation process. Reference numeral 32 denotes a power source for the primary charger. Here, alternating current is superimposed on direct current, but only direct current may be applied. Next, exposure means (not shown) (color separation / imaging exposure optical system for color original images, scanning exposure system using a laser scanner that outputs a laser beam modulated in accordance with time-series electric digital pixel signals of image information, etc.) When the exposure light 3 is received, an electrostatic latent image corresponding to the first color component image (for example, a yellow color component image) of the target color image is formed.

  Next, the electrostatic latent image is developed with yellow toner Y as the first color by the first developing device (yellow color developing device 41). At this time, the developing devices of the second to fourth developing devices (magenta developing device 42, cyan developing device 43, and black developing device 44) are turned on and do not act on the photosensitive drum 1. The yellow toner image of the first color is not affected by the second to fourth developing devices.

  The intermediate transfer belt 5 is stretched around two rollers, a secondary transfer counter roller 8 and a tension roller 12, and is driven to rotate at the same peripheral speed as the photosensitive drum 1 in the direction of the arrow. The yellow toner image of the first color formed and supported on the photosensitive drum 1 is applied from the primary transfer roller 6 to the intermediate transfer belt 5 in the process of passing through the nip portion between the photosensitive drum 1 and the intermediate transfer belt 5. The primary transfer is sequentially performed on the outer peripheral surface of the intermediate transfer belt 5 by an electric field formed by the primary transfer bias.

  The surface of the photosensitive drum 1 after the transfer of the first color yellow toner image corresponding to the intermediate transfer belt 5 is cleaned by the cleaning device 13.

  Thereafter, similarly, a second color magenta toner image, a third color cyan toner image, and a fourth color black toner image are sequentially superimposed and transferred onto the intermediate transfer belt 5, and a composite color corresponding to a target full color image is obtained. A toner image is formed.

  Reference numeral 7 denotes a secondary transfer roller, which corresponds to the secondary transfer counter roller 8 and is supported in parallel so as to be separated from the lower surface of the intermediate transfer belt 5.

  A primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive drum 1 to the intermediate transfer belt 5 is applied from a bias power source 30 with a polarity (+) opposite to that of the toner. The applied voltage is, for example, in the range of +100 V to 2 kV.

  In the primary transfer process of the first to third color toner images from the photosensitive drum 1 to the intermediate transfer belt 5, the secondary transfer roller 7 can be separated from the intermediate transfer belt 5.

  The composite color toner image transferred onto the intermediate transfer belt 5 is transferred to the transfer material P, which is the second image carrier, with the secondary transfer roller 7 being in contact with the intermediate transfer belt 5 and the paper feed roller. 11, the transfer material P is fed at a predetermined timing to the contact nip between the intermediate transfer belt 5 and the secondary transfer roller 7 through the transfer material guide 10, and the secondary transfer bias is supplied from the power source 31 to the secondary transfer roller. 7 is applied. By this secondary transfer bias, the composite color toner image is secondarily transferred from the intermediate transfer belt 5 to the transfer material P as the second image carrier. The transfer material P that has received the transfer of the toner image is introduced into the fixing device 15 and heated and fixed.

  After the image transfer to the transfer material P is completed, a cleaning charging member 9 disposed so as to be detachable is brought into contact with the intermediate transfer belt 5, and a transfer material having a polarity opposite to that of the photosensitive drum 1 is applied. The transfer residual toner that is not transferred to P but remains on the intermediate transfer belt 5 is given a charge having a polarity opposite to that at the time of primary transfer. Reference numeral 33 denotes a bias power source. Here, alternating current is superimposed on direct current and applied. The transfer residual toner charged to a polarity opposite to that at the time of primary transfer is electrostatically transferred to the photosensitive drum 1 at and near the nip portion with the photosensitive drum 1, thereby cleaning the intermediate transfer member. Since this step can be performed simultaneously with the primary transfer, the throughput is not reduced.

  The electrophotographic endless belt of the present invention has been described mainly with respect to the case where the electrophotographic endless belt is used as a transfer conveyance belt or an intermediate transfer belt, but the electrophotographic endless belt of the present invention includes a photosensitive belt, a transfer belt, The present invention can be applied to all belts used in electrophotographic apparatuses such as a conveyance belt, a fixing belt, a developing belt, a charging belt, and a paper feeding belt.

  The endless belt of the present invention may be mounted on the electrophotographic apparatus main body as it is, or may be used as a belt cartridge that can be attached to and detached from the main body. The endless belt can also be used as a belt for a process cartridge in which an electrophotographic process member such as a latent image carrier or a charging member is integrated.

  Hereinafter, the present invention will be described in more detail with specific examples. In the examples, “part” means part by mass.

(Example 1)
Acrylic resin 41 parts Acrylic rubber particles (average particle size 0.5 μm) 41 parts Carbon black 18 parts The above compound was melt-kneaded at 250 ° C. using a twin screw extruder, extruded with a strand having a diameter of about 2 mm, and cut. It was set as a pellet. Subsequently, using the extruder of FIG. 1, the material was put into a hopper of the extruder and extruded with an annular die to obtain a cylindrical film.

  The cylindrical film was subjected to size adjustment, surface smoothness adjustment, and crease removal using a set of cylindrical bodies made of metals having different coefficients of thermal expansion. The cylindrical film 1 having a high thermal expansion coefficient (inner mold) was covered with the cylindrical film 1, and the cylindrical film 1 was inserted into a cylindrical body (outer mold) having a smooth inner surface and heated at 200 ° C. for 20 minutes. After cooling to room temperature, the tubular film was removed from the inner and outer molds to obtain a tubular film that had been adjusted in size, adjusted in surface smoothness, and had creases removed.

  Both ends of this tubular film were further precisely cut to obtain an endless belt having a peripheral length of 480 mm and a width of 250 mm.

  The obtained belt was mounted on the electrophotographic apparatus shown in FIG. 3 as a transfer / conveying belt, and an endurance test was conducted on 50,000 full-color images. When the belt after the durability test was observed, abnormalities such as cracks, cracks and tears were not observed, and it was found that the belt had sufficient durability.

(Example 2)
Acrylic resin 41 parts Butadiene rubber particles (average particle size 0.5 μm) 41 parts Polyetheresteramide resin 10 parts Carbon black 8 parts The above butadiene rubber particles have a core-shell structure in which the outside of butadiene rubber is covered with acrylic resin It is.

  An endless belt was obtained in the same manner as in Example 1 with the above formulation. The obtained belt was attached to the electrophotographic apparatus of FIG. 4 as an intermediate transfer belt, and a durability test of 50,000 full-color images was performed. When the belt after the durability test was observed, abnormalities such as cracks, cracks and tears were not observed, and it was found that the belt had sufficient durability.

  Also, when this belt is used as an intermediate transfer belt, it has excellent durability, almost no toner scattering, and very clear and high quality with no image defects such as missing characters and uneven color. Images were obtained.

(Example 3)
Acrylic resin 67 parts Acrylic rubber particles (average particle diameter 2 μm) 15 parts Carbon black 18 parts The above formulation was made in the same manner as in Example 1 to obtain an endless belt. The obtained endless belt was mounted on the electrophotographic apparatus shown in FIG. 3 as a transfer / conveying belt, and a durability test was conducted on 50,000 full-color images. When the belt after the durability test was observed, abnormalities such as cracks, cracks and tears were not observed, and it was found that the belt had sufficient durability.

(Example 4)
Acrylic resin 41 parts Butadiene rubber particles (average particle size 5 μm) 41 parts Polyetheresteramide resin 10 parts Carbon black 8 parts The above blending was carried out in the same manner as in Example 1 to obtain an endless belt. The obtained endless belt was mounted on the electrophotographic apparatus shown in FIG. 3 as a transfer / conveying belt, and a durability test was conducted on 50,000 full-color images. When the belt after the durability test was observed, abnormalities such as cracks, cracks and tears were not observed, and it was found that the belt had sufficient durability.

(Example 5)
Acrylic resin 25 parts Acrylic rubber particles (average particle size 0.3 μm) 57 parts Carbon black 18 parts The acrylic rubber particles have a core-shell structure in which the outside of the acrylic rubber is covered with an acrylic resin.

  With the above formulation, an endless belt was obtained in the same manner as in Example 1. The obtained endless belt was attached as an intermediate transfer belt to the electrophotographic apparatus shown in FIG. 4 and subjected to a durability test on 50,000 full-color images. When the belt after the durability test was observed, abnormalities such as cracks, cracks and tears were not observed, and it was found that the belt had sufficient durability.

  Also, when this belt is used as an intermediate transfer belt, it has excellent durability, almost no toner scattering, and very clear and high quality with no image defects such as missing characters and uneven color. Images were obtained.

(Comparative Example 1)
Acrylic resin 82 parts Carbon black 18 parts The above formulation was made in the same manner as in Example 1 to obtain an endless belt.

  The obtained belt was mounted on the electrophotographic apparatus shown in FIG. 3 as a transfer / conveying belt, and a durability test of a full-color image was performed. When about 4000 sheets were printed for the first time in the durability test, a crack was found at the end of the belt, but since it was out of the printing area, the durability continued after that, but it was estimated that the crack continued to grow gradually. When about 4500 sheets were printed, the belt broke and was not durable.

(Comparative Example 2)
Polyethylene terephthalate resin 82 parts Carbon black 18 parts An endless belt was obtained in the same manner as in Example 1 with the above formulation.

  The obtained belt was mounted on the electrophotographic apparatus shown in FIG. 3 as a transfer / conveying belt, and a durability test of a full-color image was performed.

  There was no problem at the beginning of the endurance test, but during the endurance test, the temperature of the endless belt itself rose due to the effect of temperature rise in the machine, etc., which caused crystallization to progress and the circumference to change (shrink). The tension on the belt became too large, resulting in torque over and unusable.

It is a figure which shows an example of schematic structure of the shaping | molding apparatus of the endless belt (single layer) of this invention. It is a figure which shows an example of schematic structure of the shaping | molding apparatus of the endless belt (2 layers) of this invention. It is a figure which shows an example of schematic structure of the full-color electrophotographic apparatus provided with the endless belt of this invention. It is a figure which shows an example of schematic structure of another full-color electrophotographic apparatus provided with the endless belt of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Primary charger 3 Exposure light 5 Intermediate transfer belt 6 Primary transfer roller 7 Secondary transfer roller 8 Secondary transfer counter roller 9 Cleaning charging member 10 Transfer material guide 11 Paper feed roller 12 Tension roller 13 Photosensitive drum cleaning Device 15 Fixing device 30 Bias power source 31 Bias power source 32 Primary charger power source 33 Bias power source 41 Yellow color developing device 42 Magenta color developing device 43 Cyan color developing device 44 Black color developing device 100 Single screw extruder 101 Single screw extruder 102 Hopper 103 annular die 104 gas introduction path 105 external cooling ring 106 stabilizer plate 107 pinch roller 108 cutting device 110 cylindrical films 301Y, 301M, 301C, 301BK photosensitive drums 302Y, 302M, 302C, 3 02BK Primary charging rollers 303Y, 303M, 303C, 303BK Exposure units 304Y, 304M, 304C, 304BK Developers 305Y, 305M, 305C, 305BK Cleaner 306 Paper feed cassette 307 Paper feed roller 308 Transport guide 309 Registration roller 310 Transfer device 311 Drive roller 312 Driven roller 313 Tension roller 314 Transfer conveyor belt 315 Transfer charger 316 Separation charger 317 Fixing device 318 Paper discharge tray 320 Image forming apparatus main body P Transfer material

Claims (15)

In an acrylic resin, and rubber particles, and the conductive filler is a electrophotographic endless belt device having a layer comprising a resin composition dispersed, conductive fillers, localized in the acrylic resin side An endless belt for an electrophotographic apparatus . The endless belt for an electrophotographic apparatus according to claim 1, wherein the rubber particles have a particle diameter of 0.05 μm to 10 μm. The endless belt for an electrophotographic apparatus according to claim 1 or 2, wherein a mixing ratio of the acrylic resin and the rubber particles is 30:70 to 95: 5 by mass ratio. The endless belt for an electrophotographic apparatus according to claim 1, wherein the rubber particles have a multilayer structure. The endless belt for an electrophotographic apparatus according to claim 1, wherein the rubber particles are mainly composed of acrylic rubber. The endless belt for an electrophotographic apparatus according to claim 1, wherein the conductive filler is an electroconductive filler. The endless belt for an electrophotographic apparatus according to claim 6 , wherein the electroconductive filler is carbon black. It said resin composition further polyetherester, polyetheramide, or an electrophotographic apparatus for endless belt according to any one of claims 1 to 7 containing polyetheresteramide. The endless belt for an electrophotographic apparatus according to any one of claims 1 to 8 , wherein the endless belt is a transfer conveyance belt or an intermediate transfer belt. Said resin composition, rubber particles and electrophotographic apparatus for endless belt according to any one of claims 1 to 9 is obtained and a conductive filler each addition of the acrylic resin. A process for producing an endless belt for an electrophotographic apparatus, comprising a step of melt-molding a resin composition obtained by adding rubber particles and a conductive filler to an acrylic resin to form a cylindrical film. The method for producing an endless belt for an electrophotographic apparatus according to claim 11, wherein the step includes a step of performing blow molding of the resin composition or a step of performing blow molding. Belt cartridge, characterized by comprising one of the electrophotographic endless belt according to claim 1-10. The process cartridge characterized by comprising any one of the endless belt for an electrophotographic apparatus according to claim 1-10. An image forming apparatus comprising the endless belt for an electrophotographic apparatus according to claim 1 .

Images