JP4136507B2 - Electrophotographic belt, image forming apparatus, and process cartridge - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an electrophotographic belt, an image forming apparatus, and a process cartridge, and more particularly, to a copying machine or a printer using an electrophotographic system.Used as an intermediate transfer belt or transfer conveyance belt of an image forming apparatusThe present invention relates to an electrophotographic belt, an image forming apparatus including the electrophotographic belt, and a process cartridge.
[0002]
[Prior art]
  An image forming apparatus using an electrophotographic belt such as an intermediate transfer belt or transfer / conveying belt sequentially stacks and transfers multiple component color images of full-color image information and multi-color image information to synthesize and reproduce full-color images and multi-color images. The present invention is effective as a full-color image forming apparatus or a multicolor image forming apparatus that outputs the image formed product, or an image forming apparatus having a full-color image forming function or a multicolor image forming function. Even a monochrome image forming apparatus is effective as means for improving the printing speed.
[0003]
  For example, a full-color image forming apparatus having an image forming apparatus using an intermediate transfer belt or the like is an image in which a transfer material is pasted or adsorbed on a transfer drum, which is a conventional technique, and an image is transferred from the electrophotographic photosensitive member thereto. Compared with a full-color image forming apparatus having a forming apparatus, for example, a transfer apparatus described in JP-A-63-301960, the transfer material is processed (for example, gripped by a gripper, adsorbed, given a curvature, etc.) Images can be transferred from the intermediate transfer belt without the need for a thin sheet of paper (40 g / m) such as envelopes, postcards, and label papers.²Paper) to thick paper (200g / m²Paper), it has an advantage that a wide variety of transfer materials can be selected regardless of the width and width.
[0004]
  Furthermore, a method of arranging a plurality of electrophotographic photosensitive members corresponding to the number of colors and superimposing colors by continuously transferring images of each color in one pass on an intermediate transfer belt or a transfer material supported by a transfer conveyance belt. It is effective as a means for greatly improving the printing speed. Even in the case of a monochrome image forming apparatus, a transfer / conveying belt may be used to improve the printing speed and at the same time obtain an excellent image quality. The transfer / conveying belt can adsorb and support the transfer material in advance and stably feed it to the image transfer portion at a high speed, and also has an effect of preventing the transfer material from being wound around the electrophotographic photosensitive member. .
[0005]
  When used as an intermediate transfer belt, the degree of freedom in arranging inside an image forming apparatus is increased compared to the case of using a rigid cylinder such as an intermediate transfer drum, and the apparatus body can be made smaller by effectively using space. And cost reduction.
[0006]
  However, these electrophotographic belts must satisfy various characteristics depending on the purpose of use, and there are many problems to be solved. In particular, in recent years, in order to improve image quality, the exposure spot diameter and toner particle diameter have been made finer in image forming apparatus bodies such as LBPs (laser beam printers) and copying machines, and development and transfer electric field control have been made more precise. Various means are adopted. As a result, very high-definition images can be obtained, but on the other hand, cost reduction is also an important issue, such as a method for reducing the number of parts and waiting for many functions in one part, etc. As much as possible, miniaturization and weight reduction of the device are being promoted. In addition, as the price of the main unit declines, the purchase range expands, and a design that is expected to be used in a wide range of environments with low temperature and low humidity or high temperature and high humidity compared to conventional cases such as small offices and general households has come to be required. It is coming. As a result, it is more important than ever for electrophotographic belts such as intermediate transfer belts and transfer conveyance belts to improve image quality, reduce costs, handle a wide range of environments, and optimize the design to match the configuration of the main body of the image forming apparatus. It can be said that
[0007]
  The electrophotographic belt uses a means of mixing some resistance control substance to adjust the resistance, but when considering uniform resistance, conductive fillers such as carbon black and conductive metal oxide particles are used. Hard to do. These are likely to cause uneven resistance due to particle agglomeration and non-uniform dispersion. Particularly, a very low resistance particle agglomerate has a large influence on the transfer electric field at the site even when the size is about 50 μm. If the size of the aggregate is several times to ten times or more, color loss may occur in the form of spots. In the worst case, since there are problems such as loss due to dielectric breakdown and ignition, it is necessary to reduce the amount of conductive filler used and to improve the dispersion means.
[0008]
  As a material for solving this problem, a means of adding a low molecular weight so-called ionic conductive agent such as various inorganic salts and surfactants, a high molecular weight antistatic resin, or the like is effective. Since these materials are less likely to agglomerate than conductive fillers, the resistance unevenness and dielectric breakdown of the electrophotographic belt are greatly improved. However, there is a very difficult problem in the uniformity of the resistance. For example, when a belt in which a low molecular weight ionic conductive agent is dispersed and resistance uniformity is sufficiently increased is used as an intermediate transfer belt, an image problem due to a discharge phenomenon may occur. This phenomenon occurs when a solid or halftone image is printed in a low-temperature, low-humidity environment, causing a peeling discharge in the primary transfer section or secondary transfer section, disturbing the toner image, and causing a polka dot transfer failure. is there. On the other hand, in a high temperature and high humidity environment, streaky density unevenness may occur in parallel with the electrophotographic photosensitive member. In high-temperature and high-humidity environments, the resistance of each part decreases and the discharge phenomenon decreases, but the charge amount of the toner also decreases.Therefore, even if the primary transfer part is very weak, primary transfer occurs when peeling discharge occurs. It is considered that the variation in the charged amount of the toner is promoted, the secondary transfer efficiency is partially changed, and striped image unevenness occurs.
[0009]
  On the other hand, when an electrophotographic belt whose resistance is adjusted with a high molecular weight material such as an antistatic resin is used as an intermediate transfer belt or a transfer conveyance belt, an electrophotographic belt is formed into a halftone image in a high temperature and high humidity environment. In some cases, density unevenness due to resistance unevenness may occur. This phenomenon is thought to be due to the fact that the image density changes due to local fluctuations in transfer efficiency or retransfers that occur as the resistance of the electrophotographic belt changes.
[0010]
  There are several possible reasons for this phenomenon to occur, but it is thought that when a low molecular weight ionic conductive agent is used and the resistance is made uniform, the performance of suppressing the peeling discharge phenomenon becomes insufficient. . In order to suppress the discharge phenomenon, a point for releasing the charge on the belt surface is necessary, and it is considered effective that the portions where the resistance is somewhat lower than the surroundings are evenly dispersed. An electrophotographic belt using an ionic conductive agent having a low molecular weight is likely to cause a discharge phenomenon because there are few points for releasing such charges because the resistance is uniform.
[0011]
  However, since the aggregate of the conductive filler causes another problem as described above, it is necessary that the point of releasing the electric charge is a very small size within several μm to 50 μm and the resistance value is not too low.
[0012]
  Therefore, a means for mixing a high-molecular-weight resistance adjusting material such as an antistatic resin under appropriate conditions is effective as a means for reducing the discharge phenomenon. The antistatic resin is usually incompatible with the main binder resin, and is present in the form of islands of several μm to several tens of μm in the electrophotographic belt. This part is considered to act as a point for releasing electric charge. The volume resistivity of the antistatic resin is generally 3 to 6 digits higher than that of a conductive filler such as carbon black, and generally 2 to 5 digits lower than the overall resistance of the electrophotographic belt. Therefore, it is difficult to cause dielectric breakdown or transfer loss due to concentration of the transfer electric field at a very low resistance, but the resistance is low enough to release charges, and the conflicting problem of suppression of discharge phenomenon and dielectric breakdown It can be said that this is a suitable material for solving the problem. However, on the other hand, it is incompatible with the thermoplastic resin, so that it tends to give up to a low molecular weight ionic conductive agent in terms of dispersibility, and although it is slightly, resistance unevenness is likely to occur.
[0013]
  This uneven resistance is generally much less than that of an electrophotographic belt in which a conductive filler such as carbon black is dispersed, and has not been a problem in the past. However, depending on the configuration of the image forming apparatus main body as described above, Density unevenness may occur in a halftone image.
[0014]
  Accordingly, when the addition amount of the antistatic resin is increased, the image density unevenness is worsened, and when it is decreased, polka dots and striped unevenness are generated due to the discharge phenomenon.
[0015]
  As a countermeasure, when a low molecular weight ionic conductive agent and an antistatic resin are used in combination, although there is a certain improvement effect, a complete problem has not yet been solved.
[0016]
  The reason why the resistance adjustment of the electrophotographic belt has become more complex is not certain, but for example, the separation charger and pre-secondary transfer charger are omitted to reduce the cost of the device, the number of power supply devices is reduced, etc. It is considered that the main body side design makes it difficult to suppress a fine discharge phenomenon that occurs on the surface of the electrophotographic belt or to impart a uniform charge amount to the toner. There is an increasing number of non-magnetic one-component methods that can be made smaller than two-component development methods, but this method may be inferior to two-component development using a carrier in terms of giving a uniform and high charge amount to the toner. The possibility of a decrease in the toner charge amount in a high temperature and high humidity environment cannot be denied. In addition, it is estimated that the nonuniformity of the transfer, which has been inconspicuous in the past, has become apparent as a result of the progress of uniformization of the developed image as another factor. In addition to these, the expansion of the use environment further increases the discharge phenomenon and density unevenness, making it more difficult to design an electrophotographic belt.
[0017]
  Therefore, it is not easy to adjust the resistance value of the electrophotographic belt because such problems occur, but the electrophotographic image can be changed by changing the amount of addition of an antistatic resin or a low molecular weight ionic conductive agent, which is a conventional technique. This indicates that the problem cannot be solved even if the resistance of the belt is combined. Electrophotographic belts need to be optimally designed from both a microscopic and macroscopic viewpoint, taking into account not only single-sided properties such as resistance values, but also the main body configuration and usage environment. It can be said that.
[0018]
  On the other hand, it is difficult to obtain the same life as the printer or copier body for electrophotographic belts and electrophotographic photosensitive members such as intermediate transfer belts and transfer conveyance belts. There is also a problem that is complicated. There is a method of using a cartridge in which an electrophotographic photosensitive member, an intermediate transfer belt, and a transfer conveyance belt are integrated as a means for greatly reducing the labor of the replacement.
[0019]
  However, if the electrophotographic photosensitive member and the intermediate transfer belt are integrated into one cartridge, a problem different from the case where the intermediate transfer belt is set on the main body when the main body is installed is likely to occur. In many cases, the intermediate transfer belt and the electrophotographic photosensitive member are left in various environments for a long time in an integrated state. For example, a so-called bleed that the component added to the intermediate transfer belt oozes out to the surface and adheres to the electrophotographic photosensitive member may lower the charging potential or affect the movement of charges, causing streaks at the contact portion. An image abnormality occurs. The most serious problem is when the photosensitive layer is cracked by the material transferred from the intermediate transfer belt. Such cracking of the photosensitive layer is conspicuous in the thickest layer among the photosensitive layers, and is easily generated in the charge transport layer in the case of a laminated electrophotographic photoreceptor.
[0020]
  Such a phenomenon has been found to be promoted particularly in a high temperature environment, and the humidity tends to be adversely affected as the humidity increases. Therefore, the intermediate transfer belt electrophotographic photosensitive member integrated cartridge or the like needs to be designed in consideration of the influence of temperature and humidity received in the distribution stage.
[0021]
  Further, the cleaning mechanism for the toner remaining on the intermediate transfer belt applies a charge opposite to that of the primary transfer to the transfer residual toner by the charging device, and returns to the electrophotographic photosensitive member simultaneously with the primary transfer to clean the electrophotographic photosensitive member. A method of collecting by a mechanism is preferable (primary transfer simultaneous cleaning). According to this means, there is no need to reduce the number of waste toner boxes or to create a waste toner transport mechanism as compared with the case where a cleaning device such as a fur brush or blade is provided on the intermediate transfer belt to perform cleaning separately from the electrophotographic photosensitive member. This is preferable from the viewpoints of downsizing and cost reduction of the apparatus main body. Since there is no need to replace a plurality of waste toner boxes, the maintainability is also improved. However, if the transfer residual toner on the intermediate transfer belt is not given a uniform and appropriate charge, it will cause poor cleaning and interference with the primary transfer toner, resulting in an image problem. Therefore, the intermediate transfer belt and the conductive roller or corona charger It is necessary for a uniform current to flow between the charging mechanisms for cleaning.
[0022]
  Accordingly, the uniformity of the resistance and discharge phenomenon of the intermediate transfer belt is an essential element for performing the primary transfer simultaneous cleaning.
[0023]
[Problems to be solved by the invention]
  As described above, an image forming apparatus that completely solves various problems in an image forming apparatus using an electrophotographic belt has not yet been obtained.
[0024]
  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic belt, an image forming apparatus, and a process cartridge capable of obtaining a high image quality without image omission and density unevenness, and obtaining a good image even when the environment fluctuates for a long period of transportation or in a short period of time. Is to provide.
[0025]
[Means for Solving the Problems]
  An image forming apparatus for transferring a toner image obtained by visualizing an electrostatic latent image formed on an electrophotographic photosensitive member with toner according to the present invention onto a transfer material by electrostatic means.As an intermediate transfer belt or transfer conveyor beltIn the electrophotographic belt used,
  The electrophotographic belt contains at least polyvinylidene fluoride, polyetheresteramide, and polyolefin polyether;
  The maximum current value measured by the following current value measurement method is in the range of 1.18 times to 1.28 times the minimum current value.
An electrophotographic belt is provided that is characterized by:
  <Current value measurement method>
  (I) An electrophotographic belt for measuring resistance is stretched with a tension of 19.6 N (2 kgf) using two rollers including a driving roller. An ammeter is connected to a roller that is not the driving roller of the two rollers. The electrophotographic belt stretched between a roller that is not a driving roller and a conductive rubber roller among the two rollers is sandwiched,
  (Ii) Next, a voltage is applied from the conductive rubber roller while rotating the stretched electrophotographic belt with the driving roller at a peripheral speed of 120 mm / sec, and the current value is measured with the ammeter. And the recorder continuously records the current value for one round of the electrophotographic belt.
  (Iii) Next, among the continuously recorded current values, how many times the maximum current value is the minimum current value is obtained.
[0026]
  According to the present invention, an electrophotographic photoreceptor,
Charging means and exposure means for forming an electrostatic latent image on the electrophotographic photosensitive member;
Developing means for visualizing the electrostatic latent image with toner to obtain a toner image;
An intermediate transfer belt having a contact portion with the electrophotographic photosensitive member;
Primary transfer means for primary transfer of the toner image from the electrophotographic photosensitive member to the intermediate transfer belt at the contact portion;
Secondary transfer means for secondary transfer of the toner image on the intermediate transfer belt to a transfer material;
In an electrophotographic belt used as the intermediate transfer belt of an image forming apparatus having
  The electrophotographic belt is at leastPolyvinylidene fluorideWhenPolyether ester amides and polyolefin polyethersAnd containing
  Measured by the following current value measurement methodMaximum current value is maximumsmall1. Current value18Double1.28Double the range
An electrophotographic belt is provided.:
  <Current value measurement method>
  (I) An electrophotographic belt for measuring resistance is stretched with a tension of 19.6 N (2 kgf) using two rollers including a driving roller. An ammeter is connected to a roller that is not the driving roller of the two rollers. The electrophotographic belt stretched between a roller that is not a driving roller and a conductive rubber roller among the two rollers is sandwiched,
  (Ii) Next, a voltage is applied from the conductive rubber roller while rotating the stretched electrophotographic belt with the driving roller at a peripheral speed of 120 mm / sec, and the current value is measured with the ammeter. And the recorder continuously records the current value for one round of the electrophotographic belt.
  (Iii) Next, among the continuously recorded current values, how many times the maximum current value is the minimum current value is obtained..
[0027]
  According to the present invention, an electrophotographic photoreceptor,
Charging means and exposure means for forming an electrostatic latent image on the electrophotographic photosensitive member;
Developing means for visualizing the electrostatic latent image with toner to obtain a toner image;
An intermediate transfer belt having a contact portion with the electrophotographic photosensitive member;
Primary transfer means for primary transfer of the toner image from the electrophotographic photosensitive member to the intermediate transfer belt at the contact portion;
Secondary transfer means for secondary transfer of the toner image on the intermediate transfer belt to a transfer material;
In an image forming apparatus having
  The intermediate transfer beltElectrophotographic beltIs
An image forming apparatus is provided.
[0028]
  Further, according to the present invention, there is provided a process cartridge configured to be detachable from the main body of the image forming apparatus, wherein the process cartridge is supported integrally with the electrophotographic photosensitive member and the intermediate transfer belt. The
[0029]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described in detail.
[0030]
  In the present invention, an antistatic resin excellent in resistance uniformity is avoided as much as possible by avoiding the use of a resistance control agent that easily causes aggregation and bias at the particle level such as conductive fillers such as carbon black, conductive metal oxide and metal powder. Is selected. Furthermore, in order to obtain an electrophotographic belt that can prevent image density unevenness and polka dot images due to the above slight discharge phenomenon and resistance unevenness as described above, the dispersion state of the antistatic resin is optimally maintained and is microscopic. However, it is necessary to maintain the resistance uniformity at a high level on a macro scale while securing a fine discharge point by the sea-island structure of the resin. In order to achieve this, in the present invention, the main binderPolyvinylidene fluorideAntistatic resin incompatible withAs polyetheresteramide and polyolefin polyetherIt is characterized in that two types are used. When different types of antistatic resins are used, it is considered that the antistatic resins do not form a large lump because the antistatic resins have different polarities and melt viscosities, and form a moderately fine island structure. As a result, the discharge phenomenon can be suppressed without deteriorating resistance unevenness.
[0031]
  However, if these materials are used, the effect of the present invention is not necessarily obtained, and the difference between the maximum and minimum current values of each part when a voltage is applied to the electrophotographic belt is 1.02 to 3.0. It is essential to select the manufacturing means and manufacturing conditions so thatIn the present invention, it is 1.18 times to 1.28 times.The When the difference between the current values exceeds 3.0 times, the density unevenness of the image is deteriorated, and when the difference is less than 1.02, polka dots or stripe-like unevenness due to the discharge phenomenon may occur.
[0032]
  On this occasion, Polyvinylidene fluorideFor the temperature at which the melt viscosity of 10000 Pa · s becomesPolyolefin polyether has a melt viscosity of 10,000 Pa · stemperatureLow,To increase the temperature at which the melt viscosity of polyether ester amide reaches 10,000 Pa · sThe effect is higher. The temperature at which the melt viscosity reaches 10,000 Pa · s is the main binderPolyvinylidene fluoridetaller thanPolyetheresteramideThe melt viscosity during melt kneading and moldingPolyvinylidene fluorideIt becomes higher and the change of the shape with respect to the shear during molding is suppressed, and a relatively fine island is formed. On the other hand, the temperature is lowPolyolefin polyetherHas viscosity during kneading and moldingPolyvinylidene fluorideLower and stretched by the share to form a somewhat larger island structure. As a result, antistatic resinPolyether ester amides and polyolefin polyethersIs maintained in an optimal state, and both suppression of discharge and resistance uniformity can be achieved at a high level.
[0033]
  PoThe reolefin polyether has a long non-polar olefin chain and does not contain a polyamide block, so it is difficult to be compatible with the polyether ester amide, and the melt viscosity is also lowered due to the influence of the polyolefin block. It has the preferable characteristics above. These antistatic resinsPolyether ester amides and polyolefin polyethersThe total amount of is preferably in the range of 4 to 35% by mass with respect to the electrophotographic belt. If it is less than 4%, the effect of adding an antistatic resin is difficult to obtain, and if it exceeds 35%, the strength of the electrophotographic belt tends to decrease. Also,Polyether ester amides and polyolefin polyethersThe addition ratio ofPolyether ester amide: Polyolefin polyetherA range of 1: 9 to 9: 1 is preferred, outside this rangePolyether ester amides and polyolefin polyethersTherefore, it becomes difficult to obtain the effect of addition, and the discharge phenomenon and density unevenness are likely to occur.
[0034]
  By adopting the above configuration, the electrophotographic belt of the present invention can solve many problems and exhibit good performance.
[0035]
  An example of the embodiment of the present invention is shown below, but the present invention is not necessarily limited thereto.
[0036]
  The molding method is preferably a production method that can produce a seamless belt, has high production efficiency, and can reduce costs. As a means for this, there is a method of continuously melting and extruding from an annular die, and then cutting to a required length to manufacture a belt.
[0037]
  For example, inflation molding is suitable. Inflation molding not only has high molding efficiency, but also has the advantage that it is possible to extrude a plurality of sizes of tubes with different diameters from one type of die, reducing capital investment when deploying to multiple models. Furthermore, since it is expanded in a molten state at the time of extrusion, there is an advantage that a portion thicker than normal extrusion is selectively stretched in the circumferential direction and thickness unevenness is reduced.
[0038]
  As another manufacturing means, there is a manufacturing method in which a sheet is formed with a T-die, then cut to a desired length, end portions are joined, and a belt is formed. This method has high film thickness uniformity and the ability to use a biaxial stretching device, which can improve the mechanical strength of the film. There are also problems such as coming out.
[0039]
  The thickness of the electrophotographic belt in the present invention is preferably in the range of 40 μm to 300 μm. If it is less than 40 μm, the molding stability is insufficient, thickness unevenness is likely to occur, the durability is insufficient, and the belt may be broken or cracked. On the other hand, when the thickness exceeds 300 μm, the material increases and the cost increases, and the difference in the peripheral speed between the inner surface and the outer surface of the tensioning shaft increases when incorporated in the main body of the image forming apparatus. Problems such as image splattering due to shrinkage are likely to occur. Furthermore, there is a problem that the bending durability is lowered and the rigidity of the belt becomes too high, resulting in an increase in driving torque, leading to an increase in size and cost of the main body.
[0040]
  FIG. 5 shows an example of a molding apparatus according to the present invention. The apparatus basically comprises an extruder, an extrusion die, and a gas blowing device.
[0041]
  First, based on a desired formulation, a molding resin, a conductive agent, an additive, and the like are premixed in advance, 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 subsequent process, and the raw materials are uniformly dispersed. The forming raw material is melted and kneaded in the extruder 100 to become a melt and enters the annular die 103. The annular die 103 is provided with a gas introduction path 104, and when the air is blown into the center of the annular die 103 from the gas introduction path 104, the melt that has passed through the die 103 expands and expands in the radial direction to form a cylindrical shape. Film 110 is obtained.
[0042]
  The gas blown at this time can select nitrogen, a carbon dioxide, argon, etc. other than air. The expanded molded body is pulled upward while being cooled by the external cooling ring 105. Usually, in the inflation apparatus, the tube is crushed from the left and right with the stabilizing plate 106, folded into a sheet shape, pinched by the pinch roller 107 so that the air inside does not escape, and taken at a constant speed. Next, the taken film is cut by the cutting device 108 to obtain a tubular film having a desired size. Next, the cylindrical film is covered with a cylindrical mold made of metal or the like and heated, whereby fine adjustment of dimensions and creases attached to the film can be removed. Thereafter, attachment of a reinforcing member, a rotation guide member, and a position detection member and precision cutting are performed as necessary to manufacture an electrophotographic belt.
[0043]
  Further, the explanation was for a single-layer belt, but in the case of two layers, an additional extruder 101 is additionally arranged as shown in FIG. 6, and an annular die 103 for two layers is formed simultaneously with the kneaded melt of the extruder 100. The two-layer belt can be obtained by feeding the kneaded melt from the extruder 110 to the two layers and expanding them simultaneously.
[0044]
  Of course, when there are three or more layers, an extruder should be prepared corresponding to the number of layers. As described above, according to the present invention, not only a single layer but also a multi-layered electrophotographic belt can be formed in a single step and with high dimensional accuracy in a short time. The fact that this short-time molding is possible sufficiently suggests that mass production and low-cost production are possible.
[0045]
  When inflation molding is performed in the present invention, the former is a comparison of the thickness ratio between the annular die and the formed cylindrical film, that is, the thickness of the cylindrical film with respect to the width of the gap (slit) of the annular die. On the other hand, the latter is preferably 1/3 or less, more preferably 1/5 or less.
[0046]
  Similarly, when the ratio of the diameter of the annular die and the formed cylindrical film is expressed as a percentage of the outer diameter of the tubular film 110 with respect to the outer shape of the die slit of the annular die 103, a range of 50% to 400% is obtained. preferable.
[0047]
  These represent the stretched state of the material, and when the thickness ratio is greater than 1/3, the stretching is insufficient, and problems such as a decrease in strength and unevenness in resistance and thickness may occur. On the other hand, when the outer shape exceeds 400% or less than 50%, it is stretched excessively, so that molding stability is lowered or it is difficult to ensure the thickness necessary for the present invention.
[0048]
  Next, the cylindrical film may be processed using a mold for the purpose of adjusting the surface smoothness and dimensions, or removing a crease attached to the film during molding.
[0049]
  Specifically, there is a method of using a set of cylindrical shapes having different diameters made of materials having different linear expansion coefficients. The material is selected so that the linear expansion coefficient of the small-diameter cylindrical (inner mold) is larger than that of the large-diameter cylindrical (outer mold). As an example, the inner shape is made of aluminum, and the outer shape is made of stainless steel. After covering the inner mold with the cylindrical film, the inner mold is inserted into the outer mold, and the cylindrical film is sandwiched between the inner mold and the outer mold. At this time, it is preferable that the inner mold is designed to be slightly larger than the cylindrical film and the film is covered while being stretched. The gap between the molds is obtained by calculating the difference between the heating temperature and the linear expansion coefficient between the inner and outer molds and the required pressure. 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. By heating, the inner mold having a large linear expansion coefficient expands from the outer mold, and a uniform pressure is applied to the entire surface of the cylindrical film. At this time, the outer circle of the resin film that has reached the vicinity of the softening point is pressed against the inner surface of the outer mold that has been processed smoothly, and the smoothness of the resin film surface is improved. Then, smooth surface properties can be obtained by cooling and removing the film from the mold.
[0050]
  Moreover, the removal of a crease | fold and fine adjustment of a dimension can be performed also by the method of covering and heating the film shape | molded using only said inner type | mold.
[0051]
  Thereafter, if necessary, the reinforcing member, the guide member, and the position detecting member are attached or precision cut to manufacture an electrophotographic belt.
[0052]
  The main material among the molding raw materials used for the belt of the present inventionIsThermoplastic resinIsPolyvinylidene fluorideInThe
[0053]
  Next, an antistatic resin is added to adjust the electric resistance value of the electrophotographic belt of the present invention.TheAs antistatic resinTheReether ester aminoAndThe combination of polyolefin polyetherUsed. Since these materials have a high molecular weight, they also have the advantage of being less likely to cause bleeding.
[0054]
  Furthermore, other conductive materials such as various metal salts, glycols, and surfactants may be added within a range that does not affect the characteristics of the present invention. But become the mainPolyvinylidene fluorideIt is preferable to select a material that is sufficiently compatible with each other and does not cause bleeding.
[0055]
  In addition, when it is necessary to improve or color the electrophotographic belt, such as non-conductive metal oxide particles or various pigments, other materials may be added. For example, when a fine powder such as a metal oxide having a particle size of 1 μm or less is added as a reinforcing material, the tensile elastic modulus and tensile strength of the electrophotographic belt are increased, and there are effects such as reduction in durability and color misregistration. In this case, it is necessary to prevent the particles from aggregating as much as possible. However, unlike the conductive filler, it is non-conductive, so if it is an aggregate of about several tens of μm, it may affect the image or cause dielectric breakdown. There is nothing. As a measure of non-conductivity, it can be used without any problem as long as the powder resistance is higher than that of an electrophotographic belt. Examples of these powders include silicon dioxide, titanium dioxide, zinc oxide, calcium carbonate, and aluminum oxide.
[0056]
  As a means for dispersing the material, a normal method can be used. However, since a high shear force (shear) can be obtained, the twin screw extruder is suitable for uniform dispersion of the material.
[0057]
  Next, an example of an image forming apparatus using the belt of the present invention is shown.
[0058]
  FIG. 1 shows a full-color image forming apparatus (copier or laser beam printer) using an electrophotographic process.
[0059]
  A rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 1 that is repeatedly used as a first image bearing member is driven to rotate at a predetermined peripheral speed (process speed) in the direction of an arrow.
[0060]
  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, by exposure means (not shown) (color separation / imaging exposure optical system for full-color original image, 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.) By receiving the exposure light 3, an electrostatic latent image corresponding to a first color component image (for example, a yellow color component image) of the target full-color image is formed.
[0061]
  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 units of the second to fourth developing units (magenta color developing unit 42, cyan color developing unit 43, and black color developing unit 44) are turned off and do not act on the photosensitive drum 1. The first color yellow toner image is not affected by the second to fourth developing units.
[0062]
  The intermediate transfer belt 5 is rotationally driven at the same peripheral speed as the photosensitive drum 1 in the direction of the arrow.
[0063]
  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.
[0064]
  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.
[0065]
  In the same manner, the second color magenta toner image, the third color cyan toner image, and the fourth color black toner image are sequentially superimposed and transferred onto the intermediate transfer belt 5 and synthesized corresponding to the target full color image. A color toner image is formed.
[0066]
  The secondary transfer roller 7 is supported in parallel with the secondary transfer counter roller 8 and is arranged in a state in which it can be separated from the lower surface of the intermediate transfer belt 5.
[0067]
  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.
[0068]
  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.
[0069]
  When the composite color toner image transferred onto the intermediate transfer belt 5 is transferred to the transfer material P, the secondary transfer roller 7 is brought into contact with the intermediate transfer belt 5 and passes through the transfer material guide 10 from the paper feed roller 11. Thus, the transfer material P is fed to the contact nip between the intermediate transfer belt 5 and the secondary transfer roller 7 at a predetermined timing, and the secondary transfer bias is applied from the power source 31 to the secondary transfer roller 7. 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. At this time, an apparatus for assisting charging of the toner image before the secondary transfer on the intermediate transfer belt is not added to the apparatus. The transfer material P that has received the transfer of the toner image is introduced into the fixing device 15 and heated and fixed.
[0070]
  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 does not decrease.
[0071]
  Next, a process cartridge in which the intermediate transfer belt and the electrophotographic photosensitive member are integrally supported will be described with reference to FIG. The cartridge of the present invention only needs to be configured so that at least the intermediate transfer belt 5, the electrophotographic photosensitive member 1, and the primary transfer means 6 are integrally supported and are detachable from the apparatus main body. In FIG. 2, an intermediate transfer belt cleaning mechanism 13 and an electrophotographic photosensitive member cleaning mechanism 9 are also attached as an integrated unit. As described above, the cleaning of the intermediate transfer belt of the present invention is a mechanism necessary for charging the transfer residual toner to a polarity opposite to that of the primary transfer and returning it to the electrophotographic photosensitive member at the primary transfer portion. It is equipped with a cleaning roller 9 made of a resilient elastic body. Cleaning of the electrophotographic photosensitive member is blade cleaning. This cartridge also includes a waste toner container (not shown), and the transfer residual toner on both the intermediate transfer belt and the electrophotographic photosensitive member is also discarded at the same time when the cartridge is replaced, which contributes to improvement in maintainability. .
[0072]
  Further, the intermediate transfer belt is stretched by two rollers of a driving roller 8 and a tension roller 12 to reduce the number of parts and reduce the size. Here, the driving roller 8 is simultaneously a counter roller of the cleaning roller. The tension roller 12 that rotates following the intermediate transfer belt has a sliding mechanism, is pressed in the direction of the arrow by a compression spring, and applies tension to the intermediate transfer belt. The slide width is about 1 to 5 mm, and the total pressure of the spring is about 5 to 100N. Further, the electrophotographic photosensitive member 1 and the driving roller 8 have a coupling (not shown), and a rotational driving force is transmitted from the main body.
[0073]
  Further, another example of the image forming apparatus is shown in FIGS. 3 and 4 are provided with the same number of developers as the number of developers necessary for image formation, and there is an advantage that the printing speed of full-color printing is remarkably improved.
[0074]
  FIG. 3 uses an intermediate transfer belt. As in FIG. 1, the visible image formed on the electrophotographic photosensitive member 1 is sequentially transferred to the intermediate transfer belt 5 and superimposed, and then the toner is transferred to the secondary transfer roller 7. Are applied to the transfer material P in a batch. The developer remaining on the intermediate transfer belt is removed by the cleaning device 18.
[0075]
  FIG. 4 shows an example of the transfer conveyance belt system. The transfer material P is biased by the suction roller 63 and is sucked and transported to the transfer transport belt 16. The image of each color formed on the electrophotographic photosensitive member is sequentially transferred to the transfer material P adsorbed on the transfer conveyance belt by applying a bias having a polarity opposite to that of the toner from the transfer roller 17 and superimposed, and then fixed. Heat fixing is performed by the device 15.
[0076]
  Next, a method for measuring each characteristic in the present invention will be described.
[0077]
  <Measurement method of belt circumference current value>
  The electroconductive belt 120 is stretched around the electrophotographic belt 120 to be measured by the resistance measuring apparatus shown in FIG. 7 with a tension of 19.6 N (2 kgf) and is rotated by the drive roller 123 in the direction of the arrow at a peripheral speed of 120 mm / sec. A voltage is applied from 121 and the current value is measured with an ammeter of 122, and a recorder (not shown) is used.For electrophotographybeltofThe current value for one round is recorded continuously. Then minimumCurrentValue and maximumLarge currentCompare values and maxCurrentValue / minimumCurrentCalculate how many times the difference in current value is. Measurement voltage is usually 1kV can be appropriately selected according to the resistance value of the electrophotographic belt.
[0078]
  <Measuring method of melt viscosity>
  Measuring device: Shimadzu Flow Tester CFT-500D manufactured by Shimadzu Corporation
Samples that have been reduced in diameter, such as pellets or powder, to enter the cylinder are used.
[0079]
  "Measurement condition"
  Load: 5.0kg
  Orifice area x length; 1 mm²× 1mm
  Measurement mode: Temperature rising method
  Preheating time: 120 seconds
  Temperature increase rate: 5 ° C / min
  Stroke: 20.0mm
  Measurement start temperature to ultimate temperature; 100 ° C to 300 ° C
  Measurement is started under the above conditions, and the temperature at the point where the viscosity is 10,000 Pa · s is read from the temperature-viscosity curve.
[0080]
  <Volume resistance measurement method>
  The measuring device uses an ultrahigh resistance meter R8340A (manufactured by Advantest) as the resistance meter, and the sample box TR42 (manufactured by Advantest) as the sample box, the main electrode is 3.0 mm in diameter, guard ring electrode Has an inner diameter of 41 mm and an outer diameter of 49 mm.
[0081]
  Samples are prepared as follows. First, the electrophotographic belt is cut into a circle having a diameter of 56 mm with a punching machine or a sharp blade. One side of the cut-out circular piece is provided with an electrode by a Pt-Pd vapor deposition film on the entire surface, and the other side is provided with a main electrode having a diameter of 3.0 mm and a guard electrode having an inner diameter of 38 mm and an outer diameter of 50 mm by a Pt-Pd vapor deposition film. Provide. The Pt—Pd vapor deposition film can be obtained by performing a vapor deposition operation for 2 minutes with mild sputtering E1030 (manufactured by Hitachi, Ltd.). The sample after the vapor deposition operation is used as a measurement sample.
[0082]
  The measurement atmosphere is 23 ° C./55%, and the measurement sample is previously left in the same atmosphere for 12 hours or more. The measurement is performed with a discharge of 10 seconds, a charge of 30 seconds, and a major of 30 seconds, and the measurement is performed at an applied voltage of 1 to 1000V.
[0083]
  The applied voltage is arbitrarily selected between 1-1000 V, which is a part of the range of voltages applied to the intermediate transfer member and transfer member used in the image forming apparatus of the present invention. Depending on the resistance value, thickness, dielectric breakdown strength, etc. of the sample, the applied voltage used can be changed in a timely manner within the range of the applied voltage.
[0084]
  <Thickness measurement method>
  The thickness unevenness of the belt of the present invention is measured over the entire circumference at a distance of 5 mm in the circumferential direction at a position 20 mm from the end of the belt in a dial gauge having a minimum value of 1 μm. This was done at both ends and all were averaged.
[0085]
【Example】
  Hereinafter, the present invention will be described in more detail with specific examples. In the examples,% means mass%.
[0086]
  Example 1
  PVDF (polyvinylidene fluoride) 68.4%
  Polyether ester amide 5.5%
  Polyolefin polyether 3.5%
  Fluorosurfactant 0.6%
  Metal oxide particles (non-conductive) 22.0%
[0087]
  The temperatures at which the melt viscosity was 10,000 Pa · s were 190 ° C for PVDF, 205 ° C for polyetheresteramide, and 150 ° C for polyolefin polyether.
[0088]
  The above blend was melted and kneaded at 210 ° C. with a biaxial extruder to uniformly disperse and mix each material, and extruded and cut with strands having a diameter of about 2 mm to obtain pellets. This is referred to as the belt molding compound of Example 1. Next, in the molding apparatus of FIG. 5, the molding die 103 was a single-layer annular die, and an annular slit having an outer diameter of 100 mm was used. The die slit was 0.8 mm. The belt molding compound sufficiently heated and dried was put into the material hopper 102 of this molding apparatus, heated and melted, and extruded from the die into a cylindrical shape at 210 ° C. An external cooling ring 105 is installed around the die to cool the extruded film by blowing air from the surroundings. Air was blown into the extruded tubular film from the gas introduction path 104 and expanded to a diameter of 138 mm, and then continuously taken out at a constant speed by a take-up device. The thickness was adjusted to 80 μm. The introduction of air is stopped when the diameter reaches a desired value. Further, the cylindrical film is cut by a cutting device 108 following the pinch roller. Then, it cut | disconnected by length 290mm and shape | molded the cylindrical film 1. FIG.
[0089]
  The cylindrical film was adjusted for size and surface smoothness and crease removal using a pair of cylindrical molds made of metals having different linear expansion coefficients. Cover the inner mold with a diameter of 140 mm, which has a high coefficient of linear expansion, with the tubular film 1 slightly extended, insert the inner mold into an outer mold with a smooth inner surface, heat to 190 ° C, and hold for 5 minutes after the temperature rises And cool. After cooling, it was removed from the cylinder, the end precision was cut, and a meandering preventing member was attached to the back of the belt end to produce a 140 mm diameter electrophotographic belt 1.
[0090]
  The volume resistivity of this electrophotographic belt 1 when 1 kV is applied is 9.8 × 10 6.⁹The difference between the maximum value and the minimum value of the current when 1 kV was applied by the apparatus of FIG. 7 was 1.18 times.
[0091]
  <Print test>
  The electrophotographic belt 1 was installed in the image forming apparatus shown in FIG. 1, and A4 size full color image printing was confirmed at a speed of 4 sheets per minute in an environment of 23 ° C./55%. As a result, there were no particularly problematic images such as image density unevenness or partial transfer omission, and the results were satisfactory.
[0092]
  Next, the uniformity of solid images and halftone images was tested in an environment of high temperature and high humidity (H / H) 32 ° C./80% and low temperature and low humidity (L / L) 10 ° C./10%. In order to acclimatize the electrophotographic belt in each environment, a good image with no particular problem was obtained when printing was performed after leaving it in the same environment for one day or more. In addition, (circle) evaluated that it was favorable, (triangle | delta) had no problem practically, and x was bad.
[0093]
  Subsequently, a storage stability test was conducted. The above cartridge is taken out from the main body, left in a very high temperature and high humidity environment of 40 ° C./95% for 7 days, returned to the environment of 23 ° C./55% again and left to stand for 24 hours. It was installed in the forming apparatus and an image check was performed as in the initial stage. As a result, an image almost different from the initial one was obtained, which was a good result. The results are shown in Table 2.
[0094]
  (Example 2)
  An electrophotographic belt 2 was produced in the same manner as in Example 1 except that the blending ratio was changed to the following, and a molding test and various performance confirmation tests were performed.
[0095]
  PVDF 72.0%
  Polyether ester amide 4.5%
  Polyolefin polyether 0.5%
  Fluorosurfactant 1.0%
  Metal oxide particles (non-conductive) 22.0%
[0096]
  The resistance value of the electrophotographic belt 2 is 5.1 × 10.¹⁰The difference in current value was 1.28 times. In the low-temperature and low-humidity print test, a point slightly inferior to Example 1 was observed, but an image having no practical problem was obtained. Good results were also obtained in the storage test. The test results are shown in Table 2.
[0097]
  Example 4
  An electrophotographic belt 4 was produced in the same manner as in Example 1 except that the diameter during molding was changed to 300 mm.
[0098]
  The volume resistivity of the electrophotographic belt 4 when applied with 1 kV is 1.2 × 10¹⁰The difference between the maximum value and the minimum value of the current when 1 kV was applied by the apparatus of FIG. 7 was 1.21 times.
[0099]
  The electrophotographic belt was attached to the image forming apparatus of FIG. 3 as an intermediate transfer belt, and an A4 size full color image print test was performed at a speed of 16 sheets per minute in an environment of 23 ° C./55%. As a result, there were no particularly problematic images such as image density unevenness or partial transfer omission, and the results were satisfactory. In the print test of high temperature and high humidity and low temperature and low humidity, good images were obtained as in Example 1. Since it is not a cartridge, a storage test was not performed. The results are shown in Table 2.
[0100]
  (Comparative Example 1)
  An electrophotographic belt 6 was produced in the same manner as in Example 1 except that the blending ratio was changed as follows, and a molding test and various performance confirmation tests were performed.
[0101]
  PVDF 62.8%
  Polyether ester amide 37.0%
  Fluorosurfactant 0.2%
[0102]
  The resistance value of the electrophotographic belt 6 is 8.8 × 10.¹⁰Ω · cm, 1 by the apparatus of FIG.kThe difference between the maximum value and the minimum value of the current when V was applied was 3.5 times.
[0103]
  Thereafter, the same print test as in Example 1 was performed, but the transfer efficiency was low and a decrease in density was observed, and the color misregistration exceeded the allowable range. In addition, image unevenness occurred in a high-temperature and high-humidity print test. These problems were many and the storage test was not performed. The results are shown in Table 2.
[0104]
  (Comparative Example 2)
  An electrophotographic belt 7 was produced in the same manner as in Example 1 except that the blending ratio was changed as follows, and a molding test and various performance confirmation tests were performed.
[0105]
  PVDF 85.0%
  Polyolefin polyether 3.8%
  Fluorosurfactant 1.2%
  Metal oxide particles (non-conductive) 10.0%
[0106]
  The resistance value of the electrophotographic belt 7 is 9.5 × 10.¹⁰The difference in current value was 1.15 times. In a print test in a low-temperature, low-humidity and high-temperature, high-humidity environment, polka dots and image density unevenness were remarkable. The results are shown in Table 2.
[0107]
[Table 1]
[0108]
[Table 2]
[0109]
【The invention's effect】
  As described above, according to the present invention, high image quality without polka dot transfer or uneven image density can be obtained in a wide range of environments, and good images can be obtained during long-term transportation under high temperature and high humidity. It has become possible to provide an electrophotographic belt, an image forming apparatus including the electrophotographic belt, and a process cartridge.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a full-color image forming apparatus using an electrophotographic belt and a process cartridge of the present invention.
FIG. 2 is a diagram showing a schematic configuration of an electrophotographic belt of the present invention and a process cartridge using the belt.
FIG. 3 is a diagram showing a schematic configuration of a full-color image forming apparatus using the electrophotographic belt of the present invention as an intermediate transfer belt.
FIG. 4 is a diagram showing a schematic configuration of a full-color image forming apparatus using the electrophotographic belt of the present invention as a transfer conveyance belt.
FIG. 5 is a diagram showing a schematic configuration of an electrophotographic belt (single layer) molding apparatus of the present invention.
FIG. 6 is a diagram showing a schematic configuration of an electrophotographic belt (two layers) molding apparatus of the present invention.
FIG. 7 is a diagram showing a method for measuring an entire circumference current value of an electrophotographic belt according to the present invention.
[Explanation 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 Charging member for cleaning
  10 Transfer material guide
  11 Paper feed roller
  12 Tension roller
  13 Cleaning device
  15 Fixing device
  16 Transfer conveyor belt
  17 Transfer roller
  18 Cleaning device
  30, 31, 33 Bias power supply
  32 Primary charger power supply
  41 Yellow color developing device
  42 Magenta color developing device
  43 Cyan developing device
  44 Black color developing device
  51 Photosensitive belt
  52 Driving roller
  53 Followed roller
  63 Suction roller
  100, 101 single screw extruder
  102 hopper
  103 annular die
  104 Gas introduction path
  105 External cooling ring
  106 Stabilizer
  107 Pinch roller
  108 cutting equipment
  110 Cylindrical film
  120 Electrophotographic belt
  121 Conductive rubber roller
  122 Ammeter
  123 Drive roller
  P transfer material

Claims (8)

Used as an intermediate transfer belt or transfer conveyance belt of an image forming apparatus for transferring a toner image obtained by visualizing an electrostatic latent image formed on an electrophotographic photoreceptor with toner onto a transfer material by electrostatic means. In electrophotographic belts,
The electrophotographic belt contains at least polyvinylidene fluoride, polyetheresteramide, and polyolefin polyether;
An electrophotographic belt characterized in that the maximum current value measured by the following current value measurement method is in the range of 1.18 times to 1.28 times the minimum current value:
<Current value measurement method>
(I) An electrophotographic belt for measuring resistance is stretched with a tension of 19.6 N (2 kgf) using two rollers including a driving roller. An ammeter is connected to a roller that is not the driving roller of the two rollers. The electrophotographic belt stretched between a roller that is not a driving roller and a conductive rubber roller among the two rollers is sandwiched,
(Ii) Next, a voltage is applied from the conductive rubber roller while rotating the stretched electrophotographic belt with the driving roller at a peripheral speed of 120 mm / sec, and the current value is measured with the ammeter. And the recorder continuously records the current value for one round of the electrophotographic belt.
(Iii) Next, among the continuously recorded current values, how many times the maximum current value is the minimum current value is obtained. An electrophotographic photoreceptor;
Charging means and exposure means for forming an electrostatic latent image on the electrophotographic photosensitive member;
Developing means for visualizing the electrostatic latent image with toner to obtain a toner image;
An intermediate transfer belt having a contact portion with the electrophotographic photosensitive member;
Primary transfer means for primary transfer of the toner image from the electrophotographic photosensitive member to the intermediate transfer belt at the contact portion;
In an electrophotographic belt used as the intermediate transfer belt of an image forming apparatus having secondary transfer means for secondary transfer of the toner image on the intermediate transfer belt to a transfer material,
The electrophotographic belt contains at least polyvinylidene fluoride , polyetheresteramide, and polyolefin polyether ;
1 the maximum current value measured by the following current measurement method is minimum current value. 18 times to 1 . Electrophotographic belt characterized by being in the range of 28 times :
<Current value measurement method>
(I) An electrophotographic belt for measuring resistance is stretched with a tension of 19.6 N (2 kgf) using two rollers including a driving roller. An ammeter is connected to a roller that is not the driving roller of the two rollers. The electrophotographic belt stretched between a roller that is not a driving roller and a conductive rubber roller among the two rollers is sandwiched,
(Ii) Next, a voltage is applied from the conductive rubber roller while rotating the stretched electrophotographic belt with the driving roller at a peripheral speed of 120 mm / sec, and the current value is measured with the ammeter. And the recorder continuously records the current value for one round of the electrophotographic belt.
(Iii) Next, among the continuously recorded current values, how many times the maximum current value is the minimum current value is obtained . Temperature of the melt viscosity of the polyolefin polyether is 10000 Pa · s is, the melt viscosity of the polyvinylidene fluoride rather lower than the temperature at which the 10000 Pa · s, the melt viscosity of the polyetheresteramide is 10000 Pa · s Temperature but electrophotographic belt according melt viscosity to high have claim 1 or 2 than the temperature at which the 10000 Pa · s of the polyvinylidene fluoride. The total content of the polyetheresteramide and Po Li olefin polyethers contained in the electrophotographic belt is 4 to 35 wt%, and polyetheresteramide: polyolefin polyether 1: 9 to 9: The belt for electrophotography according to any one of claims 1 to 3, which is in the range of 1. An electrophotographic photoreceptor;
Charging means and exposure means for forming an electrostatic latent image on the electrophotographic photosensitive member;
Developing means for visualizing the electrostatic latent image with toner to obtain a toner image;
An intermediate transfer belt having a contact portion with the electrophotographic photosensitive member;
Primary transfer means for primary transfer of the toner image from the electrophotographic photosensitive member to the intermediate transfer belt at the contact portion;
In an image forming apparatus having secondary transfer means for secondary transfer of the toner image on the intermediate transfer belt to a transfer material,
An image forming apparatus, wherein the intermediate transfer belt is the electrophotographic belt according to claim 1 . The image forming apparatus further includes a cleaning unit for cleaning toner remaining on the intermediate transfer belt after the secondary transfer by the secondary transfer unit,
The cleaning unit is a cleaning unit that applies a charge having a polarity opposite to that of the primary transfer by the primary transfer unit to the remaining toner and returns the residual toner to the electrophotographic photosensitive member simultaneously with the primary transfer. The image forming apparatus according to claim 5 . 7. A process cartridge configured to be detachable from a main body of the image forming apparatus according to claim 5 or 6 , wherein the process cartridge is supported integrally with the electrophotographic photosensitive member and the intermediate transfer belt. The process cartridge further includes a cleaning unit for cleaning toner remaining on the intermediate transfer belt after the secondary transfer by the secondary transfer unit,
The cleaning unit is a cleaning unit that applies a charge having a polarity opposite to that of the primary transfer by the primary transfer unit to the remaining toner and returns the residual toner to the electrophotographic photosensitive member simultaneously with the primary transfer. The process cartridge according to claim 7 .