JP3950751B2 - Electrophotographic belt, electrophotographic photosensitive member-intermediate transfer belt integrated cartridge, image forming apparatus, and method for producing electrophotographic belt - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an electrophotographic belt and an electrophotographic photosensitive member-intermediate transfer belt integrated cartridge.,Image forming apparatusAnd manufacturing method of electrophotographic beltAbout.
[0002]
[Prior art]
An image forming apparatus that uses an intermediate transfer member is a color image forming device that sequentially stacks and transfers a plurality of component color images of color image information and multicolor image information, and outputs an image formed product in which color images and multicolor images are synthesized and reproduced. It is effective as an apparatus, a multicolor image forming apparatus, or an image forming apparatus having a color image forming function and a multicolor image forming function.
[0003]
A schematic view of an example of an image forming apparatus using an intermediate transfer belt as an intermediate transfer member is shown in FIG.
[0004]
FIG. 1 shows a color image forming apparatus (copier or laser beam printer) using an electrophotographic process. A medium resistance belt is used as the intermediate transfer belt 5.
[0005]
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 carrier, and is rotationally driven at a predetermined peripheral speed (process speed) in the counterclockwise direction indicated by an arrow. Is done.
[0006]
The photosensitive drum 1 is uniformly charged to a predetermined polarity / potential by the primary charger 2 during the rotation process, and then image exposure means 3 (color separation / imaging exposure optical system for color original image, image) A first color component image (for example, yellow) of a target color image by receiving an image exposure by a scanning exposure system or the like by a laser scanner that outputs a laser beam modulated corresponding to a time-series electric digital pixel signal of information An electrostatic latent image corresponding to the color component image) is formed.
[0007]
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 on 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.
[0008]
The intermediate transfer belt 5 is driven to rotate in the clockwise direction at the same peripheral speed as that of the photosensitive drum 1.
[0009]
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 intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer belt 5 by the electric field formed by the primary transfer bias.
[0010]
The surface of the photosensitive drum 1 after the transfer of the first color yellow toner image to the intermediate transfer belt 5 is cleaned by the cleaning device 13.
[0011]
Similarly, 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 a composite color corresponding to the target color image is obtained. A toner image is formed.
[0012]
Reference numeral 7 denotes a secondary transfer roller, which is supported in parallel with the secondary transfer counter roller 8 so as to be separated from the lower surface of the intermediate transfer belt 5.
[0013]
A primary transfer bias for sequentially superimposing and transferring toner images of the first to fourth colors 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.
[0014]
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.
[0015]
When 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, the secondary transfer roller 7 is brought into contact with the intermediate transfer belt 5 and a 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. With this secondary transfer bias, the composite color toner image is transferred (secondary transfer) 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 fixed by heating.
[0016]
After the image transfer to the transfer material P is completed, a cleaning charging member 9 of a cleaning device is brought into contact with the intermediate transfer belt 5 and is transferred to the transfer material P by applying a bias having a polarity opposite to that of the photosensitive drum 1. Instead, a charge having a polarity opposite to that of the photosensitive drum 1 is applied to the toner (transfer residual toner) remaining on the intermediate transfer belt 5. Reference numeral 33 denotes a bias power source.
[0017]
The transfer residual toner is electrostatically transferred to the photosensitive drum 1 at and near the nip portion with the photosensitive drum 1 to clean the intermediate transfer belt.
[0018]
In a color electrophotographic apparatus having an image forming apparatus using the above-described intermediate transfer belt, a second image carrier is pasted or adsorbed on a transfer drum, which is a conventional technique, and from there on the first image carrier. Compared with a color electrophotographic apparatus having an image forming apparatus for transferring an image, for example, a transfer apparatus as described in JP-A-63-301960, the transfer material as the second image carrier is not Since images can be transferred from the intermediate transfer belt without the need for processing and control (eg, gripping, adsorbing, giving curvature, etc.), thin paper (40 g / m²Paper) to thick paper (200g / m²Paper), the second image carrier can be selected in a wide variety of ways regardless of the width, width, length, or thickness.
[0019]
Because of these advantages, color copiers, color printers and the like using an intermediate transfer belt have already started to move in the market.
[0020]
Next, FIG. 2 shows a schematic diagram of an example of an image forming apparatus using a transfer belt as a transfer member.
[0021]
The image forming apparatus shown in FIG. 2 forms toner images of different colors on a plurality of photoconductors as one type of color image forming apparatus of the color separation image superposition transfer method, and sequentially forms on each photoconductor. A toner image on each photoconductor is transferred to a single transfer material conveyed in contact, and a full color image is obtained.
[0022]
The image forming apparatus shown in FIG. 2 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. 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.
[0023]
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 driving roller 311, the driven roller 312 and the tension roller 313. The belt 314 includes transfer chargers 315Y, 315M, 315C, and 315BK disposed to face the photosensitive drums 301Y, 301M, 301C, and 301BK of the image forming units I to IV, respectively.
[0024]
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 recording papers P as a recording medium. One recording paper 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.
[0025]
A separation charger 316 and a fixing device 317 are disposed on the downstream side in the conveyance direction of the recording paper P in the apparatus main body 320, and a paper discharge tray 318 is attached outside the apparatus main body 320.
[0026]
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 uniformly made by the primary charging rollers 302Y, 302M, 302C, and 302BK, respectively. To be charged. When the exposure units 303Y, 303M, 303C, and 303BK perform exposure according to image information on the photosensitive drums 301Y, 301M, 301C, and 301BK thus charged, the photosensitive drums 301Y, 301M, and 301C, 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.
[0027]
On the other hand, the recording paper 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 at the timing by the registration roller 309 and is transferred to the transfer belt 314 of the transfer device 310. The recording paper P is adsorbed and moved together with the image forming units I to IV. In the process, the recording paper P is subjected to transfer chargers 315Y, 315M, 315C, and 315BK, respectively, so that a yellow toner image, a magenta toner image, The cyan toner image and the black toner image are transferred in a superimposed manner.
[0028]
Then, the recording paper 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 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. The color image forming apparatus using the transfer belt has an advantage that the color image is formed in one process because the color images are superimposed and transferred while the transfer paper is sequentially conveyed to each recording apparatus, so that the image output time is fast.
[0029]
Because of these advantages, color copying machines, color printers, and the like using transfer belts have already started to move in the market.
[0030]
Next, the electrophotographic photosensitive member-intermediate transfer belt integrated cartridge will be described. The life of the intermediate transfer belt is shorter than that of the apparatus main body, and at present, replacement is essential. At the same time, it is necessary to install and process a waste toner container that collects the developer (hereinafter referred to as toner) remaining on the intermediate transfer belt. In addition to these, many parts such as an electrophotographic photosensitive member, a developing device, and a developer need to be replaced in a printer or a copying machine. Japanese Patent Laid-Open No. 8-137181 proposes a method in which these replacement parts are unitized and easily detached from the apparatus main body. Has been made.
[0031]
However, this means requires a large number of replacement units and complicates the user operation. Furthermore, since each unit is designed and arranged independently, problems such as an increase in the size of the main body and an increase in cost arise.
[0032]
As a means for solving this problem, it is preferable to attach and detach the electrophotographic photosensitive member, which is a replacement part, and the intermediate transfer belt as an integral unit at the same time and replace them. Japanese Patent Laid-Open Nos. 6-110261 and 10- No. 177329 and Japanese Patent Laid-Open No. 11-30944.
[0033]
[Problems to be solved by the invention]
However, a color electrophotographic apparatus using an electrophotographic belt such as an intermediate transfer belt or a transfer belt, or an electrophotographic photosensitive member-intermediate transfer belt integrated cartridge fully utilizes the advantages described above and is true for the user. It does not function as a device that is expected and satisfactory. In providing such an intermediate transfer belt, an image forming apparatus using the transfer belt, and an electrophotographic photosensitive member-intermediate transfer belt integrated cartridge, there are still problems to be overcome.
[0034]
When an electrophotographic belt is produced from a thermoplastic resin mixture, the molding method is mainly extrusion molding. However, since extrusion molding is continuous molding, it is difficult to stabilize the shape. In particular, when the melt viscosity of the molding resin changes abruptly due to temperature changes, it is difficult to stabilize the shape because the melt viscosity changes greatly due to slight temperature changes of the die. If the shape is not stabilized by this, waviness may occur on the belt surface.
[0035]
Another factor is that when the extrusion die is a spiral die, it is basically difficult to generate spider marks with minute film thickness unevenness, but the melt viscosity of the molding resin. When the temperature changes rapidly due to a temperature change, the melt viscosity changes greatly due to a slight temperature change in the spiral portion, so that a spider mark may occur, which may cause the belt to swell.
[0036]
When such waviness occurs in the intermediate transfer belt, when a four-color full-color image is output, the transfer efficiency of the convex portion of the surface waviness of the intermediate transfer belt is high when the toner image on the first color photosensitive drum is transferred, Only the convex portion of the image has a high density, and unevenness occurs in the image.
[0037]
Next, when the second color is transferred to the intermediate transfer belt, the portion where the second color toner image is not superimposed on the first color toner image and the portion where the first color toner image is placed on the intermediate transfer belt is photosensitive. When contacted with the drum, a phenomenon may occur in which part of the toner on the intermediate transfer belt returns to the photosensitive drum (hereinafter referred to as retransfer) (this phenomenon occurs when the primary transfer voltage is high). Easy to happen). At this time, the toner on the convex portion of the surface waviness of the intermediate transfer belt may return more to the photosensitive drum than the concave portion, and the image density of the convex portion may be lowered.
[0038]
In addition, when the second color toner image is added to the first color toner image, the retransfer of the first color convex portion obstructs the transfer of the second color toner image and the convex portion image density is lowered. There is. The same phenomenon occurs in the third color and the fourth color, and when the image is finally transferred from the intermediate transfer belt to the second image carrier (paper or the like), the density of the convex portion is low and the density of the concave portion is high. In some cases, the image has an image unevenness equivalent to the shape of the swell.
[0039]
In addition, when the cleaning process for returning the transfer residue to the photosensitive drum is performed on the photosensitive drum, the residual transfer from the second image bearing member corresponding to the concave part is difficult to return to the photosensitive drum from the convex part, and the cleaning is insufficient. As a result, the load on the apparatus becomes large because a large amount of untransferred toner is cleaned, and the cleaning apparatus becomes considerably complicated and expensive.
[0040]
As these countermeasures, for example, see JP-A-59-50475, JP-A-59-202477, JP-A-3-242667, JP-A-4-303869, and JP-A-4-303871. The surface roughness of the intermediate transfer belt is considered to be small, but this surface roughness corresponds to the surface of the toner particles, and in the case of the waviness conditions as described above, the surface roughness is reduced. However, transfer unevenness may occur.
[0041]
In addition, if the intermediate transfer belt is greatly swelled, the tension may be uneven when the intermediate transfer belt is stretched with a certain tension. In the case of a thermoplastic resin, stress cracking may occur and the intermediate transfer belt may be torn. .
[0042]
These belt tears often occur from the end where more force is applied, and as a countermeasure, there is a method of stretching a reinforcing tape, but it is difficult to apply a reinforcing tape uniformly, if it cannot be applied uniformly, In some cases, the running performance of the intermediate transfer belt is affected, and the cost increases due to an increase in the number of steps for applying the tape.
[0043]
Furthermore, in the case of an electrophotographic photosensitive member-intermediate transfer belt integrated cartridge, it may be left in a high-temperature and high-humidity environment for a long time, causing the intermediate transfer belt to contract or relax, and the undulation is perpendicular to the circumferential direction of the intermediate transfer belt. Even in the case of occurrence in the direction, wrinkles in the circumferential direction may occur due to the difference in the circumferential length of the waviness portion, and the wrinkles may cause image unevenness in the same way as waviness.
[0044]
The same can be said for the transfer belt.
[0045]
As described above, a color electrophotographic apparatus using an electrophotographic belt such as an intermediate transfer belt or a transfer belt, and an image forming apparatus that completely solves the problems in an electrophotographic photosensitive member-intermediate transfer belt integrated cartridge have not yet been obtained. Absent.
[0046]
Accordingly, an object of the present invention is to solve the above-mentioned problems, and is an electrophotographic belt, an electrophotographic photosensitive member-intermediate transfer belt integrated type, which has no image unevenness, is highly durable, is easy to maintain, and can be downsized. A cartridge and an image forming apparatus are realized.
[0047]
That is, according to the present invention, when toner moves from the surface of the photosensitive drum, which is the first image carrier, to the intermediate transfer belt, image unevenness does not occur in the wavy portion, and retransfer is performed when a multicolor image is output. High-durability electrophotographic belt and electrophotographic photosensitive member in which there is no increase in the amount of re-transfer of waviness convex portions at the time, there is no occurrence of uneven transfer of the finally obtained image, and belt tearing from the end portion does not occur An intermediate transfer belt integrated cartridge and an image forming apparatus are provided.
[0048]
[Means for Solving the Problems]
  In the present inventionAccordingly, a thermoplastic resin mixture having a flow tester outflow start temperature of + 15 ° C. and a viscosity at a flow tester outflow start temperature of + 15 ° C. of 1.2 to 50 times is melt-extruded from the annular die. The diameter of the tubular film is controlled by injecting or sucking gas into the obtained tubular film to adjust the internal volume, and the tubular film is supported until the tubular film is cooled and solidified. Forming the cylindrical film from the annular die without using a member, and then manufacturing the cylindrical body of the thermoplastic resin mixture by a method of cutting;
  For electrophotography made of a thermoplastic resin mixture used in an image forming apparatus, which is produced by heating and pressing and contacting the cylindrical body inside a cylindrical rigid body having a diameter larger than the diameter of the cylindrical body A belt,
  The electrophotographic belt has a surface waviness having an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction, the average wave height of the surface waviness is 30 μm or less, and at least one end portion in the longitudinal direction of the belt An electrophotographic belt is provided in which the film thickness is 60% or more and 95% or less with respect to the belt center film thickness.
  In addition, according to the present invention, the electrostatic latent image formed on the electrophotographic photosensitive member is visualized with a developer, and the resulting image is transferred to an intermediate transfer belt, and transferred to the intermediate transfer belt. In addition, the image forming apparatus main body further including a secondary transfer step of transferring the image to a transfer material, and an electrophotographic photosensitive member-intermediate transfer belt integrated cartridge detachably configured,
  An electrophotographic photosensitive member-intermediate transfer belt integrated cartridge is provided in which the intermediate transfer belt is the above-described electrophotographic belt.
  In addition, according to the present invention, the electrostatic latent image formed on the electrophotographic photosensitive member is visualized with a developer, and the resulting image is transferred to an intermediate transfer belt, and transferred to the intermediate transfer belt. In the image forming apparatus using the main body of the image forming apparatus having a secondary transfer step of further transferring the image to a transfer material,
  An image forming apparatus is provided in which the intermediate transfer belt is the electrophotographic belt.
  Furthermore, according to the present invention, the film has surface waviness having an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction, the average wave height of the surface waviness is 30 μm or less, and at least one end film in the longitudinal direction of the belt A method for producing an electrophotographic belt made of a thermoplastic resin used in an image forming apparatus, the thickness of which is 60% or more and 95% or less with respect to the belt center film thickness,
It is obtained by melting and extruding a thermoplastic resin mixture in which the viscosity at the flow tester's outflow start temperature + 5 ° C is 1.2 to 50 times the viscosity at the flow tester's outflow start temperature + 15 ° C. The diameter of the tubular film is controlled by injecting or sucking gas into the tubular film to adjust the internal volume, and a member that supports the tubular film until the tubular film is cooled and solidified. Forming the cylindrical film from the annular die without using it, and then manufacturing the cylindrical body of the thermoplastic resin mixture by a method of cutting;
  Heating and pressing the cylindrical body inside a cylindrical rigid body having a diameter larger than the diameter of the cylindrical body; and
A method for producing an electrophotographic belt is provided.
[0049]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, for the thermoplastic resin mixture constituting the electrophotographic belt, the viscosity at the outflow start temperature + 5 ° C. is 1.2 times to 50 times the viscosity at the outflow start temperature + 15 ° C. of the flow tester. Therefore, when extrusion molding is performed, the viscosity change due to temperature change is reduced, and even if there is a slight change temperature of the die during molding, the change in viscosity is small, which causes uneven discharge when discharged from the die. When the spiral die is used, the change in viscosity inside the die is small, so the spider mark does not occur, the shape can be stabilized, the surface waviness of the electrophotographic belt surface, That is, by setting the average wave height of the surface waviness of the electrophotographic belt having the surface waviness with an average wavelength of 0.1 mm or more and less than 20 mm to 30 μm or less. At the time of primary transfer, the difference in the distance that the toner moves from the surface of the photosensitive drum, which is the first image carrier, to the electrophotographic belt decreases the difference between the convex and concave portions of the electrophotographic belt. Transfer unevenness due to the toner remaining in the concave portion after the secondary transfer, and reduction of transfer unevenness due to retransfer by eliminating the retransfer of the convex portion at the time of the second primary transfer. Cleaning defects can be reduced.
[0050]
Also, if the viscosity at the outflow start temperature + 5 ° C is less than 1.2 times the viscosity at the outflow start temperature + 15 ° C of the flow tester, the change in viscosity is too small and the die shape itself during extrusion is retained. The swell may increase, which is not preferable.
[0051]
If the viscosity at the outflow start temperature + 5 ° C is greater than 50 times the viscosity at the outflow start temperature + 15 ° C of the flow tester, the viscosity change is too large and the extrusion molding is not stable, and spider marks may be generated. Since it occurs, it is not preferable.
[0052]
Although the surface wave of the surface of the electrophotographic belt, that is, the average wave height of the surface wave of the electrophotographic belt having an average surface wave of 0.1 mm or less and less than 20 mm is 30 μm or less, the effect of the present invention can be obtained. The average wave height is preferably 5 μm or less. Further, transfer unevenness occurs when the average wavelength of the surface waviness is 0.1 mm or more and less than 20 mm on the average, but the more prominent generation region is 0.5 mm or more and less than 10 mm. This seems to be due to the sudden rise of the swell.
[0053]
Further, in the case of the electrophotographic photosensitive member-intermediate transfer belt integrated cartridge, the thermoplastic resin mixture constituting the intermediate transfer belt has an outflow start temperature of + 5 ° C. with respect to the viscosity at the outflow start temperature of the flow tester of + 15 ° C. The average wave height of the surface waviness of the intermediate transfer belt having a surface waviness of an average transfer belt having a wavelength of 0.1 mm or more and less than 20 mm is obtained. By setting the thickness to 30 μm or less, the difference in the distance that the toner moves from the surface of the photosensitive drum, which is the first image carrier, to the intermediate transfer belt is reduced, and the difference between the wavy convex portion and the concave portion of the intermediate transfer belt is reduced. Transfer unevenness due to retransfer by reducing transfer unevenness at the time of primary transfer and elimination of retransfer of convex portions at the time of the second primary transfer Even if the intermediate transfer belt contracts or relaxes when left in a high-temperature and high-humidity environment for a long period of time, the cleaning failure due to toner remaining in the concave portion after secondary transfer is reduced. By setting the average wave height of the surface waviness of the intermediate transfer belt having the surface waviness with an average wavelength of 0.1 mm or more and less than 20 mm to 30 μm or less, it is possible to prevent circumferential wrinkles due to a difference in circumferential length. This is considered to be because the difference in the undulation portion of the belt relaxation and contraction is reduced because the undulation is small.
[0054]
Also, by setting the film thickness at least on one side of the electrophotographic belt to 60% or more and 95% or less with respect to the film thickness at the center of the belt, bending breakage is less likely to occur at the end than at the center of the belt. Is no longer necessary. The reason why bending breakage is less likely to occur is that when the film thickness is thin, the difference in how the belt front and back surfaces are stretched during bending is reduced, and the load on the stretched part is reduced, so the film thickness is thin. It is thought that it becomes difficult to break. Further, in the case where at least one end portion of both end portions is reinforced with a rib or the like, only the unreinforced side may be thin.
[0055]
The center film thickness is an average value when the film thickness at the center of the belt is measured at 10 points at equal intervals in the circumferential direction, and the end film thickness is 5 points from the belt end toward the center every 2 mm. It is an average value obtained by measuring 10 points at the same interval in the circumferential direction.
[0056]
Here, the measurement method of the flow tester is shown below. The flow tester measurement of the present invention was performed using a flow tester CFT-500D manufactured by Shimadzu Corporation.
[0057]
<Measurement method>
1 g of a resin compound or belt that has been pulverized so that the outer diameter is about 2 to 3 mm is accurately weighed and measured under the following conditions. The viscosity at the outflow start temperature + 5 ° C. and the outflow start temperature + 15 ° C. Read the viscosity.
[0058]
<Measurement conditions>
Load: 50 N; Orifice diameter: 1 mm diameter, length 1.0 mm; Rate of temperature increase: 5 ° C./min; Measurement start temperature: 150 ° C .; Preheating time: 120 seconds
In addition, the surface waviness used in the present invention is measured based on JIS B0610, and a filtered centerline waviness curve is used. The average wavelength of the present invention is represented by the average interval Sm (ISO) of the unevenness of the curve obtained by the filtered center line undulation curve, and the average wave height is the ten-point average roughness of the curve obtained by the filtered center line undulation curve. Rz (JIS). At this time, the low-frequency cutoff is 0.25 mm, the high-frequency cutoff is 8 mm, the measurement length is 80 mm, and the measurement speed is 2 mm / s.
[0059]
Further, the thermoplastic resin mixture used in the present invention is a resin mixture having thermoplasticity. For example, even if a thermoplastic resin and a thermosetting resin powder are mixed, the final resin mixture is What is necessary is just to have thermoplasticity.
[0060]
The thermoplastic resin as the main material of the thermoplastic resin mixture used for the electrophotographic belt of the present invention is not particularly limited as long as it satisfies the characteristics of the present invention. For example, olefins such as polyethylene and polypropylene Resin, polystyrene resin, acrylic resin, polyester resin, polycarbonate resin, sulfur-containing resin such as polysulfone, polyethersulfone and polyphenylene sulfide, fluorine-containing resin such as polyvinylidene fluoride and polyethylene-tetrafluoroethylene copolymer, A polyurethane resin, a silicone resin, a ketone resin, a polyvinylidene chloride resin, a thermoplastic polyimide resin, a polyamide resin, a modified polyphenylene oxide resin, etc., and one or more of these various modified resins and copolymers can be used. However, it is not limited to the said material.
[0061]
Next, the additive to be mixed for adjusting the electric resistance value of the intermediate transfer belt of the present invention is not particularly limited, but as the conductive filler for adjusting the resistance, carbon black and various conductive metal oxides are used. Non-filler resistance regulators include low molecular weight ionic conductive materials such as various metal salts and glycols, antistatic resins containing ether bonds and hydroxyl groups in the molecule, or organic polymers exhibiting electronic conductivity. Such as a compound.
[0062]
Moreover, there exists a method of mixing an inorganic filler as a method of adjusting the melt viscosity of this invention. Examples of such inorganic fillers include mica, kaolins, bentonite, acid clay, barium sulfate, zinc oxide, various whiskers and the like, and one or more kinds of these fillers are appropriately selected. It is not limited to these.
[0063]
The flow tester data of the electrophotographic belt used in the present invention can be adjusted by selecting the raw materials as described above. As another flow tester viscosity adjustment method, when the viscosity at the outflow start temperature + 5 ° C. is less than 1.2 times the viscosity at the outflow start temperature + 15 ° C. of the flow tester, 1.2 times or more of the resin is mixed There is. When the viscosity at the outflow start temperature + 5 ° C. is greater than 50 times the viscosity at the outflow start temperature + 15 ° C. of the flow tester, there is a method of mixing 50 times or less resin. Furthermore, as a resin selection method, there is a method of mixing a sharp molecular weight distribution and a broad one. Generally, when the molecular weight distribution is sharp, the flow tester data may be 50 times or more, and when the molecular weight distribution is broad, the flow tester data may be 1.2 times or less. In combination, melting characteristics within the scope of the present invention can be obtained. However, it is not necessarily limited to these, and any method may be used as long as it has the melting characteristics of the present invention.
[0064]
In order to reduce the size and cost of the electrophotographic photosensitive member-intermediate transfer belt integrated cartridge, the shape of the electrophotographic photosensitive member incorporated in the cartridge is important. Accordingly, the electrophotographic photosensitive member is preferably a photosensitive drum having a diameter of 60 mm or less, which has a simple driving mechanism and can be easily miniaturized.
[0065]
For the same purpose, the intermediate transfer belt is preferably stretched by two rollers because the reduction in the number of parts and the reduction in size are promoted.
[0066]
The tension roller that applies tension to the intermediate transfer belt preferably slides at least 1 mm or more in the extension direction of the intermediate transfer belt in order to cope with the extension of the intermediate transfer belt, and is driven reliably without slipping the intermediate transfer belt. For this purpose, it is preferable to stretch the intermediate transfer belt with a force of 5 N or more.
[0067]
In order to reduce the size and cost of the cartridge, it is preferable that the intermediate transfer belt cleaning mechanism uses a primary transfer simultaneous cleaning method in which the transfer residual toner is charged to a reverse polarity and is returned to the photosensitive member at the same time during the primary transfer. Specifically, a voltage is applied to a charging member such as a cleaning roller that is detachably arranged on the intermediate transfer belt to give the secondary transfer residual toner a charge having a polarity opposite to that at the time of primary transfer. It is means for returning to the photoreceptor by a transfer electric field. A blade, a corona charger, or the like may be used as a means for charging the toner to the reverse polarity. The toner returned from the intermediate transfer belt to the photoconductor is removed by a photoconductor cleaning mechanism such as a cleaning blade. According to this method, cleaning cartridges and the like are arranged on both the photosensitive member and the intermediate transfer belt, and compared with a method in which a waste toner feeding mechanism and a container are installed, there is a great effect in reducing the size and cost of the cartridge. Such a cleaning device is desirably integrated with the electrophotographic photosensitive member-intermediate transfer belt integrated cartridge. This is because the cleaning device also needs to be replaced due to deterioration due to image output or the like, but the integration reduces the number of replacement units and simplifies the user's operation.
[0068]
In the electrophotographic photosensitive member-intermediate transfer belt integrated cartridge, the cartridge is separable into an electrophotographic photosensitive unit having an electrophotographic photosensitive member and an intermediate transfer belt unit having the intermediate transfer belt. It is desirable to have connecting means for connecting the photosensitive unit and the intermediate transfer belt unit.
[0069]
By adopting this configuration, after the user removes the process cartridge for the color electrophotographic apparatus from the main body of the color electrophotographic apparatus, the user separates the removed process cartridge into the electrophotographic photosensitive member unit and the intermediate transfer belt unit, and the service life This is because it is possible to replace only the unit that has reached the above, reducing the user's cost burden, and for the producer side, there is an advantage that can be dealt with only by replacing the defective unit.
[0070]
Further, the resistance value of the electrophotographic belt needs to be adjusted. The range of the volume resistivity of the intermediate transfer belt that can provide a good image is between 1E + 6 Ωcm and 8E + 13 Ωcm. If the volume resistivity is less than 1E + 6 Ωcm, the resistance is too low to obtain a sufficient transfer electric field, resulting in image omission and roughness. On the other hand, if the volume resistivity is higher than 8E + 13 Ωcm, it is necessary to increase the transfer voltage, resulting in an increase in the size of the power source and an increase in cost.
[0071]
The thickness of the intermediate transfer belt is preferably in the range of 40 μm to 300 μm. If it is 40 μm or less, molding stability is insufficient, thickness unevenness tends to occur, durability strength is insufficient, and belt breakage or cracking may occur. 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 at the stretched shaft portion of a printer or the like increases, and problems such as image scattering due to contraction of the outer surface are likely to occur. Further, there is a problem that the bending durability is lowered and the rigidity of the belt becomes too high to increase the driving torque, resulting in an increase in size and cost of the main body.
[0072]
As a method for forming an electrophotographic belt, a seamless belt can be manufactured, and a manufacturing method with high manufacturing efficiency and low cost is preferable. As a means for this, there is a method in which a belt is manufactured by continuous melt extrusion from an annular die and then cutting to a required length. For example, inflation molding is suitable.
[0073]
One embodiment of the production method of the present invention will be described below. However, this does not limit the present invention.
[0074]
FIG. 3 shows an example of a molding apparatus relating to the electrophotographic belt of the present invention. This device basically consists of an extruder, an extrusion die, and an air blowing device.
[0075]
First, based on a desired formulation, a molding resin, a conductive agent, an additive, and the like are premixed in advance, and 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 raw material for molding has a melt viscosity that enables belt forming in a later 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 enter the annular die 103. The annular die 103 is provided with an air introduction passage 104. When air is blown into the center of the annular die 103 from the air introduction passage 104, the melt that has passed through the die 103 expands and expands in the radial direction, and the cylinder The film 110 is formed.
[0076]
The gas blown at this time can be selected from nitrogen, carbon dioxide, argon, etc., in addition to air. The expanded tubular film is pulled upward while being cooled by the external cooling ring 105. In a normal inflation apparatus, a method is used in which a tube is crushed from the left and right by a stabilizer plate 106, folded into a sheet shape, pinched by a pinch roller 107 so that air inside does not escape, and taken at a constant speed. Next, the taken film is cut by a cutting device 108 to obtain a belt having a desired size.
[0077]
In addition, the above explanation was related to a single layer belt, but in the case of two layers, an extruder 101 is additionally arranged as shown in FIG. The kneaded melt of the extruder 101 is fed into the annular die 103, and two layers can be expanded and expanded simultaneously to obtain a two-layer belt.
[0078]
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.
[0079]
The thickness ratio between the annular die and the molded cylindrical film in the present invention is the ratio of the thickness of the molded cylindrical film to the width of the gap (slit) of the annular die, and the latter is compared with the former. It is necessary to be 1/3 or less, more preferably 1/5 or less.
[0080]
Similarly, the ratio of the diameter of the annular die to the formed cylindrical film is the ratio of the outer diameter of the tubular film 110 to the outer diameter of the slit of the annular die 103, and is 50% to 400%. % Range is preferred.
[0081]
These represent the stretched state of the material, and when the thickness ratio is larger than 1/3, the stretching is insufficient, and problems such as a decrease in strength and unevenness in resistance and thickness occur. On the other hand, when the outer diameter exceeds 400 percent or less than 50%, the film is stretched excessively, so that it is difficult to reduce the molding stability or to secure the thickness necessary for the present invention.
[0082]
Also, a method of performing molding by bringing a cylindrical body of a thermoplastic resin formed in a cylindrical shape, which is smaller than the diameter of the cylindrical rigid body in advance, into a cylindrical rigid body according to the present invention, at least in a diametrical direction, by heating and pressing contact As an example of the outer cylindrical rigid body, a blow molding method, a stretch blow molding method, and two types of dies having different thermal expansion coefficients as disclosed in Japanese Patent Laid-Open No. 5-31818 are used. An inner cylindrical rigid body having a thermal expansion coefficient larger than the thermal expansion coefficient is disposed, and a thermoplastic resin cylinder formed in a cylindrical shape on the outer periphery of the inner cylindrical body in advance, which is smaller than the diameter of the cylindrical rigid body. With the body disposed, at least the inner cylindrical rigid body and the thermoplastic resin cylindrical body are heated, and this heating softens the thermoplastic resin cylindrical body and expands the inner cylindrical rigid body. The outer peripheral surface of the cylindrical body of the thermoplastic resin is pressed against the inner peripheral surface of the outer cylindrical rigid body, and the inner peripheral surface of the outer cylindrical rigid body is heated to the outer peripheral surface of the cylindrical body of the thermoplastic resin. There is a method of pressure transfer (hereinafter referred to as a double mold forming method), but it is not limited thereto.
[0083]
When pressure from the inside is applied to the entire cylindrical body of the thermoplastic resin by this method, it is considered that the resin on the end side flows out to the outside where no pressure is applied, so that the film thickness at the end becomes thin. The melting characteristic of the resin required at this time is that the viscosity at the outflow start temperature + 5 ° C. is 1.2 to 50 times the viscosity at the outflow start temperature + 15 ° C. of the flow tester. If it is less than 1.2 times, the resin does not flow easily and the end film thickness does not become thin, and the end film thickness becomes larger than 95% with respect to the belt center film thickness. On the other hand, if it is larger than 50 times, the end film thickness becomes too thin and becomes less than 60% with respect to the belt center film thickness.
[0084]
The volume resistance measuring method according to the present invention will be described below.
[0085]
<Volume resistance measurement method>
The measuring device uses an ultra-high resistance meter R8340A (manufactured by Advantest) for the resistance meter, and the sample box TR42 (manufactured by Advantest) for the sample box, but the main electrode has a diameter of 25 mm and the guard ring electrode has an inner diameter. The outer diameter is 41 mm and the outer diameter is 49 mm.
[0086]
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. On one side of the cut-out circular piece, an electrode is provided on the entire surface by a Pt—Pd vapor deposition film, and on the other side, a main electrode having a diameter of 25 mm and a guard electrode having an inner diameter of 38 mm and an outer diameter of 50 mm are provided by a Pt—Pd vapor deposition film. 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.
[0087]
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 an applied voltage of 100 V.
[0088]
【Example】
  referenceExample 1
  <Preparation of intermediate transfer belt>
100 parts of PVDF
  Outflow start temperature + viscosity at 5 ° C. = 2 × 10^FourPa · s
  Outflow start temperature + viscosity at 15 ° C. = 7 × 10^ThreePa · s
Polyetheresteramide resin 10.5 parts
  Outflow start temperature + viscosity at 5 ° C. = 1 × 10^FivePa · s
  Outflow start temperature + viscosity at 15 ° C. = 2 × 10^ThreePa · s
  This material was melted and kneaded at 210 ° C. by a biaxial extruder to mix each material, extruded with a strand having a diameter of about 2 mm, and cut into pellets. This was designated as molding raw material 1. The viscosity of the molding raw material 1 at the outflow start temperature + 5 ° C. is 2 × 10^FourPa · s, outflow start temperature + viscosity at 15 ° C is 6 x 10^ThreePa · s. The viscosity at the outflow start temperature + 5 ° C. was 3.3 times the viscosity at the outflow start temperature + 15 ° C., and was in the range of 1.2 to 50 times.
[0089]
Next, the forming raw material 1 was put into the hopper 102 of the single-screw extruder 100 shown in FIG. 3, and the melt was formed by adjusting the set temperature to 200 ° C. and extruding. The melt was subsequently guided to a cylindrical single layer spiral die 103 having a die diameter of 100 mm and a die gap width of 1200 μm. At this time, the discharge speed of the melt discharged from the tip of the die was 1 m / min. Furthermore, by blowing air from the air introduction path 104 to expand and expand, while forming while taking up at a take-up speed of 5 m / min, by continuously cutting the tubular film every 230 mm in the vertical direction toward the longitudinal direction. A belt. The extrusion molding ratio at this time was 1.4. As a result, the final shape dimensions were 140 mm in diameter, 150 μm in thickness, and 230 mm in belt width, and an intermediate transfer belt was obtained. This was designated as an intermediate transfer belt (1).
[0090]
Further, when the intermediate transfer belt (1) was left in an environment of 23 ° C./55% for 1 day and measured for resistance, the volume resistance value was 6.5E + 11 Ωcm.
[0091]
The intermediate transfer belt (1) has an average wavelength (Sm value) of 10.8 mm, an average wave height (Rz) of 26 μm, and surface waviness having an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction. The average wave height of the undulation was 30 μm or less, the average value of the end film thickness was 150 μm, and a belt that was the same as the central film thickness was obtained.
[0092]
  <Production of cartridge>
  Next bookreferenceThe process cartridge used in the example will be described.
[0093]
FIG. 5 shows a process cartridge constituted by connecting an electrophotographic photosensitive member unit having an electrophotographic photosensitive member and an intermediate transfer belt unit having an intermediate transfer belt.
[0094]
6 and 7 show an intermediate transfer belt unit and an electrophotographic photosensitive member unit, respectively.
[0095]
The frame structure is roughly divided into two.
[0096]
An electrophotographic photosensitive member frame 59 having an integral configuration with the waste toner container 52 shown in FIG. 5 is combined with an electrophotographic photosensitive member 1, a charging roller 2, a cleaning blade 53, a screw 54, and a drum shutter 55 as main components. In the photographic photosensitive unit 50 and the intermediate transfer belt frame 45 shown in FIG. 6, the intermediate transfer belt 5 is mounted on the driving roller 8 ′ and the driven roller 12 ′ and is opposed to the electrophotographic photosensitive member 1. It is divided into an intermediate transfer belt unit 51 in which a primary transfer roller 58 is disposed on the inner side and a charge applying means (intermediate transfer belt cleaning roller) 9 ′ is also disposed on the driving roller 8 ′.
[0097]
In these two units, protrusions 71 provided at both left and right ends of the electrophotographic photosensitive member frame 59 are inserted into positioning holes 72 provided in the intermediate transfer belt frame 45, respectively. A hook 73 of a snap-fit type hook provided at the center in the width direction is fitted into and connected to a lock hole 74 of the intermediate transfer frame 45.
[0098]
Here, the positioning hole 72 and the lock hole 74 provided in the intermediate transfer frame 45 are formed as holes larger by a predetermined amount than the projection 71 and the hook claw 73 provided in the electrophotographic photosensitive member frame 59. In addition, a predetermined amount of relative position movement is possible between the electrophotographic photosensitive member unit 50 and the intermediate transfer belt unit 51. Further, the positioning hole 72 is provided with a tapered portion 72a so that it can be easily attached and detached.
[0099]
In FIG. 7, the hook claw 73 of the electrophotographic photosensitive member unit 50 is pushed to remove it from the lock hole 74 of the intermediate transfer belt unit 51, and the electrophotographic photosensitive member unit 50 is rotated. As shown in FIGS. The photoconductor unit 50 and the intermediate transfer belt unit 51 can be divided.
[0100]
When connecting, contrary to the above, the protrusion 71 of the electrophotographic photosensitive member unit 50 is inserted into the positioning hole 72 of the intermediate transfer belt unit 51 and rotated in the opposite direction to that of the removal so that the hook claw 73 is moved. By pushing into the lock hole 74, the two units are connected.
[0101]
FIG. 8 shows a state when the process cartridge of the present invention is attached to and detached from the electrophotographic apparatus. By simply opening the upper cover 60 of the main body of the electrophotographic apparatus, the process cartridge can be easily attached and detached as in the case of a conventional black and white laser beam printer, and maintenance such as jam processing and process cartridge replacement can be easily performed.
[0102]
A photosensitive drum and an intermediate transfer belt (1) having the following conditions were assembled to the above cartridge.
Radius r of photosensitive drum: 23.5mm
Intermediate transfer belt thickness: 150 μm
Primary transfer roller diameter: 13 mm
Spring pressure of primary transfer roller: 3N
Spring pressure of tension roller: 20N
Tension roller slide amount: 2.5mm
Tension roller diameter: 28 mm
Drive roller diameter: 28mm
This cartridge was designated as cartridge (1).
[0103]
<Image confirmation>
The cartridge (1) is allowed to stand for 12 hours in an environment of 23 ° C./55%, and then set in the electrophotographic apparatus shown in FIG.²A full color image print test was performed on paper. The developing device used here was a 600 dpi digital laser system. When the obtained image was visually evaluated, the intermediate transfer belt had surface waviness with an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction, and the average wave height of the surface waviness was 30 μm or less. Therefore, no image unevenness was observed, and a good full color image having no problem was obtained. Further, since the average wave height of the surface waviness was 30 μm or less, no cleaning unevenness was generated.
[0104]
Furthermore, the transfer efficiency was defined as follows and the transfer efficiency was measured.
[0105]
Primary transfer efficiency (transfer efficiency from photosensitive drum to intermediate transfer belt) =
Image density on intermediate transfer belt / (Remaining transfer image density on photosensitive drum + Image density on intermediate transfer belt)
As a measurement result, a primary transfer efficiency of 95% was obtained.
[0106]
When 100,000 full-color images were output using this cartridge (1) and the belt was confirmed, the belt was free from cracks and tears and had good durability. Further durability was observed, but the end of the belt cracked at the 120,000th sheet, so there was no problem on the image, but the durability was stopped. The durability of this belt was 120,000.
[0107]
Thus, it was confirmed that the cartridge (1) has good performance and long life.
[0108]
Further, a cartridge identical to this cartridge was produced and left to stand for one month in an environment of 40 ° C. and 95% RH, and an image was output. However, no vertical wrinkles due to waviness occurred and a good image was obtained. .
[0109]
  Example1
  <Preparation of intermediate transfer belt>
  the material isreferenceSame as Example 1.
[0110]
This material was melted and kneaded at 210 ° C. by a biaxial extruder to mix each material, extruded with a strand having a diameter of about 2 mm, and cut into pellets. This was designated as molding raw material 1. Next, in the molding apparatus of FIG. 3, the molding die 103 was a single-layer annular die, and a die slit having a diameter of 20 mm was used. The die slit was 0.8 mm. The raw material for molding 1 sufficiently heated and dried was put into a material hopper 102 of this molding apparatus, heated and melted, and extruded from a die at 210 ° C. in a cylindrical shape. An external cooling ring 105 was installed around the die, and air was blown from the periphery to the extruded cylindrical film to perform cooling. In addition, air was blown into the extruded tubular film from the air introduction path 104 and expanded to a diameter of 140 mm, and then continuously taken up at a constant speed by a take-up device. The introduction of air was stopped when the diameter reached the desired value. Furthermore, the cylindrical film was cut with the cutting device 108 following the pinch roller. After the thickness was stabilized, the tubular film 1 was formed by cutting with a length of 310 mm.
[0111]
About this cylindrical film 1, size and surface smoothness adjustment and removal of a crease | fold were performed using a set of cylindrical type | molds which consist of a metal from which a thermal expansion coefficient differs. The tubular film 1 was put on an inner mold having a high coefficient of thermal expansion, and the inner mold was inserted into an outer mold having a smooth inner surface and heated at 190 ° C. for 20 minutes. After cooling, it was removed from the cylinder and the end was cut to prepare an intermediate transfer belt (2) having a diameter of 140 mm.
[0112]
Further, when the intermediate transfer belt (2) was left in an environment of 23 ° C./55% for 1 day and resistance was measured, the volume resistance value was 6.0E + 11 Ωcm.
[0113]
This intermediate transfer belt has an average wavelength (Sm value) of 0.2 mm, an average wave height (Rz) of 0.8 μm, and a surface waviness having an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction. A belt having an average wave height of 30 μm or less, an average thickness of the end film thickness of 120 μm, and 80% of the center film thickness was obtained.
[0114]
  <Production of cartridge>
  Other than using the intermediate transfer belt (2)referenceA cartridge (2) was produced in the same manner as in Example 1.
[0115]
<Image confirmation>
The cartridge (2) is allowed to stand for 12 hours in an environment of 23 ° C./55% and then set in the electrophotographic apparatus of FIG.²A full color image print test was performed on paper. The developing device used here was a 600 dpi digital laser system. When the obtained image was visually evaluated, the intermediate transfer belt had surface waviness with an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction, and the average wave height of the surface waviness was 30 μm or less. Therefore, no image unevenness was observed, and a good full color image having no problem was obtained. Further, since the average wave height of the surface waviness was 30 μm or less, no cleaning unevenness was generated. Further, a primary transfer efficiency of 95% was obtained.
[0116]
Using this cartridge (2), 100,000 full-color images were output and the intermediate transfer belt (2) was confirmed. As a result, the belt was not cracked or cracked, and the durability was good. Further durability, even at the 120,000th sheet, there was no crack at the end of the belt, and it was further durable up to 150,000 sheets, but there was no crack at the end of the belt, and it had higher durability than Example 1. all right. Thus, it was confirmed that the cartridge (2) has good performance and long life.
[0117]
Further, a cartridge identical to this cartridge was produced and left to stand for one month in an environment of 40 ° C. and 95% RH, and an image was output. However, no vertical wrinkles due to waviness occurred and a good image was obtained. .
[0118]
  Example2
  <Preparation of intermediate transfer belt>
100 parts of PVDF
  Outflow start temperature + viscosity at 5 ° C. = 2 × 10^FourPa · s
  Outflow start temperature + viscosity at 15 ° C. = 1 × 10^ThreePa · s
Polyetheresteramide resin 10.5 parts
  Outflow start temperature + viscosity at 5 ° C. = 1 × 10^FivePa · s
  Outflow start temperature + viscosity at 15 ° C. = 2 × 10^ThreePa · s
  This material was melted and kneaded at 210 ° C. by a biaxial extruder to mix each material, extruded with a strand having a diameter of about 2 mm, and cut into pellets. This was designated as forming raw material 2. The viscosity of the molding raw material 2 when the outflow start temperature + 5 ° C. is 4 × 10^FourThe viscosity at Pa · s, outflow start temperature + 15 ° C is 1 × 10^ThreeThe viscosity at the outflow start temperature + 5 ° C. was 40 times the viscosity at the outflow start temperature + 15 ° C., and was in the range of 1.2 to 50 times.
[0119]
Next, in the molding apparatus of FIG. 3, the molding die 103 was a single-layer annular die, and the die slit having a diameter of 100 mm was used. The die slit was 0.8 mm. The molding raw material 2 sufficiently heated and dried was put into the material hopper 102 of this molding apparatus, heated and melted, and extruded into a cylindrical shape at 210 ° C. from the die. An external cooling ring 105 was installed around the die, and air was blown from the periphery to the extruded cylindrical film to perform cooling. In addition, air was blown into the extruded tubular film from the air introduction path 104 and expanded to a diameter of 140 mm, and then continuously taken up at a constant speed by a take-up device. The introduction of air was stopped when the diameter reached the desired value. Furthermore, the cylindrical film was cut with the cutting device 108 following the pinch roller. After the thickness was stabilized, the tubular film 2 was formed by cutting with a length of 310 mm.
[0120]
About this cylindrical film 2, adjustment of size and surface smoothness, and the removal of the crease | fold were performed using a set of cylindrical shape which consists of a metal from which a thermal expansion coefficient differs. The tubular film 2 was put on an inner mold having a high coefficient of thermal expansion, and the inner mold was inserted into an outer mold whose inner surface was processed smoothly and heated at 190 ° C. for 20 minutes. After cooling, it was removed from the cylinder and the end was cut to prepare an intermediate transfer belt (3) having a diameter of 140 mm.
[0121]
Further, when the intermediate transfer belt (3) was left in an environment of 23 ° C./55% for 1 day and resistance was measured, the volume resistance value was 8.0E + 11 Ωcm.
[0122]
The intermediate transfer belt (3) has an average wavelength (Sm value) of 0.15 mm, an average wave height (Rz) of 0.5 μm, and a surface undulation having an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction. The belt having an average wave height of the surface waviness of 30 μm or less, an average value of the end film thickness of 100 μm, and an end film thickness of 67% with respect to the central film thickness was obtained.
[0123]
  <Production of cartridge>
  Other than using the intermediate transfer belt (3)referenceA cartridge (3) was produced in the same manner as in Example 1.
[0124]
<Image confirmation>
The cartridge (3) is allowed to stand for 12 hours in an environment of 23 ° C./55% and then set in the electrophotographic apparatus of FIG.²A full color image print test was performed on paper. The developing device used here was a 600 dpi digital laser system. When the obtained image was visually evaluated, the intermediate transfer belt had surface waviness with an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction, and the average wave height of the surface waviness was 30 μm or less. Therefore, no image unevenness was observed, and a good full color image having no problem was obtained. Further, since the average wave height of the surface waviness was 30 μm or less, no cleaning unevenness was generated. Further, a primary transfer efficiency of 95% was obtained.
[0125]
Using this cartridge (3), 100,000 full-color images were output and the intermediate transfer belt (3) was confirmed. As a result, the belt was not cracked or cracked, and the durability was good. Further durability, even at the 120,000th sheet, there was no crack at the end of the belt, and it was further durable up to 150,000 sheets, but there was no crack at the end of the belt, and it had higher durability than Example 1. all right. Thus, it was confirmed that the cartridge (3) has good performance and long life.
[0126]
Also, the same cartridge as this cartridge (3) was produced and left to stand for one month in an environment of 40 ° C. and 95% RH, and the image was output, but a good image was obtained without causing vertical wrinkles due to waviness. It was.
[0127]
  Example3
  <Preparation of transfer belt>
100 parts of polycarbonate resin
  Outflow start temperature + Viscosity at 5 ° C 4 x 10^FourPa · s
  Outflow start temperature + Viscosity at 15 ° C 1 x 10^FourPa · s
Conductive carbon 8 parts
  This material was melted and kneaded at 280 ° C. by a biaxial extruder to mix each material, and extruded and cut with a strand having a diameter of about 2 mm to form a pellet. This was designated as a raw material 3 for molding. The viscosity of the molding raw material 3 when the outflow start temperature + 5 ° C. is 6 × 10^FourThe viscosity at Pa · s, outflow start temperature + 15 ° C is 4 × 10^FourThe viscosity at the outflow start temperature + 5 ° C. was 1.5 times the viscosity at the outflow start temperature + 15 ° C., which was in the range of 1.2 to 50 times.
[0128]
Next, in the molding apparatus of FIG. 3, the molding die 103 was a single-layer annular die, and a die slit having a diameter of 200 mm was used. The die slit was 0.8 mm.
[0129]
At this time, the discharge speed of the melt discharged from the tip of the die was 1 m / min. Further, air is blown and expanded through the air introduction passage 104, and the tubular film is continuously cut in the vertical direction toward the longitudinal direction every 340 mm while forming while taking up at a take-up speed of 4.5 m / min. A tubular film was obtained. This tubular film was designated as tubular film 3. The extrusion molding ratio at this time was 1.55. Moreover, the diameter of the cylindrical film 3 was 355 mm, and the center film thickness was 100 micrometers.
[0130]
About this cylindrical film 3, adjustment of size and surface smoothness, and the removal of the crease | fold were performed using a set of cylindrical type | molds which consist of a metal from which a thermal expansion coefficient differs. The cylindrical film 3 was put on an inner mold having a high coefficient of thermal expansion, and the inner mold was inserted into an outer mold having a smooth inner surface and heated at 260 ° C. for 20 minutes. After cooling, it was removed from the cylinder and the end portion was cut to prepare a transfer belt (1) having a diameter of 355 mm, a belt center film thickness of 100 μm, and a belt width of 310 mm.
[0131]
Further, when the transfer belt (1) was left in an environment of 23 ° C./55% for 1 day and subjected to resistance measurement, the volume resistance value was 2E + 12 Ωcm.
[0132]
The transfer belt (1) has an average wavelength (Sm value) of 0.12 mm, an average wave height (Rz) of 1.2 μm, and a surface undulation having an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction. The average wave height of the surface waviness was 30 μm or less, the average value of the end film thickness was 93 μm, and a belt that was 93% of the center film thickness was obtained.
[0133]
<Image confirmation>
The transfer belt (1) is allowed to stand for 12 hours in an environment of 23 ° C./55% and then set in the electrophotographic apparatus shown in FIG.²A full color image print test was performed on paper. The developing device used here was a 600 dpi digital laser system. When the obtained image was visually evaluated, the transfer belt had surface waviness with an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction, and the average wave height of the surface waviness was 30 μm or less. No image unevenness was observed, and a good full color image having no problem was obtained. Further, since the average wave height of the surface waviness was 30 μm or less, no cleaning unevenness was generated.
[0134]
Using this transfer belt (1), 100,000 full-color images were output and the transfer belt (1) was confirmed. As a result, the belt was not cracked or cracked, and the durability was good. As a result of further durability, it was found that even at the 120,000th sheet, there was no crack at the end of the belt, and further durability was achieved up to 150,000 sheets, but no crack was seen at the end of the belt, and it was found to have high durability. Thus, it was confirmed that the transfer belt (1) has good performance and long life.
[0135]
Comparative Example 1
<Preparation of intermediate transfer belt>
100 parts of PVDF
Outflow start temperature + viscosity at 5 ° C. = 5 × 10^FourPa · s
Outflow start temperature + viscosity at 15 ° C. = 1 × 10^ThreePa · s
Polyetheresteramide resin 10.5 parts
Outflow start temperature + viscosity at 5 ° C. = 1 × 10^FivePa · s
Outflow start temperature + viscosity at 15 ° C. = 2 × 10^FourPa · s
This material was melted and kneaded at 210 ° C. by a biaxial extruder to mix each material, extruded with a strand having a diameter of about 2 mm, and cut into pellets. This was used as a raw material 4 for molding. The viscosity of the molding raw material 4 at the time of starting outflow + 5 ° C. is 6.5 × 10^FourThe viscosity at Pa · s, outflow start temperature + 15 ° C is 1 × 10^ThreeThe viscosity at the outflow start temperature + 5 ° C. was 65 times that of the viscosity at the outflow start temperature + 15 ° C., which was outside the range of 1.2 to 50 times.
[0136]
Next, the raw material 4 for molding was put into the hopper 102 of the single-screw extruder 100 shown in FIG. 3, and the melt was made by adjusting the set temperature to 200 ° C. and extruding. The melt was subsequently guided to a cylindrical single layer spiral die 103 having a die diameter of 30 mm and a die gap width of 1000 μm. At this time, the discharge speed of the melt discharged from the tip of the die was 1 m / min. Furthermore, by blowing air from the air introduction path 104 to expand and expand, while forming while taking up at a take-up speed of 5 m / min, by continuously cutting the tubular film every 230 mm in the vertical direction toward the longitudinal direction. A belt. The extrusion molding ratio at this time was 4.67. For this reason, the molding stability was poor. As a result, the final shape dimensions were 140 mm in diameter, 150 μm in thickness, and 230 mm in belt width, and an intermediate transfer belt was obtained. This was designated as an intermediate transfer belt (4).
[0137]
The intermediate transfer belt (4) has an average wavelength (Sm value) of 10 mm, an average wave height (Rz) of 35 μm, and a surface undulation with an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction. A belt having an average wave height greater than 30 μm, an average value of the end film thickness of 150 μm, and 100% of the center film thickness was obtained.
[0138]
  <Production of cartridge>
  Other than using the intermediate transfer belt (4)referenceA cartridge (4) was produced in the same manner as in Example 1.
[0139]
<Image confirmation>
The cartridge (4) is allowed to stand for 12 hours in an environment of 23 ° C./55% and then set in the electrophotographic apparatus of FIG.²A full color image print test was performed on paper. The developing device used here was a 600 dpi digital laser system. When the obtained image was visually evaluated, the intermediate transfer belt had surface waviness with an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction, and the average wave height of the surface waviness was larger than 30 μm. Image unevenness due to undulation occurred. Further, since the average wave height of the surface waviness was larger than 30 μm, the concave portion of the waviness was not sufficiently cleaned, and cleaning unevenness occurred. Further, the primary transfer efficiency was 80% due to transfer unevenness.
[0140]
When 5000 full-color images were output using this cartridge (4), a tear occurred in the intermediate transfer belt, and image output could not be continued.
[0141]
In addition, the same cartridge as this cartridge (4) was manufactured and left to stand for one month in an environment of 40 ° C. and 95% RH, and an image was output. However, vertical wrinkles due to waviness occurred, and images due to vertical wrinkles occurred. Unevenness occurred.
[0142]
Comparative Example 2
<Preparation of transfer belt>
100 parts of polycarbonate resin
Outflow start temperature + viscosity at 5 ° C. = 4 × 10^FourPa · s
Outflow start temperature + viscosity at 15 ° C. = 1 × 10^FourPa · s
Conductive carbon 8 parts
Kaolin clay 30 parts
This material was melted and kneaded at 280 ° C. by a biaxial extruder to mix each material, and extruded and cut with a strand having a diameter of about 2 mm to form a pellet. This was designated as a molding material 5. The viscosity of the raw material 5 for molding at the outflow start temperature + 5 ° C. is 6 × 10^FourThe viscosity at Pa · s, outflow start temperature + 15 ° C. is 5.5 × 10^FourThe viscosity at the outflow start temperature + 5 ° C. was 1.09 times the viscosity at the outflow start temperature + 15 ° C., which was outside the range of 1.2 to 50 times.
[0143]
Next, in the molding apparatus of FIG. 3, the molding die 103 was a single-layer annular die, and a die slit having a diameter of 200 mm was used. The die slit was 0.2 mm.
[0144]
At this time, the discharge speed of the melt discharged from the tip of the die was 1 m / min. Further, air is blown and expanded through the air introduction path 104, and the tubular film is continuously cut in the vertical direction in the longitudinal direction every 310 mm while forming at a take-up speed of 4.5 m / min. A tubular film was obtained. The extrusion molding ratio at this time was 1.55. As a result, the final shape dimensions were 355 mm in diameter, 150 μm in thickness, and 310 mm in belt width, and a transfer belt was obtained. This was designated as a transfer belt (2).
[0145]
This transfer belt (2) has an average wavelength (Sm value) of 5 mm, an average wave height (Rz) of 40 μm, and surface waviness having an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction. A belt having a wave height larger than 30 μm, an average value of end film thickness of 150 μm, and 100% of the center film thickness was obtained.
[0146]
<Image confirmation>
The transfer belt (2) is allowed to stand for 12 hours in an environment of 23 ° C./55% and then set in the electrophotographic apparatus shown in FIG.²A full color image print test was performed on paper. The developing device used here was a 600 dpi digital laser system. When the obtained image was visually evaluated, the transfer belt had surface waviness with an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction, and the average wave height of the surface waviness was larger than 30 μm. It was a full-color image in which image unevenness due to transfer unevenness occurred. Further, since the average wave height of the surface waviness was larger than 30 μm, the back surface of the transfer material was soiled due to uneven cleaning.
[0147]
When 4000 full-color images were output using this transfer belt (2), a tear occurred in the transfer belt, and image output could not be continued.
[0148]
Comparative Example 3
<Preparation of intermediate transfer belt>
The material is the same as Comparative Example 1.
[0149]
This material was melted and kneaded at 210 ° C. by a biaxial extruder to mix each material, extruded with a strand having a diameter of about 2 mm, and cut into pellets. This was used as a raw material 4 for molding. Next, in the molding apparatus of FIG. 3, the molding die 103 was a single-layer annular die, and a die slit having a diameter of 20 mm was used. The die slit was 0.8 mm. The molding raw material 4 sufficiently heated and dried was put into the material hopper 102 of this molding apparatus, heated and melted, and extruded into a cylindrical shape at 210 ° C. from the die. An external cooling ring 105 was installed around the die, and air was blown from the periphery to the extruded cylindrical film to perform cooling. In addition, air was blown into the extruded tubular film from the air introduction path 104 and expanded to a diameter of 140 mm, and then continuously taken up at a constant speed by a take-up device. The introduction of air was stopped when the diameter reached the desired value. Furthermore, the cylindrical film was cut with the cutting device 108 following the pinch roller. After the thickness was stabilized, the tubular film 4 was formed by cutting with a length of 310 mm.
[0150]
About this cylindrical film 4, adjustment of size and surface smoothness, and the removal of the crease | fold were performed using a set of cylindrical shape which consists of a metal from which a thermal expansion coefficient differs. The tubular film 4 was put on an inner mold having a high coefficient of thermal expansion, and the inner mold was inserted into an outer mold having a smooth inner surface and heated at 190 ° C. for 20 minutes. After cooling, it was removed from the cylinder and the end was cut to produce an intermediate transfer belt (5) having a diameter of 140 mm.
[0151]
The intermediate transfer belt has an average wavelength (Sm value) of 0.2 mm, an average wave height (Rz) of 1.5 μm, and a surface undulation having an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction. A belt having an average wave height of 30 μm or less, an average value of the end film thickness of 70 μm, and 47% of the center film thickness was obtained.
[0152]
  <Production of cartridge>
  Other than using the intermediate transfer belt (5)referenceA cartridge (5) was produced in the same manner as in Example 1.
[0153]
<Image confirmation>
The cartridge (5) is allowed to stand for 12 hours in an environment of 23 ° C./55% and then set in the electrophotographic apparatus of FIG.²A full color image print test was performed on paper. The developing device used here was a 600 dpi digital laser system. When the obtained image was visually evaluated, it had surface waviness with an average wavelength of 0.1 mm or more and less than 20 mm in the belt circumferential direction, and the average wave height of the surface waviness was 30 μm or less. Thus, a good full color image without any problem was obtained. Further, since the average wave height of the surface waviness was 30 μm or less, no cleaning unevenness was generated. Further, a primary transfer efficiency of 95% was obtained.
[0154]
At the time when 5000 full-color images were output using this cartridge (5), the intermediate transfer belt was stretched. This is probably because the end film thickness was too thin. As a result, the belt was not tensioned and could not be driven, so image output could not be continued.
[0155]
In addition, a cartridge identical to this cartridge was produced, and the image was output by leaving it in an environment of 40 ° C. and 95% RH for one month. However, wrinkles occurred at the edges and the image unevenness was caused at the edges. Occurred.
[0156]
【The invention's effect】
As described above, according to the present invention, there is no unevenness in the image, and a highly durable electrophotographic belt achieves a low running cost, a miniaturized main body, high image quality, and simplified maintenance by enhancing the durability of the cartridge. It can be done.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an outline of an example of an image forming apparatus using an intermediate transfer belt of the present invention.
FIG. 2 is a diagram showing an outline of an example of an image forming apparatus using the transfer belt of the present invention.
FIG. 3 is a schematic view of an example of a molding apparatus when the intermediate transfer belt of the present invention has one layer.
FIG. 4 is a schematic view of an example of a molding apparatus when the intermediate transfer belt of the present invention has two layers.
FIG. 5 is an explanatory diagram of a process cartridge.
FIG. 6 is an explanatory diagram of an intermediate transfer unit.
FIG. 7 is an explanatory diagram of an electrophotographic photosensitive member unit.
FIG. 8 is an explanatory diagram of a process cartridge attachment / detachment configuration.
[Explanation of symbols]
1 Photosensitive drum
2 Primary charger
3 Image exposure means
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
20 Intermediate transfer belt
30, 31, 33 Bias power supply
41 yellow toner
42 Magenta Toner
43 Cyan Toner
44 Black Toner
100, 101 Extruder
102 hopper
103 ring die
104 Air introduction path
105 External cooling ring
106 Stabilizer
107 Pinch roller
108 cutting equipment
110 Cylindrical film
P transfer material

Claims (9)

It is obtained by melting and extruding a thermoplastic resin mixture in which the viscosity at the flow tester's outflow start temperature + 5 ° C is 1.2 to 50 times the viscosity at the flow tester's outflow start temperature + 15 ° C. The diameter of the tubular film is controlled by injecting or sucking gas into the tubular film to adjust the internal volume, and a member that supports the tubular film until the tubular film is cooled and solidified. Forming the cylindrical film from the annular die without using it, and then manufacturing the cylindrical body of the thermoplastic resin mixture by a method of cutting;
For electrophotography made of a thermoplastic resin mixture used in an image forming apparatus , which is produced by a process of heating and expanding and pressing the cylindrical body inside a cylindrical rigid body having a diameter larger than the diameter of the cylindrical body A belt ,
Electrophotographic belt is a belt circumferential direction to have a surface waviness of wavelengths less than the average 0.1mm than 20 mm, the average height of the surface undulations Ri der less 30 [mu] m, and the longitudinal direction of the at least one side edge of the belt An electrophotographic belt, wherein the partial film thickness is 60% or more and 95% or less with respect to the belt center film thickness . The thickness of the formed tubular film may electrophotographic belt according to 請 Motomeko 1 Ru der 1/3 annular die gap. The molded diameter of the tubular film is 50% or more of the annular die diameter, electrophotographic belt according to Der Ru請 Motomeko 1 400% or less. A primary transfer step in which the electrostatic latent image formed on the electrophotographic photosensitive member is visualized with a developer, and the obtained image is transferred to an intermediate transfer belt, and the image transferred to the intermediate transfer belt is further transferred. In an electrophotographic photosensitive member-intermediate transfer belt integrated cartridge configured to be detachable from an image forming apparatus main body having a secondary transfer process for transferring to a material,
Intermediate transfer belt, an electrophotographic photoreceptor, characterized in that an electrophotographic belt according to any one of claims 1 to 3 - the intermediate transfer belt integrated cartridge. It said electrophotographic photosensitive member is an electrophotographic photosensitive member according to the electrophotographic photosensitive drum der Ru請 Motomeko 4 consisting of a rigid diameter 60 mm - intermediate transfer belt integrated cartridge. Said electrophotographic photosensitive member - the intermediate transfer belt integrated cartridge, the back said on said electrophotographic photosensitive member by the toner on the intermediate transfer belt imparting toner polarity and opposite polarity charges at the time of primary transfer intermediate the electrophotographic photosensitive member according to the cleaning apparatus of the cleaning system for cleaning the transfer belt to claim 4 in which integrated with the cartridge - the intermediate transfer belt integrated cartridge. It said electrophotographic photosensitive member - the intermediate transfer belt integrated cartridge is a separable and an intermediate transfer belt unit having the intermediate transfer belt and the electrophotographic photosensitive member unit having the electrophotographic photosensitive member, the electrophotographic photosensitive member the electrophotographic photosensitive member according to 請 Motomeko 4 that have a connecting means for connecting the units and the intermediate transfer belt unit - the intermediate transfer belt integrated cartridge. A primary transfer step in which the electrostatic latent image formed on the electrophotographic photosensitive member is visualized with a developer, and the obtained image is transferred to an intermediate transfer belt, and the image transferred to the intermediate transfer belt is further transferred. In an image forming apparatus using an image forming apparatus main body having a secondary transfer step of transferring to a material,
An image forming apparatus , wherein the intermediate transfer belt is the electrophotographic belt according to claim 1 . It has surface waviness with a wavelength of 0.1 mm or more and less than 20 mm on the average in the belt circumferential direction, the average wave height of the surface waviness is 30 μm or less, and the film thickness at least at one end in the longitudinal direction of the belt is the belt center film thickness. 60% or more and 95% or less of the electrophotographic belt made of a thermoplastic resin used in an image forming apparatus,
A thermoplastic resin mixture whose viscosity at the flow tester outflow start temperature + 5 ° C is 1.2 to 50 times higher than the viscosity at the flow tester outflow start temperature + 15 ° C is dissolved from the annular die. The diameter of the tubular film is controlled by injecting or sucking gas into the tubular film obtained by melt-extrusion to adjust the internal volume, and the tubular film is cooled until solidified. Forming a cylindrical body of the thermoplastic resin mixture by a method of forming the cylindrical film from the annular die without using a member for supporting
Heating and pressing the cylindrical body inside a cylindrical rigid body having a diameter larger than the diameter of the cylindrical body; and
A method for producing an electrophotographic belt, comprising:

Images