JP4735244B2 - Semiconductive rubber belt, method for manufacturing the same, and image forming apparatus - Google Patents

Description

  The present invention relates to a semiconductive rubber belt used in an electrophotographic copying machine, a printer, and the like, a manufacturing method thereof, and an image forming apparatus using the same.

  An image forming apparatus using an electrophotographic system forms a uniform charge (charge) on the surface of an electrostatic latent image carrier (photosensitive member), and forms an electrostatic latent image with a laser that modulates an image signal. Then, the electrostatic latent image is developed with charged toner to form a toner image. The toner image can be transferred directly via an intermediate transfer member or electrostatically onto a recording medium to obtain a desired transfer image.

  In the transfer system using the intermediate transfer member, there has been reported a case in which a woven fiber is used for an elastic rubber base material as a measure for improving curry registration (permanent elongation) (for example, see Patent Document 1). However, this method is complicated and cannot be easily manufactured. Another problem is that the fibers inhibit the uniformity of the resistance value.

On the other hand, in order to improve the variation in the resistance of the belt material with time and the unevenness of the belt resistance value, a semiconductive resin layer having a large Young's modulus is bonded to the back surface of the rubber base material to improve the permanent elongation and the resistance unevenness. A method has been proposed (see, for example, Patent Document 2).
However, in the above belt structure, the elastic force of the rubber is lost, the self-walk correction effect of the rubber itself is hindered, and it is necessary to provide a tension mechanism other than the belt or a rib for preventing the walk at the end of the belt. The problem of increased manufacturing process occurs.
JP 10-39642 A JP 2003-122138 A

An object of the present invention is to solve the conventional problems and achieve the following objects. That is,
An object of the present invention is to provide a semiconductive rubber belt in which a decrease in tension over time is suppressed, a production method capable of easily producing such a semiconductive rubber belt, and image formation using the semiconductive rubber belt. To provide an apparatus.

<1> When the biaxial stretching roll is stretched 5% under the conditions of 25 ° C. ± 2 ° C. and 55% ± 5% RH, the stretching force attenuation rate represented by the following formula (1) is less than 50%. A semiconductive rubber belt characterized by being in a range.
Tensile force damping rate (%) = {(initial tension force−predicted tension value after two years) / initial tension force} × 100 (1)
(Here, the predicted tension force after two years is a value calculated from a logarithmic approximation obtained from the result of measuring the tension force for 30 days under the above conditions.)
<2> The semiconductive rubber belt according to <1>, further including an ion conductive and / or electronic conductive agent.
<3> The semiconductive rubber belt according to <1> or <2>, wherein the surface has one or more layers.

<4> An image forming apparatus comprising the semiconductive rubber belt according to any one of <1> to <3>.
<5> The image forming apparatus according to <4>, wherein the semiconductive rubber belt is provided as an intermediate transfer belt and / or a paper transport belt.

<6> A method for producing a semiconductive rubber belt, comprising a heating step of performing a heat treatment in a state where the semiconductive rubber belt is stretched by 2% or more after the semiconductive rubber belt is formed.
<7> The method for producing a semiconductive rubber belt according to <6>, wherein the heating step is performed after forming one or more layers on the surface of the semiconductive rubber belt.

  According to the present invention, a semiconductive rubber belt in which a decrease in tension over time is suppressed, a manufacturing method capable of easily manufacturing such a semiconductive rubber belt, and image formation using the semiconductive rubber belt An apparatus can be provided.

When the semiconductive rubber belt of the present invention is stretched 5% with a biaxial stretch roll under the conditions of 25 ° C. ± 2 ° C. and 55% ± 5% RH, the tension of the tension expressed by the following formula (1) The rate is less than 50%.
Tensile force damping rate (%) = {(initial tension force−predicted tension value after two years) / initial tension force} × 100 (1)
(Here, the predicted tension force after two years is a value calculated from a logarithmic approximation obtained from the result of measuring the tension force for 30 days under the above conditions.)
In the semiconductive rubber belt of the present invention, “semiconductive” means that the volume resistivity of the belt is in the range of 10 ³ to 10 ¹⁰ Ωcm.

  First, a method for measuring the tension force of the semiconductive rubber belt will be described. FIG. 1 conceptually shows a measuring device for measuring the tension force. The measuring apparatus includes a movable stretch roll 110 that can move forward and backward in the left-right direction in FIG. 1 and a fixed stretch roll 112 that does not move forward and backward in that direction. A load cell 114 capable of monitoring stress (stretching force) is disposed in contact. When measuring the tension of the semiconductive rubber belt, the semiconductive rubber belt 116 whose tension is to be measured is stretched between the movable tension roll 110 and the fixed tension roll 112, and the tension is measured by the load cell 114. Get strength information. As for the frequency of tension measurement, collect at least one data per day. It is preferable to collect more detailed data, but the tension changes greatly on the first day, and after the second day, it is sufficient to measure once per day. Further, since the tension force of rubber tends to change depending on the temperature and humidity environment, the temperature and humidity of the measurement chamber are controlled at 25 ° C. ± 2 ° C. and 55% ± 5% RH. The predicted tension force after 2 years is calculated as described above, and the logarithmic approximation formula (details will be described later) is obtained from the data for 30 days from the belt formation and the value after 2 years (730 days) is calculated. To obtain the predicted value.

  Next, the tension (stretching force) is measured for 30 days when the stretching degree of the semiconductive rubber belt is varied from 0%, 2%, and 5% using the tensioning force measuring device shown in FIG. The graph of FIG. 2 shows the relationship of the stress (stretching force) with respect to the passage of time. In FIG. 2, the bottom curve is 0% elongation, the middle curve is 2% elongation, and the top curve is 5% elongation. As can be seen from the graph of FIG. 2, the stress (stretching force) suddenly decreases during the first few days, but thereafter decreases substantially constant. Therefore, the tension force after two years can be estimated approximately.

  Here, the logarithmic approximation formula will be described. In FIG. 2, when the time axis (days) is a logarithmic axis, a linear expression y = ax + b (y: stress (stretching force), x: natural logarithm of days) is obtained by the method of least squares. In addition, a and b are represented by the following formula. In the present invention, the logarithmic approximation formula is obtained from data for 30 days from the belt formation.

  The predicted tension force after 2 years can be determined as the value after 2 years, that is, “ln730”, using the slope a and the y-intercept b obtained from the data for 30 days from the belt formation.

  The semiconductive rubber belt of the present invention satisfies the formula (1) under the above-described conditions and suppresses a decrease in tension over time. When used for an intermediate transfer belt or a conveyor belt of an image forming apparatus, Occurrence of misalignment, poor image magnification, belt walk, etc. can be suppressed, contributing to excellent image quality and transfer performance. The semiconductive rubber belt of the present invention has a tension damping rate based on the above formula (1) of less than 50% when stretched by 5%, but is preferably 40% or less, more preferably 25% or less. The lower limit is 0%, and the closer to 0%, the better. If the tension reduction rate exceeds 50%, a defect may appear in the image obtained by the belt extension. In order to make the tension damping rate at 5% elongation less than 50%, the belt may be heated in a state where it is elongated by 2% or more during firing. Increasing the elongation rate can reduce the tension force damping rate, but if it is too large, secondary obstacles due to molding errors during belt molding, such as variations in belt thickness and in-plane variations in filler, will occur. Therefore, it is preferable to heat at an elongation rate of 10% or less.

  Examples of the belt base material of the semiconductive rubber belt of the present invention include vulcanized rubber and thermoplastic elastomer. Here, as raw material rubber materials, general diene rubbers such as styrene / butadiene rubber (SBR), polyisoprene rubber (IIR), ethylene / propylene / diene rubber (EPDM), polybutadiene rubber (BR), acrylic rubber ( ACM, ANM), etc., but acrylonitrile butadiene rubber is relatively high in rigidity, has a volume resistivity close to semiconductivity, and has good fluidity in the mold. (NBR), hydrogenated NBR, chloroprene rubber (CR), epichlorohydrin rubber (CO, ECO), polyurethane rubber (PUR) and the like are preferable.

  On the other hand, polyester-based, polyurethane-based, styrene-butadiene triblock-based, polyolefin-based, etc. are used as the thermoplastic elastomer. When such a thermoplastic elastomer is used, recycling is possible, which is environmentally preferable. Further, the material of the belt base material is not necessarily one type, and two or more types of materials can be blended. For example, a material obtained by blending chloroprene rubber (CR) and EPDM is used.

  Further, an ion conductive and / or electron conductive conductive agent (conductive filler) or an insulating filler can be added to the belt base material to adjust the volume resistivity of the belt base material.

As the shape of each filler, any shape such as a particulate shape or a long fiber shape may be used. Examples of the conductive filler include carbon black, ketjen black, acetylene black, zinc oxide, potassium titanate, tin oxide, graphite, LiClO ₄ , LiAsF ₆ and other metal salts and various quaternary ammonium salts. In addition, examples of the insulating filler include silica.

  Further, in addition to the above components, the following rubber compounding raw materials can be used for the belt base material. For example, titanium oxide, magnesium oxide, calcium carbonate, calcium sulfate, etc., clay, talc, silica, etc. Examples of colorants include various pigments.

The semiconductive rubber belt of the present invention preferably has one or more layers on the surface. Hereinafter, the layer will be described as a surface layer.
The surface layer formed on the substrate is preferably a toner release layer. As a material used for the toner release layer, a material having a small surface energy such as a fluororesin material and a material including fluororesin particles is used. The surface energy of the surface of the semiconductive belt can be reduced, and dirt is hardly attached to the surface of the semiconductive belt. Contamination of the surface of the toner release semiconductive belt can be effectively prevented.

  Evaporation of the solvent into the air requires no characteristics such as solvent resistance for the base material compared to solvent-based materials by using a material that uses water as the solvent as the toner release layer material Since there is no, there is an advantage such as environmental friendliness. Furthermore, by using a urethane resin as a binder resin material, the urethane resin is composed of a soft segment mainly composed of a long-chain polyol and a hard segment containing an isocyanate compound, so that it is easy to deform the substrate. Can follow. Further, by using a blocked isocyanate compound used as a curing agent, bleeding (bleeding) of the low molecular component of the base material to the surface layer can be suppressed.

  The content of the fluororesin contained in the toner release layer is not particularly limited, but is preferably in the range of 30 to 70 parts by weight and in the range of 40 to 60 parts by weight with respect to 100 parts by weight of the binder resin. More preferably. The toner release layer may also contain other resin components other than the fluororesin. When the content of the fluororesin contained in the toner release layer is less than 30 parts by mass, the surface energy on the surface of the semiconductive belt member becomes large, so that dirt such as toner adhesion is likely to adhere. There is a case. On the other hand, if the amount is more than 70 parts by mass, it may not be possible to incorporate the necessary amount of other necessary components other than the fluororesin into the toner release layer.

  Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyvinylidene fluoride (PVDF), Tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polyvinyl fluoride (PVF), fluoroolefin-vinyl ether copolymer, fluorine And resins such as vinylidene fluoride-tetrafluoroethylene copolymer and vinylidene fluoride-hexafluoropropylene copolymer. You may use these individually or in combination of 2 or more types.

(Surface roughness)
The ten-point average surface roughness Rz of the surface layer in the semiconductive belt member of the present invention is preferably in the range of 1.5 to 9.0 μm, and more preferably in the range of 3.0 to 6.0 μm. preferable. If the ten-point average surface roughness Rz is less than 1.5 μm, there is a concern that the ten-point average surface roughness Rz is in close contact with the contact member. And the like, and the slight unevenness of discharge due to the unevenness may cause uniform transferability and image quality to deteriorate over time. The ten-point average surface roughness Rz is the surface roughness defined in JIS B0601 (2001).

  The ten-point average surface roughness Rz can be measured using a surface roughness measuring instrument or the like. In the present invention, however, a contact-type surface roughness measuring device (in a 23 ° C./55 RH% environment) Surfcom 570A, manufactured by Tokyo Seimitsu Co., Ltd.) was used. When measuring the surface of the semiconductive belt member, the measurement distance was set to 0.8 mm, and the tip of the contact needle was diamond (5 μmR, 90 ° cone). The average value was determined as the ten-point average surface roughness Rz of the semiconductive belt member.

  The thickness of the surface layer is preferably in the range of 5 μm to 100 μm, and more preferably in the range of 15 to 50 μm. When the thickness of the surface layer is less than 5 μm, the effect of preventing the contamination of the surface of the semiconductive belt member may not be obtained. On the other hand, when the thickness is larger than 100 μm, the surface hardness of the semiconductive belt member becomes unnecessarily large, so that sufficient adhesion to the surface of the image carrier may not be obtained.

<Method for producing semiconductive rubber belt>
The semiconductive rubber belt of the present invention described above can be manufactured by the method for manufacturing a semiconductive rubber belt of the present invention. Below, the manufacturing method of the semiconductive rubber belt of this invention is demonstrated.

First of all, any manufacturing method may be used for manufacturing the belt base material. For example, it is manufactured as follows.
Taking as an example a material obtained by blending chloroprene rubber (CR) and EPDM, for producing a belt base material, for example, conductive filler is mixed and dispersed in chloroprene rubber and EPDM, and then these chloroprene rubber and EPDM are mixed. May be kneaded with a mixer, and a vulcanizing agent may be added to perform extrusion molding.

  Another example of the method for producing a semiconductive rubber belt will be described. After adding and kneading various additives (excluding vulcanizing agents and vulcanization accelerators) including the above-described ion conductive and / or electronic conductive conductive agents to the belt base material, the vulcanizing agent and Add a vulcanization accelerator and knead it with a two-roll to finish it into a sheet. Next, this sheet-like material is preformed into a ribbon shape.

  Subsequently, it shape | molds in a belt shape with the press molding apparatus shown in outline in FIG. Here, the press molding apparatus shown in FIG. 3 will be described. The press molding apparatus has a pair of molds 120 including an upper mold 120A and a lower mold 120B, and a heater 122A capable of heating the inside of the mold 120 on the outside of the upper mold 120A and the lower mold 120B, 122B is provided. Further, the core metal 124A and the core metal 124B are positioned inside the mold 120, and the core metal 124A, the core metal 124B, the upper mold 120A, and the lower mold 120B are closed with the upper mold 120A and the lower mold 120B closed. The space surrounded by is formed into a semiconductive rubber belt. In FIG. 1, (A) shows a state where the mold 120 (upper mold 120A and lower mold 120B) is opened, and (B) shows a state where the mold 120 is closed.

Next, a description will be given of a process of molding the rubber member preformed into the above-described ribbon shape into a belt shape. First, as shown in FIG. 3A, a rubber 126 preformed in a ribbon shape is provided in a space surrounded by the core metal 124A, the core metal 124B, the upper mold 120A, and the lower mold 120B, and the heater 122A and 122B is operated and heated. Subsequently, the upper mold 120A and the lower mold 120B are clamped and pressed with a predetermined clamping force. Then, the ribbon-like rubber 126 spreads in the space and becomes a belt-like shape. Further, the mold is left for a predetermined time, the mold is opened, and the molded semiconductive rubber belt is taken out.
The above is generally known as a press molding vulcanization method, and conditions such as clamping force and time can be appropriately set.

  In this invention, it has the heating process which heat-processes in the state which expanded the semiconductive rubber belt 2 to 10%, after shape | molding a semiconductive rubber belt as mentioned above. Thus, by performing the heat treatment in a state where the molded semiconductive rubber belt is extended, it is possible to suppress a decrease in the tension force over time. Below, a heating process is demonstrated.

  In the heating step, heat treatment is performed in a state where the semiconductive rubber belt is extended. To elongate the semiconductive rubber belt, for example, the semiconductive rubber belt is stretched between a pair of rolls, and either one of them is stretched. By extending the roll as appropriate, the degree of extension can be adjusted, or it can be extended by being stretched around a cylindrical pipe having an appropriate outer diameter.

  The heating temperature in the heating step is preferably 120 to 200 ° C, more preferably 150 to 180 ° C, and still more preferably 160 to 170 ° C. The heating time is appropriately adjusted depending on the heating temperature, but is preferably 10 minutes to 12 hours.

  The heating in the above heating process can be performed by a known heating means such as an oven or a continuous furnace.

  When a surface layer is formed on the surface of the semiconductive rubber belt, it is preferable to perform heat treatment after the surface layer is formed.

<Image forming apparatus>
Next, the image forming apparatus of the present invention will be described. The image forming apparatus of the present invention is an image forming apparatus provided with the above-described semiconductive rubber belt of the present invention. In the image forming apparatus of the present invention, the semiconductive rubber belt is preferably used as an intermediate transfer belt and / or a conveyance belt. The image forming apparatus of the present invention will be described below with reference to the drawings.

  FIG. 4 is a schematic configuration diagram showing an image forming apparatus using the semiconductive rubber belt of the present invention as an intermediate transfer belt. In FIG. 4, the image forming apparatus includes a photosensitive drum 10, an intermediate transfer belt 20 that contacts the photosensitive drum 10 so as to follow the shape of the photosensitive drum 10 in a certain area in order to transfer a toner image from the photosensitive drum 10, and a photosensitive drum. A primary transfer roll 30 for primary transfer of the toner on the body drum 10 onto the intermediate transfer belt 20; In the present embodiment, the photosensitive drum 10 includes a photosensitive layer whose resistance value is reduced by light irradiation. Around the photosensitive drum 10, a charging device 60 for charging the photosensitive drum 10 and a charging device 60 are provided. An exposure device 40 for writing an electrostatic latent image of each color component (each developing device of yellow 51, magenta 52, cyan 53, and black 54) on the charged photosensitive drum 10, and on the photosensitive drum 10. A rotary type developing device 50 that visualizes each formed color component latent image with each color component toner, an intermediate transfer belt 20, and a cleaning brush 71 that cleans residual toner on the photosensitive drum are provided. Yes.

  Here, as the charging device 60, for example, a charging roll is used, but a charger such as a corotron may be used. The exposure device 40 may be any photoconductor that can write an image on a drum with light. In this example, for example, a print head using LEDs is used, but the present invention is not limited to this. Even a print head using a laser may be selected as appropriate, such as a scanner that scans a laser beam with a polygon mirror.

  The rotary developing device 50 is a device in which a developing machine containing each color component toner is rotatably mounted. For example, each color component toner is attached to a portion where the potential is lowered by exposure on the photosensitive drum 10. If there is no particular limitation on the shape and particle size of the toner to be used, it may be selected as long as it is accurately placed on the electrostatic latent image on the photosensitive drum. In this embodiment, the rotary developing device 50 is used, but four developing devices may be used.

  The intermediate transfer belt 20 is stretched over stretching rolls 80A, 80B, 80C and opposing rolls 81A, 81B, 81C, and has a shape along the surface of the photosensitive drum 10 positioned between the rotary developing device 50 and the cleaning brush 71. Thus, only a predetermined contact area is disposed in close contact. Here, the intermediate transfer belt 20 and the photosensitive drum 10 may be driven by separate drive systems. However, in the present embodiment, the intermediate transfer belt 20 is an elastic belt as will be described later, and the photosensitive member. Since they are arranged in contact with the circumferential surface of the drum 10, they are driven to rotate by using the photosensitive drum 10 as a drive source.

  A primary transfer roll 30 as a primary transfer device is disposed in contact with the contact area where the intermediate transfer belt 20 is in close contact with the photosensitive drum 10 from the back side of the intermediate transfer belt 20, and is applied by a predetermined primary transfer bias applying device 30A. The At the secondary transfer position on the downstream side in the running direction of the intermediate transfer belt 20 of the primary transfer device, a counter roll 81A that also serves as a tension roll is disposed on the back side of the intermediate transfer belt 20, and a position facing the roll is as follows. A secondary transfer roll 31 as a secondary transfer device is disposed via the intermediate transfer belt 20, and a predetermined secondary transfer bias is applied to the secondary transfer roll 31 by a primary transfer bias applying device 31A. It has become.

  On the downstream side of the secondary transfer device in the running direction of the intermediate transfer belt, a cleaning and charging device 70 for removing residual toner after secondary transfer and reverse charging is disposed. The cleaning and charging device 70 is formed in a brush shape, and a predetermined bias is applied by the bias applying device 70A. Opposing the cleaning and charging device 70, a counter roll 81 </ b> C that also serves as a stretch roll is disposed on the back side of the intermediate transfer belt 20. The cleaning and charging device 70 is not limited to a brush shape but may be a roll shape.

  In the image forming apparatus according to the present invention, the photosensitive drum 10 rotates in the direction indicated by the arrow in FIG. 4, and the surface of the photosensitive drum 10 is charged by the charging device 60, and then is converted into one color component by the exposure device 40. A corresponding electrostatic latent image is formed, and the electrostatic latent image of one color is visualized (toner image) by the rotary developing device 50 and transferred to the intermediate transfer belt 20 at the site of the primary transfer roll 30. Similarly, the electrostatic latent image of the next color is visualized (toner image), transferred to the intermediate transfer belt 20 at the site of the primary transfer roll 30, and a multicolor toner image is sequentially formed by four color toner images. Is done.

  While such a multi-color toner image is formed, the cleaning and charging member 70 is separated from the surface of the intermediate transfer belt 20, and the multi-color toner image by the four-color toner image is transferred to the secondary transfer roll 31. The image is transferred to the recording material 91 at the site and fixed by the fixing device 90. After the multicolor toner image is transferred to the recording material 91, the cleaning and charging member 70 has a mechanism that moves to the intermediate transfer belt 20 side so as to press-contact the surface of the intermediate transfer belt 20. The nip width between the charging and charging member 70 and the intermediate transfer belt 20 can be increased, and the residual toner is charged in the opposite polarity to the original polarity by the cleaning and charging member 70, and the charged residual toner is transferred to the subsequent photosensitive drum 10. It is transferred to the surface and removed with a cleaning brush.

  In the above image forming apparatus, since the intermediate transfer belt 20 is the semiconductive rubber belt of the present invention, the occurrence of color registration, poor image magnification, belt walk, etc. is suppressed, contributing to excellent image quality and transfer performance. can do.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not restrict | limited to a following example.

[Example 1]
(Rubber kneading A)
The raw material components shown in Table 1 were kneaded with a kneader, and then materials other than the vulcanizing agent and vulcanization accelerator were kneaded with the kneader for 15 minutes.

(Rubber kneading B)
Next, a vulcanizing agent and a vulcanization accelerator were added, and kneading was performed with a two-roll. The kneading finish was a sheet shape having a thickness of 10 mm.
(Preliminary molding)
The sheet taken out by rubber kneading B was preformed into a ribbon shape having a width of 50 mm.
(Press molding vulcanization)
Next, by the press molding vulcanization method schematically shown in FIG. 3, the raw rubber preformed in a ribbon shape in the previous step was set on the top and bottom of the core metal, pressed with a clamping force of 100 kg / cm ² and left for 30 minutes. .

(Polishing)
Next, the vulcanized belt was finished to a thickness of 0.5 mm by grinding the front and back sides with a cylindrical grinder.
(Protective release layer)
After removing the polishing powder of the belt after polishing, spray coating was applied to JLY-601 ESD (manufactured by Japan Atchison Co., Ltd.) to form a protective release layer (surface layer) having a coat thickness of 0.01 mm.
(Baking process)
The semiconductive rubber belt after the formation of the protective release layer was baked in an oven at 150 ° C. for 15 minutes.
After firing, both ends of the belt were cut to adjust the width.
(Heat treatment)
After the formation of the protective release layer, a semiconductive rubber belt was inserted into the cylindrical pipe and was heated in an oven at 150 ° C. for 30 minutes with 5% stretched.
A semiconductive rubber belt was produced as described above.

[Tensioning force measurement]
The tension force maintainability of a semiconductive rubber belt manufactured using the apparatus shown in FIG. 1 was measured. For the measurement, a solid metal shaft made of stainless steel with a diameter of 15 mm was used, a load cell was set inside one shaft, and the tension of the belt was monitored. As for the tension measurement frequency, at least one data was collected per day. The atmosphere was controlled at 25 ° C. ± 2 ° C. and 55% ± 5% RH. The predicted tensile force after 2 years is calculated as follows by calculating a logarithmic approximation formula from the data for 30 days from the belt formation measured as described above, and calculating the value after 2 years (730 days). did. The measurement results are shown in Table 2.

[Image quality evaluation]
In order to evaluate the image quality of an image forming apparatus using the produced semiconductive rubber belt as (1) a transport belt and (2) an intermediate transfer belt, the following evaluation tests were performed.
(1) Conveyor belt The semiconductive rubber belt produced in the image forming apparatus schematically shown in FIG. 5 was attached and actually operated (printed), and walk, longitudinal magnification, and print image quality were evaluated according to the following evaluation criteria.
[Walk evaluation criteria]
○: Belt lateral deviation of 1.5 mm or less Δ: Belt lateral deviation of 3.0 mm or less ×: Belt lateral deviation of more than 3.0 mm [Vertical magnification evaluation criteria]
○: Within the range of 100 ± 5% magnification Δ: Outside the range of 100 ± 5% magnification and within the range of 100 ± 10% magnification ×: Outside the range of 100 ± 10% magnification [Image Quality Evaluation Criteria]
○: No color misregistration or color misregistration less than 200 μm Δ: Color misregistration in the range of 200 to 300 μm ×: Color misregistration over 300 μm

  Here, the image forming apparatus shown in FIG. 5 will be briefly described. The image forming apparatus shown in FIG. 5 is a black and white printer that transfers a toner image formed on the surface of the image carrier 130 to the recording material 132, and the manufactured semiconductive rubber belt is mounted as a transport belt. . In other words, the manufactured transport belt 138, which is a semiconductive rubber belt, is stretched and stretched by a pair of stretch rolls 134 and 136, and the stretch roll 136 has a mechanism that is rotated by a drive motor. It is comprised so that it may drive | work in the arrow direction shown. The recording material 132 is transported by the transport belt 138, and the transfer member 140 is positioned at a position opposite to the portion where the image carrier 130 and the transport belt 138 come into contact, and the recording material transported by the transport belt 138 by the transfer member 140. A toner image is transferred onto the surface of the material 132.

(2) Intermediate transfer belt The prepared semiconductive rubber belt was mounted on DocuPrint C525A manufactured by Fuji Xerox Printing System Co., Ltd., and image quality after continuous printing at 10 kPV was evaluated. This image forming apparatus is equivalent to the printer shown in FIG.
As a result, the belt manufactured in Example 1 showed stable running performance, and good image quality was obtained without color registration.

[Example 2]
A semiconductive rubber belt was produced using the same material and molding method as in Example 1 except that a 2% elongated cylindrical pipe was used during the heat treatment. As a result of the evaluation, the produced belt showed stable running performance, and good image quality was obtained without color registration.

[Example 3]
A semiconductive rubber belt was produced using the same material and molding method as in Example 1 except that a 10% elongated cylindrical pipe was used during the heat treatment. As a result of the evaluation, the produced belt showed stable running performance, and good image quality was obtained without color registration.

[Example 4]
A semiconductive belt was formed using the same material and molding method as in Example 1 except that an 11% elongated cylindrical pipe was used during the heat treatment. As a result of the evaluation, the inner peripheral length of the belt showed an elongation of 1.3%, and the tension damping rate was 33%. As a result of image quality evaluation with the belt attached to the apparatus, a partial vertical magnification failure was observed. This is because the film thickness in the circumferential direction (thin part and thick part) generated in the molding or grinding process is stretched, and the part in the belt circumferential direction is the result of heating with the thin part being stretched most This is thought to be due to the uneven strength.

[Comparative Example 1]
Using the same material and molding method as in Example 1 and evaluating the tension maintenance without annealing, the belt inner circumference showed an elongation of 2.1%, and the tension damping rate was 51.4%. there were. As a result of image quality evaluation with the belt attached to the apparatus, short-circuit density unevenness called smear and a tendency to reduce the vertical magnification were observed.

[Comparative Example 2]
Using the same material and molding method as in Example 1, a conductive fiber sheet was wound around the core and press molded. The belt was set in the same printer as in Example 1, but the belt was not stretched, the belt meandering and slipping occurred, and the function as a transfer belt was not achieved. Such a belt cannot be self-walked and requires a separate movable roll.

[Comparative Example 3]
The same material and molding method as in Example 1 were used, and the core was press-molded by winding a conductive Pvdf sheet around the core. As in Comparative Example 2, the belt did not stretch, and the belt rotated in a meandering manner.

[Comparative Example 4]
A semiconductive belt was formed using the same material and molding method as in Example 1 except that a 1% elongated cylindrical pipe was used during the heat treatment. As a result of the evaluation, the inner peripheral length of the belt showed an elongation of 2%, and the tension damping rate was 50%. As a result of image quality evaluation with the belt attached to the apparatus, short-circuit density unevenness called smear and a tendency to reduce the vertical magnification were observed.

It is a conceptual diagram which shows the measuring apparatus used for the measurement of the tension force of the semiconductive rubber belt of this invention. It is a figure which shows the time-dependent change of the stress at the time of making the elongation rate of the semiconductive rubber belt of this invention different. It is a figure which shows the press vulcanization molding apparatus for shape | molding the semiconductive rubber belt of this invention. 1 is a conceptual diagram illustrating an image forming apparatus to which the present invention is applied. 1 is a conceptual diagram illustrating an image forming apparatus to which the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Photosensitive drum 20 Intermediate transfer belt 30 Primary transfer roll 40 Exposure apparatus 50 Developing apparatus 31 Secondary transfer apparatus 40 Exposure apparatus 50 Developing apparatus 51 Developer Y
52 Developer M
53 Developer C
54 Developer K
60 Charging roll 61 Power supply 70 Cleaning brush 71 Cleaning device 80A 80B 80C Stretch roll 81A 81B 81C Opposing roll 90 Fixing device 91 Recording material

Claims (7)

When stretched by 5% with a biaxial stretch roll under the conditions of 25 ° C ± 2 ° C and 55% ± 5% RH, the tension force damping rate expressed by the following formula (1) is less than 50%. Characteristic semiconductive rubber belt.
Tensile force damping rate (%) = {(initial tension force−predicted tension value after two years) / initial tension force} × 100 (1)
(Here, the predicted tension force after two years is a value calculated from a logarithmic approximation obtained from the result of measuring the tension force for 30 days under the above conditions.) The semiconductive rubber belt according to claim 1, further comprising an ion conductive and / or electronic conductive agent . The semiconductive rubber belt according to claim 1 or 2, wherein the surface has one or more layers. An image forming apparatus comprising: a semiconductive rubber belt according to any one of claims 1 to 3. The image forming apparatus according to claim 4, wherein the semiconductive rubber belt is provided as an intermediate transfer belt and / or a sheet conveying belt .   A method for producing a semiconductive rubber belt, comprising: a heating step of performing a heat treatment in a state where the semiconductive rubber belt is stretched by 2% or more after the semiconductive rubber belt is formed. The method for producing a semiconductive rubber belt according to claim 6, wherein the heating step is performed after forming one or more layers on the surface of the semiconductive rubber belt.

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