JP2005266559A - Conveyer belt and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conveyer belt by which a stable image is obtained by effectively restraining resistance variation caused by time change and environmental change, and an image forming apparatus using the same. <P>SOLUTION: The conveyer belt 1 on the surface of which a toner image or recording material 5 is carried is equipped with belt base material 2 composed of elastic material, a surface adjusting layer 3a which is formed to cover the surface of the base material 2 so as not to spoil the elasticity of the base material 2 and whose resistance can be adjusted, and a back surface adjusting layer 3b which is formed to cover the back surface of the base material 2 so as not to spoil the elasticity of the base material 2 and whose resistance can be adjusted considering the resistance of the adjusting layer 3a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a conveyance belt used in an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an improvement in a conveyance belt having a belt base material made of an elastic material and an image forming apparatus using the same.

In an image forming apparatus such as a copying machine, a printer, or a facsimile, an image is formed on an image carrier such as a photosensitive drum, and the image is indirectly transferred to a recording material via an intermediate transfer belt, There is already provided one that directly transfers to a recording material on a recording material conveyance belt.
By the way, in this type of image forming apparatus, taking an intermediate transfer type as an example, an intermediate transfer belt as a conveyance belt is often used in a form using a hard resin material as a belt base material. Problems such as image omission due to a concentrated load on (for example, a toner image) are observed.
In order to solve such a problem, for example, as shown in Patent Document 1, an elastic material such as a flexible rubber material is used as a belt base material, thereby reducing the concentrated load on the toner image, It is preferable to fundamentally solve problems such as omission.

This type of intermediate transfer belt has the advantage of using the elasticity of the belt base material to ensure a sufficient nip area with the image carrier, but it depends on the rubber material used as the belt base material. The characteristic change is also large.
In general, the intermediate transfer belt is driven to rotate across a plurality of stretching members, and the rubber material used is required for the intermediate transfer belt, for example, ozone resistance, flame retardancy, etc. Various chemicals are added for plasticity and anti-aging properties. For this reason, so-called bleed in which various chemicals are deposited on the rubber surface may occur due to changes over time.
When such bleeding or the like occurs, the characteristics required for the intermediate transfer belt change, and stickiness of the intermediate transfer belt, surface cracks, and the like occur.
Therefore, in order to suppress the characteristic change, the rubber material of the belt base material is a mixed base material of chloroprene rubber (CR) and EPDM, and two different conductive carbon blacks (acetylene black and furnace black or acetylene are contained in the base material). A proposal has been made to disperse black and ketjen black) (see, for example, Patent Document 2). According to this type, ozone resistance can be improved by using a mixed base material of CR and EPDM for the belt base material, and furthermore, by dispersing two different conductive carbon blacks, The characteristic can be stabilized. However, even if the technique described in Patent Document 2, for example, is adopted, the back surface of the belt base material that has not been treated is not directly affected by ozone deterioration due to bias application or the like.

  Patent Document 3 proposes a transfer belt having a configuration in which elastic layers are provided on both sides of a fiber layer and a resin layer is coated on any elastic layer. According to this type, the reinforcing effect of the belt strength by the fiber layer is improved, but the coating of the resin layer on both sides is not presented, and the effect of preventing bleeding or the like cannot be expected. Further, when there is a fiber layer, the hardness of the belt itself cannot be made soft, and problems such as image omission occur at the same time.

JP 2002-268398 A (Means for Solving the Problems) JP-A-9-179414 (Embodiment of the Invention, FIG. 1) Japanese Patent Laid-Open No. 11-249450 (Means for Solving the Problem and Embodiment of the Invention)

In any of the configurations of Patent Documents 1 to 3 described above, the coating on only one side of the belt base material is presented, and no coating is applied to the back surface side.
In general, in an intermediate transfer belt using a rubber material, it is well known that various coatings are formed on the surface carrying a toner, that is, the surface of the intermediate transfer belt. For example, a resistance adjusting layer for stabilizing the transfer electric field, a release layer for preventing toner from sticking, and the like can be mentioned. On the other hand, the back surface is usually subjected to mechanical finishing by polishing, and the polished surface is exposed as it is.
Further, when such an intermediate transfer belt is used, when removing the residual toner on the belt, mechanical performance such as a blade as a cleaning member tends to be insufficient in removal performance, and a brush-like member is used and bias application is performed. A method of removing by going is used. This cleaning bias is applied with a high electric field (for example, several times the electric field when a toner image is transferred from an image carrier such as a photosensitive member to an intermediate transfer belt), and therefore, particularly in the pre-nip region with the cleaning member. Medium discharge occurs and ozone is generated. The generated ozone causes the rubber to be oxidized or deteriorated, and due to environmental deterioration, the belt base material is cracked, or the discharge products such as NOx (nitrogen oxide) are attached.

In such a case, various coatings are formed on the surface of the intermediate transfer belt, and the surface is subjected to removal of deposits including residual toner by a cleaning member or the like. Is less likely to stay. Furthermore, the bleed is suppressed by this coating.
On the other hand, since the back surface of the polished surface is not particularly a facing member that rubs on the back surface, it is simply pressed against the tension member of the intermediate transfer belt, so that the effect of removing the deposit on the back surface is expected. Can not. Therefore, on the back surface, the above-described cracks and deposits (discharge products) cause mechanical strength reduction and impair moisture resistance. In particular, the deposited NOx is combined with moisture. As a result, the impedance of the back surface is lowered, and as a result, the resistance of the intermediate transfer belt is changed, and it is difficult to apply an appropriate transfer electric field.

Such a technical problem is not limited to the case where the conveyance belt is an intermediate transfer belt, but may also occur in the case of a recording material conveyance belt.
The present invention has been made to solve the above technical problem, and uses a conveyor belt that effectively suppresses resistance fluctuations due to changes over time and environmental changes and that can obtain a stable image, and the same. An image forming apparatus is provided.

  That is, according to the present invention, as shown in FIG. 1A, a conveyor belt 1 carrying a toner image or a recording material on its surface, a belt base material 2 made of an elastic material, and the elasticity of the belt base material 2 The surface adjustment layer 3a is coated on the surface of the belt base 2 so as not to impair the belt, and the resistance can be adjusted. The surface adjustment layer 3a is coated on the back of the belt base 2 so as not to impair the elasticity of the belt base 2. And a back surface adjustment layer 3b capable of adjusting the resistance in consideration of the resistance of the layer 3a.

In such technical means, the conveying belt 1 may be appropriately selected as long as it has a belt base 2 made of an elastic material. For example, an image forming apparatus is used as an intermediate transfer belt or a recording belt. There is a material transport belt.
The belt base material 2 is not particularly limited as long as it uses an elastic material, and examples thereof include a synthetic rubber material or an elastomer material. Further, for example, a conductive filler for resistance adjustment is included in the belt base material 2. Various additives including the reinforcing fibers (including reinforcing fibers) can be included.
Furthermore, “does not impair the elasticity of the belt base material 2” only needs to provide elasticity as a conveying belt by providing an adjustment layer.
Furthermore, from the viewpoint of further preventing image omission and blurring, the Young's modulus of the belt substrate 2 is 8 MPa or less, preferably 3 to 5 MPa.
In the present invention, “resistance can be adjusted” means that, for example, a conductive agent or the like is put in the adjustment layer and the volume resistivity can be adjusted as necessary. Therefore, for example, a mode in which the resistance is adjusted only for the front surface adjustment layer 3a and the resistance is not adjusted for the back surface adjustment layer 3b (including the resistance of the material itself) is also included.

The front surface adjustment layer 3a and the back surface adjustment layer 3b in the present invention may have a laminated structure. For example, the aspect provided with a mold release layer in the surface adjustment layer 3a may be sufficient.
Moreover, the surface adjustment layer 3a and the back surface adjustment layer 3b are constituted by a resin layer using at least one of a polyurethane resin, a polyester resin, and an acrylic resin as a binder in that a stable coating layer 3 can be constructed over a long period of time. It is preferable that the coating layer 3 further includes various additives such as a conductive agent and a flame retardant. In addition, the binder used for the surface adjustment layer 3a and the back surface adjustment layer 3b may be the same or different.

In the present invention, the volume resistivity of the surface adjustment layer 3a or the back surface adjustment layer 3b including the belt substrate 2 is equal to or higher than the volume resistivity of only the belt substrate 2 not including the adjustment layer. It is preferable that the resistance of the front surface adjustment layer 3a and the back surface adjustment layer 3b is higher than that of the belt base material 2, and the influence of resistance unevenness in the belt base material 2 can be reduced. Is suppressed from being concentrated at a specific location, and the transfer current is uniformly distributed, thereby enabling stable transfer conditions.
Further, the surface adjustment layer 3a preferably contains a conductive agent in the surface adjustment layer 3a from the viewpoint of stabilizing the transfer conditions in a low temperature and low humidity state and making it resistant to environmental fluctuations. Can avoid the nature. In addition, as an outer layer of the surface adjustment layer 3a, a release layer made of, for example, a fluorine resin can be provided.
And judging from the mechanical action of the conveyance belt 1 in the present invention, the aspect of the conveyance belt 1 is set by setting the total film thickness of the front surface adjustment layer 3a and the back surface adjustment layer 3b not to exceed 30 μm. However, even if the conveyor belt 1 is held for a long time while being stretched, it is possible to prevent deformation such as curling.

Furthermore, in the aspect in which the back surface adjustment layer 3b does not contain a conductive agent, the film thickness that functions as a resistance adjustment layer is maintained, and the electrical operation that is stable as the resistance adjustment layer even in a low temperature and low humidity state. In consideration of the upper limit film thickness for achieving the above, the thickness of the back surface adjustment layer 3b is preferably 1 μm or more and 7 μm or less.
In particular, in the present invention, by providing the back surface adjustment layer 3b, it is possible to prevent the surface of the belt base material 2 from coming into direct contact with other members and to prevent direct contact with outside air. There is an effect of suppressing deterioration over time such as bleeding of the additive from the material 2 and environmental deterioration due to ozone, NOx and the like.

The present invention is intended for the conveyor belt 1, but is not limited thereto, and is also intended for an image forming apparatus using the same.
In this case, as shown in FIG. 1B, for example, the present invention includes an image carrier 4 and a conveyance belt 1 facing the image carrier 4, and an image formed on the image carrier 4 is transferred to the conveyance belt 1 or this belt. The image forming apparatus for transferring to the recording material 5 on the conveyance belt 1 is characterized in that the conveyance belt 1 is provided with the above-described conveyance belt.

Here, in a mode in which the transport belt 1 is used as an intermediate transfer belt, as shown in FIG. 1B, the toner image on the image carrier 4 is transferred by the primary transfer device 6 to the transport belt (intermediate transfer belt). ) After primary transfer to 1, the toner image on the conveying belt (intermediate transfer belt) 1 is secondarily transferred to the recording material 5 by the secondary transfer device 7.
On the other hand, in the embodiment in which the conveyance belt 1 is used as a recording material holding belt, as shown in FIG. 1B, after holding the recording material 5 on the conveyance belt (recording material holding belt) 1, the image is carried. The toner image on the body 4 is transferred to the recording material 5 on the conveying belt (recording material holding belt) 1 by the transfer device 8.

Further, in the image forming apparatus shown in FIG. 1B, it is preferable that the conveying belt 1 is stretched around a plurality of stretching members 9 and arranged in contact with the drum-shaped image carrier 4.
According to this aspect, by causing the conveying belt 1 to follow the shape of the image carrier 4 as much as possible, discharge due to useless gaps before and after the nip area during transfer can be eliminated, and scattering of the toner image can be prevented. it can.
Furthermore, it is preferable that either one of the image carrier 4 and the conveyance belt 1 be a drive source and the other be driven to rotate.
According to this aspect, by adopting such a drive configuration, one drive mechanism can be omitted, and accordingly, the drive cost can be suppressed, and from the drive interference between the transport belt 1 and the image carrier 4. Fluctuation factors such as fluctuations in the thickness of the coming conveyor belt 1 and feed fluctuations in the process direction can be excluded.

According to the present invention, the surface of the belt base material made of an elastic material can be adjusted so that the elasticity of the belt base material is not impaired and the resistance can be adjusted. Since the back surface adjustment layer capable of adjusting the resistance is provided so as not to impair the elasticity of the belt, it is possible to provide a conveyor belt that makes use of the elasticity as it is.
Further, the belt base material is not in direct contact with the outside air, and there is an effect of suppressing deterioration with time such as bleeding from the belt base material and environmental deterioration due to ozone, NOx, and the like. Furthermore, a stable electric action can be maintained even under low temperature and low humidity, and a conveyor belt that is resistant to environmental fluctuations can be obtained.
In addition, in an image forming apparatus using such a conveyor belt, it is possible to suppress image deterioration such as image omission and blur by suppressing deterioration with time and environmental degradation of the conveyor belt. A forming apparatus can be easily constructed.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 2 shows an embodiment of an image forming apparatus to which the present invention is applied.
In FIG. 1, the image forming apparatus contacts the photoconductive drum 10 along the shape of the photoconductive drum 10 in a certain area in order to transfer a toner image from the photoconductive drum 10. 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 11 for charging the photosensitive drum 10 and An exposure device 12 for writing an electrostatic latent image of each color component (in this example, yellow (Y), magenta (M), cyan (C), black (K)) on the charged photosensitive drum 10, and a photosensitive member. A rotary developing device 13 that visualizes each color component latent image formed on the drum 10 with each color component toner, the intermediate transfer belt 20, and a cleaning device 17 that cleans residual toner on the photosensitive drum 10. Are arranged.

Here, as the charging device 11, for example, a charging roll is used, but a charging device such as a corotron may be used.
The exposure device 12 may be any device that can write an image on the photosensitive drum 10 with light. In this example, for example, a print head using LEDs is used, but the present invention is not limited to this, and EL is used. For example, a scanner that scans a laser beam with a polygon mirror may be selected as appropriate.
Further, the rotary type developing device 13 is rotatably mounted with developing units 13a to 13d containing respective color component toners. For example, the respective color component toners are attached to a portion of the photosensitive drum 10 where the potential is lowered by exposure. The toner to be used is not particularly limited in shape and particle size, and any toner may be used as long as it is accurately placed on the electrostatic latent image on the photosensitive drum 10. In this example, the rotary developing device 13 is used, but four developing devices may be used.
Furthermore, the cleaning device 17 may be appropriately selected as long as it cleans the residual toner on the photosensitive drum 10 and employs a blade cleaning method. However, there may be a mode in which the cleaning device 17 is not used when toner having a high transfer rate is used.

Further, the intermediate transfer belt 20 is laid around four stretching rolls 21 to 24, and is predetermined along the surface of the photosensitive drum 10 positioned between the rotary developing device 13 and the cleaning device 17. Only the contact region is closely arranged.
Here, the intermediate transfer belt 20 and the photosensitive drum 10 may be driven by separate drive systems, but in the present embodiment, the intermediate transfer belt 20 is an elastic belt as described later, The intermediate transfer belt 20 is driven and rotated by using, for example, the photosensitive drum 10 as a driving source because it is disposed in contact with the circumferential surface of the photosensitive drum 10.

A primary transfer roll 25 as a primary transfer device is disposed in contact with a part of 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 a predetermined primary transfer bias is applied. Applied.
Furthermore, a secondary transfer roll 30 as a secondary transfer device is disposed opposite to the tension roll 22 of the intermediate transfer belt 20 with the tension roll 22 as a backup roll, for example, the secondary transfer roll 30. A predetermined secondary transfer bias is applied to the tension roller 22 and the tension roll 22 that also serves as a backup roll is grounded.
Furthermore, a cleaning brush 26 as a belt cleaning device is disposed at a portion of the intermediate transfer belt 20 facing the stretching roll 23, and a predetermined cleaning bias is applied to the cleaning brush 26 so that the stretching brush 23 is stretched. The roll 23 is grounded.
A recording material 40 such as paper is accommodated in a supply tray 41, supplied by a pickup roll 42, guided to a secondary transfer portion through a registration roll 43, and then to a fixing device 45 through a conveyance belt 44. It is conveyed and discharged to a discharge tray 48 through a transfer roll 46 and a discharge roll 47.

Further, in the present embodiment, as shown in FIG. 3, the intermediate transfer belt 20 covers a belt base material 51 made of an elastic material, a surface coating layer 52 that covers the surface of the belt base material 51, and the back surface. It is comprised by the back surface coating layer 53. FIG.
Here, examples of the belt substrate 51 used in the present embodiment include vulcanized rubber and thermoplastic elastomer. Here, examples of the raw rubber material include general diene rubbers such as styrene / butadiene rubber (SBR), isoprene rubber (IR), EPDM, butadiene rubber (BR), acrylic rubber (ACM, ANM) and the like. However, nitrile rubber (NBR), hydrogenated NBR, and chloroprene rubber are relatively high in rigidity, have a volume resistivity close to semiconductivity per se, and have good fluidity in a mold. (CR), epichlorohydrin rubber (CO, ECO), urethane rubber (U), silicone rubber (Si) 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.
Furthermore, the material of the belt substrate 51 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.

In addition, a conductive filler or an insulating filler can be added to the belt substrate 51 to adjust the volume resistivity of the belt substrate 51.
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, metal salts such as zinc oxide, potassium titanate, tin oxide, graphite, LiClO ₄ , LiAsF ₆ , various quaternary ammonium salts, and the like. Examples thereof include silica.
In addition to the above components, the following materials for rubber can be used for the belt base 51. For example, as filler, titanium oxide, magnesium oxide, calcium carbonate, calcium sulfate, etc., clay, talc, silica, etc., and as rubber chemicals, vulcanizing agent, vulcanization accelerator, anti-aging agent, plasticizer, process oil And coloring agents.

The belt base material 51 can be manufactured using any manufacturing method, but is manufactured as follows, for example.
For example, a material in which chloroprene rubber (CR) and EPDM are blended is taken as an example. To manufacture the belt substrate 51, for example, conductive filler is mixed and dispersed in chloroprene rubber and EPDM, and then these chloroprene rubbers are mixed. And EPDM may be kneaded with a mixer, and a vulcanizing agent may be added to perform extrusion molding.
Here, when the kneaded belt base material 51 is extrusion-molded, the kneaded belt base material 51 is covered with a cylinder having the same outer diameter as the metal belt inner diameter called a vulcanization mandrel. Vulcanization is performed under predetermined conditions (for example, approximately 150 hours at 150 ° C.), and then secondary vulcanization is performed under predetermined conditions (for example, approximately 15 hours at 110 ° C.) while changing the time according to the required modulus. Do. Thereafter, the belt base material 51 is covered with a polishing mandrel, and the inner peripheral surface and outer peripheral surface of the belt base material 51 are polished to obtain surface smoothness.
In the present embodiment, the belt base material 51 is obtained by kneading EPDM into CR, dispersing paraffin oil during kneading to facilitate kneading, and adding a vulcanization accelerator during curing. The volume resistance value is 7 to 12 LogΩ by adding a conductive filler.

Further, the surface coating layer 52 is made of a polyurethane resin, a polyester resin, or an acrylic resin as a binder, and a predetermined filler, typically a lubricant filler, a conductive filler, and an insulating filler are dispersed therein.
Here, as the lubricating filler, resin powders of fluorine compounds such as PTFE, ETFE, and PFA are used, and the surfactant is used in a dispersed form as necessary.
On the other hand, examples of the conductive filler include powders such as carbon black, white carbon, titanium oxide, tin oxide, magnesium oxide, silicon antimony oxide, and aluminum oxide.
Examples of the insulating filler include various pigments and silica.
In this embodiment, a predetermined amount of conductive filler and 5 wt% insulating filler are added to the polyurethane resin, and a thickness of 7 to 15 μm and a surface resistance value of 9 to 14 LogΩ / □ are used. .

  Further, in the present embodiment, a release layer 52 a having toner releasability is applied to the outer layer of the surface coating layer 52. This release layer 52a is obtained by dispersing a powder of a lubricating filler (PTFE, ETFE, PFA) in an aqueous polyurethane emulsion using a surfactant. In this embodiment, 5 wt% PTFE is used. What was dispersed was used. And when this mold release layer 52a is hardened, PTFE is unevenly distributed on the surface, and the mold release layer 52a provided with the desired mold release property is formed.

And the back surface coating layer 53 in this Embodiment is comprised by what does not contain the conductive filler of the surface coating layer 52, and becomes a layer with a film thickness of 1-7 micrometers and a volume resistivity of 10 < ⁹ > -10 < ¹⁴ > ohm * cm. ing.
Here, the lower limit of the film thickness of the back surface coating layer 53 is set to 1 μm, and if it is thinner than this, it is difficult to form a film that protects the belt substrate 51 (it is difficult to form a continuously covered film). And an electrical effect (operational effect as a resistance adjustment layer that reduces the influence of resistance unevenness of the belt base material 51) is necessary. On the other hand, the upper limit of the film thickness is set to 7 μm. If the film thickness is made thicker than this, the intermediate transfer belt 20 is stretched around the stretching rolls 21 to 24, and curling remains, and the ion conductive behavior particularly at low temperature and low humidity. This is because there is a concern that the environmental fluctuation of the resistance becomes large when the thickness exceeds a certain level.
The surface coating layer 52 and the back surface coating layer 53 may be applied on the belt substrate 51 by dip coating, spray coating, electrostatic coating, roll coating, or the like.

Further, in the present embodiment, when the surface roughness of the back surface coating layer 53 is smooth, the opposing members such as the stretch rolls 21 to 24 and the intermediate transfer belt 20 are in close contact with each other, which may cause bleeding. Therefore, the surface roughness Rz of the back surface coating layer 53 is preferably 1.5 μm or more.
Regarding the adjustment of the surface roughness, the surface of the back surface coating layer 53 may be polished in a polishing process (the polishing mandrel is covered with the intermediate transfer belt 20 to polish the surface of the belt) as necessary. In addition, when it is necessary to adjust the surface roughness of the surface coating layer 52, it becomes possible by carrying out similarly.

Next, the operation of such an image forming apparatus will be described with reference to FIGS. 3 and 4A and 4B.
In FIG. 3, when the image forming apparatus starts an image forming operation, each color component toner image on the photosensitive drum 10 is sequentially formed and is primarily transferred onto the intermediate transfer belt 20 sequentially by the transfer electric field of the primary transfer roll 25.
Thereafter, the toner image primarily transferred to the intermediate transfer belt 20 is secondarily transferred to the recording material 40 by the transfer electric field of the secondary transfer roll 30, and is carried to the fixing step.

In such an image forming process, the intermediate transfer drum 20 in the present embodiment has a Young's modulus of 3 to 5 MPa, so that the pressure applied to the intermediate transfer belt 20 at the time of transfer is uniformly dispersed, and image omission and blurring occur. Can be further reduced.
In particular, by providing the back surface coating layer 53 on the back surface of the intermediate transfer belt 20, the belt base material 51 does not come into direct contact with the outside air, and the influence of ozone generated in the image forming apparatus can be reduced. Furthermore, bleeding from the intermediate transfer belt 20 can be prevented.

Further, FIGS. 4A and 4B schematically show the influence of NOx on the back surface coating layer 53 applied to the back surface of the intermediate transfer belt 20 in the present embodiment. FIG. In the embodiment, an example in which the back surface coating layer 53 is formed and (b) shows an example in which the belt base material surface is exposed as it is on the back surface of the intermediate transfer belt 20.
If no protective layer is provided on the back surface of the intermediate transfer belt 20 as shown in FIG. 4B, the belt base is caused by the transfer electric field between the photosensitive drum 10 and the primary transfer roll 25 during transfer. Due to resistance unevenness in the material 51, the transfer electric field is likely to be concentrated locally, and it is difficult to apply a uniform electric field. Further, when printing is repeated, ozone and NOx are generated by discharge, and this NOx tends to accumulate on the unevenness of the surface of the belt base material 51 (the unevenness on the surface that is just polished). The accumulated NOx reacts with moisture in the air, and a highly conductive layer is formed on the back surface of the belt substrate 51. Therefore, the belt surface resistance accompanying the deterioration of the back surface is reduced, and the transfer current flows laterally, so that the original image cannot be transferred.

On the other hand, in this embodiment, since the back surface coating layer 53 is formed on the back surface of the intermediate transfer belt 20 as shown in FIG. The belt 20 becomes possible.
Furthermore, by setting the film thickness of the back surface coating layer 53 to 1 to 7 μm, the resistance increase due to the back surface coating layer 53 is not a problem even in a low temperature and low humidity environment, and the stabilization of the transfer conditions is maintained.

  Furthermore, in this embodiment, since the intermediate transfer belt 20 is driven and rotated by driving the photosensitive drum 10, the drive control cost of the intermediate transfer belt 20 can be greatly reduced. In particular, in the present embodiment, since a wide transfer nip area between the photosensitive drum 10 and the intermediate transfer belt 20 is ensured, it is possible to reduce the pressure in the transfer nip area. The situation where the body drum 10 and the intermediate transfer belt 20 are completely in close contact with each other is more reliably avoided.

  In the present embodiment, the photosensitive drum 10 and the intermediate transfer belt 20 are placed in contact with each other in an overlapping state, and the intermediate transfer belt 20 is driven based on the driving force from the photosensitive drum 10. However, the present invention is not limited to this. The photosensitive drum 10 and the intermediate transfer belt 20 have separate drive systems, and the intermediate transfer belt 20 is linearly connected to the photosensitive drum 10. Of course, the present invention can also be applied to an embodiment in which contact is made.

In this example, the relationship between the total film thickness of the front surface coating layer and the back surface coating layer of the intermediate transfer belt and the deformation of the intermediate transfer belt was examined with the same configuration as that of the above-described embodiment.
The total film thickness is within the range of 1 to 7 μm of the back coating layer, a sample is prepared so that the total film thickness is 10 to 35 μm, and the intermediate transfer belt is stretched in a high-temperature and high-humidity environment. Thereafter, the intermediate transfer belt was loosened and the deformation was visually confirmed.
As a result, as shown in FIG. 5, deformation was not confirmed up to 10 to 30 μm, but at 35 μm, traces of the stretching roll remained and large deformation was observed.
Further, when the total film thickness was examined in detail, it was confirmed that when the total film thickness was 30 μm or less, the deformation of the intermediate transfer belt did not become a practically problematic level.

(A) is explanatory drawing which shows the outline | summary of the conveyance belt which concerns on this invention, (b) is explanatory drawing which shows the outline | summary of the image forming apparatus concerning this invention. 1 is an explanatory diagram showing an embodiment of an image forming apparatus according to the present invention. FIG. 3 is a cross-sectional view of an intermediate transfer belt used in the embodiment. (A) is explanatory drawing which shows the effect | action of the intermediate transfer belt which concerns on this invention, (b) is explanatory drawing which shows the effect | action of the conventional intermediate transfer belt as a comparison. It is explanatory drawing which shows the result of an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Conveyance belt, 2 ... Belt base material, 3 ... Coating layer, 3a ... Surface coating layer, 3b ... Back surface coating layer, 4 ... Image carrier, 5 ... Recording material, 6 ... Primary transfer apparatus, 7 ... Secondary transfer Device 8 ... Transfer device 9 ... Stretch member

Claims (8)

A conveyor belt carrying a toner image or recording material on its surface,
A belt base material made of an elastic material;
A surface adjustment layer that is coated on the surface of the belt base material and can adjust resistance so as not to impair the elasticity of the belt base material;
A transport belt comprising: a back surface adjustment layer that is coated on the back surface of the belt base material so as not to impair the elasticity of the belt base material and that allows resistance adjustment in consideration of the resistance of the surface adjustment layer. In the conveyance belt of Claim 1,
The transport belt, wherein the front surface adjustment layer and the back surface adjustment layer are formed of a resin layer using at least one of polyurethane resin, polyester resin, and acrylic resin as a binder. In the conveyance belt of Claim 1,
A transport belt, wherein the volume resistivity of the front surface adjustment layer or the back surface adjustment layer including the belt base material is adjusted to be equal to or higher than the volume resistivity of only the belt base material not including the adjustment layer. In the conveyance belt of Claim 1,
The belt is composed of an elastic material having a Young's modulus of 8 MPa or less. In the conveyance belt of Claim 3,
The surface adjustment layer contains a conductive agent. In the conveyance belt in any one of Claims 1 thru | or 5,
A conveyance belt, wherein the total film thickness of the surface adjustment layer and the back surface adjustment layer is set in a range not exceeding 30 μm. In the aspect in which the back surface adjustment layer does not include a conductive agent among the transport belt according to claim 6
The back surface adjusting layer is composed of a layer having a thickness of 1 μm or more and 7 μm or less. In an image forming apparatus that includes an image carrier and a conveyance belt facing the image carrier, and transfers an image formed on the image carrier to a conveyance belt or a recording material on the conveyance belt.
An image forming apparatus comprising the conveyance belt according to claim 1.

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