JPH08185060A - Transfer belt manufacturing method and transfer conveyor belt device - Google Patents

Abstract

PURPOSE: To reduce the contamination of the rear of a transfer belt with the transfer material by forming the surface of the belt with foamed thin layer. CONSTITUTION: The toner formed on an image carrier is electrostatically transferred on a transfer material S, and the surface of a transfer belt 6 conveying the material S is formed with a foamed film layer. The belt 6 has a double-layer structure and consists of an inner-face layer formed with a rubber belt obtained by kneading a chloroprene rubber mixed with carbon, forming the kneaded rubber and grinding the formed body to 0.4mm thickness and the surface layer 6b of a foamed-urethane film. The surface layer 6b is formed by mixing a foaming material into the urethane to constitute a base material, applying the mixture on a rubber belt to form the inner face and heating the mixture which is cured to form a foamed film layer having cells. The diameter of the cell is adjusted by the amt. of the foaming agent. The upper face of surface layer 6b is made rugged by the innumerable cells exposed on the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer / conveying belt device and a method for manufacturing a transfer belt used in the device.

[0002]

2. Description of the Related Art A toner image formed on an image carrier is electrostatically transferred onto a transfer material, and the surface of a transfer belt that conveys the transfer material has residual toner remaining on the surface of the image carrier. Toner, paper dust, or the like floating in the device adheres electrostatically or by pressure contact. As a method for cleaning such dirt (mainly toner) attached to the transfer belt, a smooth coating layer is formed on the belt surface by using a material having a low friction coefficient or a material having a good releasability from the toner, and a cleaning plate is formed. Thus, dirt such as toner attached to the coating layer is scraped off for cleaning.

[0003]

A problem in molding a transfer belt is how to coat a stretchable elastic belt with a material having a low coefficient of friction, that is, a hard material. A material having a low coefficient of friction has a lower coefficient of friction as it is harder and exhibits its original properties. However, when the elastic belt is coated with the material, the tension of the belt becomes high and the material does not stretch. When the belt in this state is forcibly stretched, a crack is formed in the coating layer on the belt surface and toner enters the cracked portion, which makes it difficult to scrape with a cleaning plate, resulting in poor cleaning of the transfer belt surface. . This crack is hardly present in the initial state in which the transfer / transport belt is wound around the unit, but gradually grows when the device is driven and the transfer belt runs. Further, even with a transfer belt coated with the same material, the occurrence of cracks is not uniform due to variations in firing conditions after coating and surface roughness of the elastic body that forms the base of the belt before coating, and the size of the cracks and Managing numbers is virtually impossible. Conversely,
If a material with a low coefficient of friction and a relatively soft material is used so that it can follow an elastic low belt, the tension of the belt will not increase so much and cracks will be suppressed, but the coefficient of friction on the surface of the belt will increase. However, there is a problem in that the releasability of the sheet becomes poor and cleaning failure of the transfer belt is caused. As described above, the low friction and the softness of the coating are in a contradictory relationship, and it is difficult to actually select the coating material even with a cleaning blade, and the surface of the transfer belt is currently contaminated with toner. The toner remaining on the transfer belt adheres to the back surface of the transfer paper,
This causes so-called back stain.

[0004]

In view of the above, according to the present invention, the surface of the transfer belt for electrostatically adsorbing the toner formed on the image carrier to the transfer material and conveying the toner is formed of a foam film layer. There is. In the invention of claim 2, the diameter of the foam cell of the foam film layer is formed larger than the average particle diameter of the toner used. According to the third aspect of the invention, a member to which a bias having a polarity opposite to that of the toner used is applied or a brush-shaped member to which no bias is applied is provided as the toner removing unit. According to the invention of claim 4, after forming the foamed film layer on the surface of the transfer belt, the transfer belt is subjected to a processing step of grinding or polishing the foamed film layer.

[0005]

According to the first aspect of the invention, the toner formed on the image carrier is electrostatically transferred onto the transfer material, and the surface of the transfer belt carrying the transfer material is covered with the foam film layer. Since it is formed, the toner on the image carrier is caught on the foamed portion on the surface of the transfer belt and is captured on the transfer belt. According to the second aspect of the present invention, since the foamed cell diameter of the foamed film layer is formed larger than the average particle diameter of the toner, a large amount of toner is captured by one foamed cell. According to the third aspect of the present invention, since the toner removing means is provided as a member to which a bias having a polarity opposite to the polarity of the toner is applied or a brush-like member to which the bias is not applied, the toner is captured by the foam cells of the transfer belt. The toner is electrostatically captured by the member to which the bias is applied, and is scraped off by the brush-shaped member that is not applied with the bias to clean the transfer belt. According to the invention of claim 4, after the foamed film layer is molded on the surface of the transfer belt, a processing step of grinding or polishing the foamed film layer is performed. Therefore, at the time of molding the foamed film layer, the skin layer is formed on the surface layer of the film layer. Even when the film is formed, the skin layer is removed and the foam cells in the foam film layer are exposed on the belt surface.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A transfer / conveying belt device indicated by reference numeral 1 in FIG.
The belt unit 2 is detachably supported on the main body 1A. The belt unit 2 includes a transfer belt 6 wound around a driving roller 5 and a driven roller 4 for transferring a developed image from a drum-shaped photosensitive body 3 which is an image carrier shown in FIG. D to contact / separate from the photoconductor 3
A C solenoid 8, a contact / separation lever 9, a bias roller 11 that applies a transfer bias to the transfer belt 6, a contact plate 13 that removes electric charges from the transfer belt 6, and a belt cleaning device 1.
6 is provided. The high voltage power supply 12 for applying a voltage to the bias roller 11 is provided in the main body 1A shown in FIG. As shown in FIGS. 1 and 2, the drive roller 5 has a gear 5b connected to a drive motor (not shown) at one end thereof and is driven to rotate.

The transfer belt 6 can be moved in the conveying direction of the transfer paper S (direction of arrow A in FIG. 3) at a position facing the photoconductor 3 in accordance with the rotation of the driving roller 5. As shown in FIG. 5, the transfer belt 6 has a two-layer structure, and the surface layer 6b has a surface resistivity of 1 × 10 ⁹ when the electric resistance measured by JIS K6911 is DC 100 v. Ω ~ 1 x 10
¹² Ω, the surface resistivity of the inner layer 6a is 1 × 10 ⁷ Ω to 1 × 1
To 0 ⁹ Omega, and a volume resistivity of 5 × 10 ⁸ Ω · cm~
It is set within the range of 5 × 10 ¹⁰ Ω · cm.

The driven roller 4 and the driving roller 5 are rotatably supported by a support 7 as shown in FIGS. The support 7 is swingable in the transfer paper transport direction indicated by the arrow A with a support shaft 5a of the drive roller 5 located downstream of the transfer position with respect to the photoconductor 3 as a fulcrum. The support 7 includes a DC solenoid 8 on the transfer position side of the transfer belt 6 driven by a signal from the control plate 8A.
Operated by. That is, the contact / separation lever 9 is connected to the DC solenoid 8, and the contact / separation lever 9 is connected.
Moves the support 7 to bring the transfer belt 6 into contact with and separate from the photoconductor 3.

In the control plate 8A, the front end of the transfer sheet S conveyed in a state of being aligned with the front end position of the toner image formed on the photoconductor 3 by the registration roller 10 which is a paper conveyance means has the photoconductor 3 at the front end. Drive signal is emitted when D approaches
The C solenoid 8 is driven. Therefore,
When the solenoid 8 is driven, the support 7 comes close to the photoconductor 3 and the transfer belt 6 comes into contact with the photoconductor 3, so that the transfer sheet S is moved to the photoconductor 3 at a position facing the photoconductor 3.
Transfer nip part B that can be transported while being in contact with
Is formed.

As shown in FIG. 2, the surface shape of the driven roller 4 is such that both ends 4a, 4a are tapered in the axial direction so as to prevent the transfer belt 6 from being offset. . The driven roller 4 is a conductive roller made of metal or the like, but only supports the transfer belt 6 having the electric resistance as described above, and is not electrically directly connected to another conductive member. The drive roller 5 has a function of increasing the grip force with respect to the transfer belt 6 during driving, and thus, the EPDM
A material such as rubber, chloroprene rubber, or silicone rubber is selected.

The bias roller 11 is provided on the downstream side (left side in FIGS. 3 and 4) of the driven roller 4 in the moving direction of the transfer belt 6 so as to contact the inside of the transfer belt 6. The bias roller 11 constitutes a contact electrode for applying a charge having a polarity opposite to the charging polarity of the toner T on the photoconductor 3 to the transfer belt 6, and is connected to the high voltage power supply 12. In this embodiment, since the toner T having the positive polarity is used, the polarity of the transfer bias is negative.

The contact plate 13 is arranged in contact with the inner surface of the transfer belt 6 on the lower side of the transfer sheet 6 which is not the transfer sheet transporting surface and in the vicinity of the driven roller 4. It suppresses the injection of charges. The contact plate 13 is for detecting the current flowing on the transfer belt 6 as a feedback current, and the current supplied from the bias roller 11 is controlled by the detection of this current. Therefore, the contact plate 13 is connected to the transfer control plate 14 for setting the supply current to the bias roller 11 according to the detected current, and the transfer control plate 14 is connected to the high-voltage power supply 12. .

In the transfer / transport device 1 as described above, as shown in FIG. 4, the support 7 moves the transfer belt 6 closer to the photoconductor 3 as the transfer paper S is fed from the registration roller 10. A transfer nip portion B having a width of about 4 to 8 mm corresponding to the length of the transfer paper in the conveyance direction is formed between the transfer member and the photoconductor 3.

On the other hand, the surface of the photoconductor 3 is, for example, −
The toner is charged to 800 V, and as shown in FIG. 6, the toner T, which is positively charged, is electrostatically adsorbed to the surface and moves to the transfer nip portion. The photoconductor 3 is arranged in the vicinity of the photoconductor 3 before reaching the nip portion, and the surface potential is lowered by a pre-transfer charge eliminating lamp (PTL) 15 that weakens the charge on the surface of the photoconductor 3. In FIG. 6, the height of the charge is represented by the size of the circle, and the state in which the charge is reduced by the pre-transfer charge eliminating lamp 15 is shown smaller than the circle indicating before charge removal.

The toner T on the photosensitive member 3 is transferred onto the transfer sheet S by the transfer bias from the bias roller 11 located on the transfer belt 6 side in the transfer nip portion B shown in FIG. This transfer bias is -1.5 kv to -6.5.
It is applied from the high voltage power supply 12 in the range of kv.
This is because the transfer bias is variably set as a result of constant voltage control described later.

That is, in FIG. 3 and FIG.
The current value output from the power supply 12 is I₁And transfer belt
The feedback current value flowing from the contact plate 13 to the ground side via 6
The value when detected is I₂If both are₁-I₂= I_OUT (However, I_OUT: Constant) ・ ・ ・ ・ I so that the relationship of (1) can be obtained₁Control the value of. this is,
Changes in environmental conditions such as temperature and humidity, and manufactured products of the transfer belt 6.
Surface potential on the transfer paper S, regardless of variations in quality
V_PTo stabilize the transfer and eliminate changes in transfer efficiency
To do so. That is, the transfer belt 6 and the transfer belt
The current flowing through the copying paper S to the photoconductor 3 side is I_{OU T}As
By considering it, the surface resistance V on the transfer paper S is_Pof
Current to transfer belt 6 due to low resistance or high resistance
The change in the ease of flow affects the separation performance and transfer performance of the transfer paper S.
It is designed to prevent it from resonating. This embodiment
If I _OUTIs the transfer belt transport speed of 330 mm /
sec, effective bias roller length 310 mm, I
_OUT= 35μA ± 5μA, good transfer
Was obtained.

When the toner image is transferred from the photoconductor 3, the transfer paper S is also charged at the same time. Therefore, due to the relationship between the true charge of the transfer belt 6 and the polarization charge generated on the transfer paper S side, the transfer paper S is electrostatically adsorbed on the transfer belt 6 and the transfer paper can be separated from the photoconductor 3. . Further, this separation is promoted by the peeling operation by the stiffness of the transfer paper S itself utilizing the curvature separation of the photoconductor 3.
However, such electrostatic attraction makes it difficult to separate the transfer paper because a current easily flows to the photoconductor 3 in the case of high humidity due to a change in environmental conditions. Therefore, since the resistance value of the surface layer 6b of the transfer belt 6 shown in FIG. 5 is set to be slightly higher, the transfer of the true charge to the transfer sheet S at the transfer nip portion B is delayed, and further, The bias roller 11 is located downstream of the transfer nip portion B in the transfer paper conveyance direction. As a result, the transfer of the true charge from the transfer belt 6 to the transfer sheet S is delayed, and the transfer sheet S and the photoconductor 3
It is designed to avoid an electrostatic attraction relationship between and.

Delaying the transfer of the true charge used in this case means that no charge is generated to the transfer sheet S on the upstream side until the transfer sheet S reaches the transfer nip portion B on the photoconductor 6 side. There is. As a result, the transfer sheet S is prevented from being wound around the photoconductor 3, and also the separation failure of the transfer sheet S from the photoconductor 3 is prevented.

Further, it is better to select a transfer belt 6 which has a small resistance change due to environmental changes. As a conductive material for controlling the resistance, carbon, zinc oxide or the like is added in an appropriate amount to form an elastic belt. When a rubber belt is used, it is desired to select a material such as chloroprene rubber, EPDM rubber, silicone rubber, and epichlorohydrin rubber that has a low hygroscopic property and a stable resistance value. In addition,
The value of the current I _OUT flowing to the side of the photoconductor 3 is not unique and can be reduced, for example, when the transport speed is slow, and conversely, when the transport speed is fast or the pre-transfer charge elimination lamp 1 is used.
If 5 is not used, it will be increased.

On the other hand, the transfer sheet S that has passed through the transfer nip portion B
Is conveyed in accordance with the movement of the transfer belt 6, and the curvature separation is performed by the drive roller 5. Therefore, the drive roller 5
Has a diameter of 16 mm or less. Furthermore, when such a drive roller 5 is used, fine quality 45K paper
(Stiffness transverse 21 [cm ^3/100]) experimental result that separation is possible of is obtained.

The transfer sheet S separated from the transfer belt 6 by the driving roller 5 is guided by the guide plate and conveyed between the heating roller 17a and the pad roller 17b which constitute the fixing section 17. In the fixing unit 17, the toner on the transfer sheet S is heated and melted and pressure-bonded to the transfer sheet S to fix the toner on the transfer sheet S. When the transfer of the toner image onto the transfer sheet S and the separation of the transfer belt 6 are completed, the contact / separation lever 9 is released in response to the release of the excitation of the DC solenoid 8, and the support 7 or the photoconductor 3 is released.
Away from.

As shown in FIGS. 3 and 4, the cleaning device 16 includes a bias cleaning roller 16A as a toner removing means. The bias cleaning roller 16A is a member to which a bias is applied. The bias cleaning roller 16A is rotatably supported by the support plate 7, is in sliding contact with the transfer belt 6, and is connected to the high-voltage power supply 12, and has a polarity opposite to that of the toner T during cleaning. A bias of polarity is applied. In FIGS. 3 and 4, the bias cleaning roller 16A is used as the toner removing means.
As shown in FIG. 1 and FIG. 12, the cleaning blade 16C that is not biased and the brush 16 as a brush-like member
It may be D.

The transfer belt 6, which is rubbed by the bias cleaning roller 16A, has a low friction coefficient in order to prevent an increase in driving force due to an increase in rubbing resistance. . It is coated with polyvinylidene fluoride, tetrafluoroethylene or the like. Further, the toner T and paper dust that are cleaned from the surface of the transfer belt 6 are scraped off by the blade 19 that is in sliding contact with the bias cleaning roller 16A, and the blade 1
A recovery screw 16B disposed below 9 collects a waste toner recovery container (not shown) from the main body 1A.

On the other hand, the transfer belt 6 described above, as shown in FIG. 5, is made of carbon-added chloroprene rubber.
It has a two-layer structure of an inner surface layer 6a composed of a rubber belt molded to a thickness of 0.4 mm through a kneading step, a molding step and a polishing step, and a surface layer 6a which is a foam film layer made of urethane foam. The inner surface layer 6a has a volume resistance of 1 × 10 ⁸ Ω · cm.
It has been.

The surface layer 6a is made into a foamed film layer having foam cells 18 by mixing a foaming agent in urethane as a base material, applying the foaming agent to a rubber belt constituting the inner surface layer 6a, and heating and curing in a heating step. ing. The size of the foam cell 18 can be adjusted by the amount of the foaming agent. Therefore, the upper surface of the surface layer 6a is, as shown in FIG.
Are exposed, and this exposure causes unevenness.

The transfer belt 6 having such a foamed film layer as the surface layer 6b was applied to the transfer / conveying belt device 1, and the applicant of the present invention conducted a transfer paper backside stain test. The results shown in Table 1 below. was gotten. In Table 1, ∘ indicates a state without back stain, Δ indicates a state where back stain is slightly conspicuous, and × indicates a state where there is much back stain. In the test, the size of the foam cell 18 of the urethane foam film layer (referred to as “foam urethane coat” in Table 1) forming the surface layer 6b of the transfer belt 6 is set to 7 μm.
m, 15 μm, 30 μm, 60 μm, a plurality of transfer belts 6, and a cleaning method using a bias cleaning roller 16A, a cleaning blade 16C, and a brush 16D as toner removing means, and a case where the surface layer 6b is foamed. And a belt having a urethane layer without a rubber layer were provided, and the combination was carried out as shown by from 1 in Table 1. The urethane layer without foaming is formed on the surface of the inner surface layer 6a,
Hirono Kagaku Co., Ltd. C-230U base agent 100 parts by weight, C
Molded to a layer thickness of 10 μm with urethane mixed with 30 parts by weight of −230 U curing agent. The toner T used has an average particle size of 10 μm.

[0027]

[Table 1]

In Table 1, when the cleaning method is not used (,,,,), when the surface layer 6b is a foam layer, the back smearing is slower and the toner It can be seen that in the case where the foamed cell diameter is larger than the T average particle diameter of 10 μm, the occurrence of back stain is further delayed. This is because, as shown in FIG. 7, the toner T is held in the foam cells 18 exposed on the surface layer 6b formed of the foam film, so that the toner T adheres less to the transfer paper S. Further, when the diameter of the foamed cells 18 is larger than the toner T average particle diameter of 10 μm, the back stain is slow to occur. As shown in FIG. 9, the toner T held in one foamed cell 18 is retained. It is considered that this is because the amount of

Next, when the cleaning system (,,,) is used, as shown in even if the surface layer 6b is a foam film layer, when the cleaning system is the cleaning blade 16D, the back stain is caused. Appears relatively early. This means that the surface layer 6b
Becomes a foam film layer, so that as shown in FIG.
It is conceivable that the cleaning blade 16D cannot completely remove the toner T that has entered the foam cell 18, resulting in insufficient cleaning.

Further, it can be seen that the back stain is generated more slowly when the bias cleaning or the brush cleaning is performed than when the cleaning blade 16D is used. In the case of bias cleaning, the back stain is slow to occur because the toner T that has entered the foam cell 18 from the foam cell 18 to the roller side due to the bias of the opposite polarity to the toner from the bias cleaning roller 16A as shown in FIG. Since it is electrostatically attracted to the transfer belt 6, the transfer belt 6 is satisfactorily cleaned,
This is because less toner T remains on the transfer belt 6. This is because in the case of cleaning with the brush member, the toner T that has entered the foam cells 18 is scraped out by the brush 16D and the transfer belt 6 is sufficiently cleaned. Further, since the transfer belt 6 is properly cleaned, the replacement cycle of the belt is extended.

As described above, when at least the surface layer 6b of the transfer belt 6 is formed of the foam layer film, the toner T adhering to the transfer belt 6 can be firmly captured on the belt.
Adhesion of the toner T to the back surface of the transfer sheet S is reduced. Further, by setting the foaming cells 18 larger than the average particle diameter of the toner T, a large amount of the toner T is captured in one cell, so that the adhesion of the toner T to the back surface of the transfer paper S can be more reliably reduced. It Also, the bias cleaning roller 16A
When the transfer belt 6 having the foamed film layer is cleaned by using a toner removing unit such as a brush or a brush 16D, compared with the case where the cleaning blade 16C is used for cleaning.
The transfer belt 6 is cleaned well, and the transfer paper S
Adhesion of the toner T to the back surface is reduced.

When the surface layer 6b is made of a foam and is a foamed film layer, a thin film 6c of several microns called a skin layer is generated on the upper surface of the surface layer 6b as shown in FIG. 10 depending on molding conditions and materials. The foam cells 18 may not be exposed on the upper surface of the layer 6b. Therefore, after the step of applying urethane foam to the inner surface layer 6a and curing it by heating, a processing step of grinding or polishing the molded foam film layer is carried out to polish the surface layer 6b which is the foam film layer. By carrying out the processing steps in this way, the thin film 6c can be removed. Therefore, the foam cells 18 are exposed on the surface layer 6b to capture the toner T, and the molding conditions of the foam film layer and the range of materials used are widened. In the test described above, urethane was used as the base material of the foamed film layer, but it has been confirmed that the same effect can be obtained by using acrylic or another material as the base material. Further, in the above-described embodiment, the transfer conveyor belt apparatus 1 using the transfer bias to the transfer bell 6 by the bias roller 11 is used. As a result of application, it was possible to obtain a result substantially similar to the back stain result in Table 1.

[0033]

According to the first aspect of the invention, the toner adhering to the image carrier is caught on the transfer belt surface by being caught by the foamed portion on the surface of the transfer belt. It is possible to reduce the movement of toner and reduce the back stain on the transfer material. According to the second aspect of the present invention, since the foamed cell diameter of the foamed film layer is formed larger than the average particle diameter of the toner, a large amount of toner is reliably captured in one foamed cell, and the transfer material is transferred from the belt surface. It is possible to reduce the movement of the toner to the back side and further reduce the back stain on the transfer material. According to the third aspect of the present invention, the toner removing unit is formed of a member to which a bias having a polarity opposite to the polarity of the toner is applied or a brush-shaped member to which the bias is not applied. Since the cleaning performance for the surface is improved, the amount of toner existing on the transfer belt is reduced, and the back stain on the transfer material can be further reduced. Further, since the cleaning performance is improved, the replacement cycle of the transfer belt is extended, which leads to the durability of the belt. According to the invention of claim 4, since the foamed film layer formed on the surface of the transfer belt is ground or polished, the foamed cells are surely exposed on the belt surface even when the foamed cells are not exposed on the foamed film layer. Can be made. Therefore, the toner can be captured on the transfer belt to reduce the back stain on the transfer material, and the belt manufacturing process and the selection range of the material of the foamed film layer can be widened.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a transfer / transport belt device.

FIG. 2 is a plan view showing a schematic configuration of a transfer belt unit.

FIG. 3 is an arrangement diagram showing a schematic configuration of a transfer / conveyance belt device.

FIG. 4 is an arrangement diagram showing an operation of the transfer / conveying belt device shown in FIG. 3 during transfer.

FIG. 5 is a partially enlarged sectional view of a transfer belt.

FIG. 6 is an enlarged view showing a transfer operation of toner particles.

FIG. 7 is a cross-sectional view showing the relationship between the surface layer of the transfer belt and the toner.

FIG. 8 is an enlarged view showing a cleaning state of the transfer belt.

FIG. 9 is an enlarged cross-sectional view showing a modified example of the transfer belt.

FIG. 10 is a cross-sectional view of a transfer belt having a skin layer formed thereon.

FIG. 11 is an arrangement view showing a schematic configuration of a transfer / transport belt device in which a toner removing unit is modified.

FIG. 12 is an arrangement view showing a schematic configuration of a transfer / transport belt device in which a toner removing unit is modified.

[Explanation of symbols]

 1 Transfer / Conveyor Belt Device 3 Image Carrier 6 Transfer Belt 6b Foamed Film Layers 16A and 16D Toner Removal Unit 18 Foamed Cell S Transfer Material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Ishii 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Satoshi Takano 1-3-6 Nakamagome, Ota-ku, Tokyo -In stock company Ricoh (72) Inventor Akio Eda 1-3-3 Nakamagome, Ota-ku, Tokyo-In stock company Ricoh (72) Haruji Mizuishi 1-3-6 Nakamagome-Tokyo, Ota-ku-Stock Company Ricoh

Claims (4)

[Claims] 1. A transfer / transport belt device having a transfer belt for electrostatically transferring toner formed on an image carrier onto a transfer material and transporting the transfer material, wherein the surface of the transfer belt is a foam film. A transfer and transport belt device, which is formed of layers. 2. The transfer / conveying belt device according to claim 1, wherein the foamed cell diameter of the foamed film layer is larger than the average particle diameter of the toner. 3. The transfer / conveying belt according to claim 1, further comprising a toner removing unit composed of a member to which a bias having a polarity opposite to that of the toner is applied or a brush-shaped member to which the bias is not applied. apparatus. 4. A method for producing a transfer belt, which comprises forming a foamed film layer on the surface of the transfer belt and then subjecting the transfer belt to a processing step of grinding or polishing the foamed film layer.