JP5002959B2 - Semiconductive belt and image forming apparatus provided with the semiconductive belt - Google Patents

Description

  The present invention relates to a semiconductive belt used for electrophotography and an electrostatic recording program in an image forming apparatus such as an electrophotographic copying machine and a printer, and an image forming apparatus including the semiconductive belt.

As a conventional image forming apparatus, for example, a photosensitive drum (image forming carrier) and a visible image formed on the photosensitive drum, which is arranged so as to be able to contact and roll with respect to the photosensitive drum, are formed on paper. A transfer roller or a transfer belt for transferring to a recording medium such as the above is known (for example, see Patent Document 1).
On the other hand, as a color image forming apparatus, for example, an intermediate transfer belt as an intermediate transfer member is disposed opposite to a photosensitive drum, and toner images of respective color components are sequentially primary transferred onto the intermediate transfer belt, and then collectively from the intermediate transfer belt. What is already transferred to a recording medium such as paper is already known. Compared with a direct transfer type image forming apparatus, a copying machine using an intermediate transfer system has an advantage that it can transfer envelopes, postcards, label papers and cardboards regardless of the size.

In the image forming apparatus using the intermediate transfer method, in order to increase the transfer efficiency in the primary transfer unit, a peripheral speed difference is provided between the photosensitive drum and the intermediate transfer member, and the toner and the photosensitive drum are mechanically separated. There is a method of breaking the adhesion force of the toner by applying a shear force between the two. However, for example, if the peripheral speed of the intermediate transfer belt is made faster than the peripheral speed of the photosensitive drum in the primary transfer portion, the intermediate transfer belt pulls the photosensitive drum due to electrostatic adsorption force, so that the rotational speed of the photosensitive drum varies. This may cause banding and color misregistration.
As described above, when the peripheral speed difference is increased in order to increase the transfer efficiency, the countermeasure for improving the transfer efficiency and the countermeasure for preventing the image quality defect are contradictory, and it is difficult to achieve both.

In order to solve this problem, for example, an intermediate transfer belt having elasticity is stretched over a plurality of stretching rolls, and the contact area between the intermediate transfer belt and the photosensitive drum is increased, so that a conventional image forming apparatus is used. Compared to the above, it has become possible to realize higher transfer efficiency with higher image quality (see, for example, Patent Document 2).
However, when the intermediate transfer belt is stretched and used in this way, a change in belt resistance occurs due to the expansion rate, and a constant image cannot be obtained. In particular, in the case of a belt having a high elongation rate and a large belt circumferential elongation, a resistance change due to a decrease in the elongation rate over time occurs in addition to a resistance change due to the elongation.
In order to solve this problem, for example, there is a method of keeping the belt resistance constant by detecting the extension or resistance of the belt on the apparatus side and changing the belt tension based on the detection result (for example, patents). Reference 3). However, in this method, it is necessary to add a device for reading the belt extension and resistance and a mechanism for keeping the belt tension constant, and the cost increases. In addition, during operation of the image forming apparatus, there is a problem that an image cannot be output while it is necessary to read the extension and resistance and adjust the tension.

Further, as a method of reading the belt resistance and controlling the resistance, there is a method of controlling the resistance by heating the belt (see, for example, Patent Document 4).
However, in this method, it is necessary to add a device for heating the belt in order to control the resistance in addition to the device for reading the belt resistance, which increases the cost.
JP-A-63-301960 JP 2003-84581 A JP-A-9-84581 JP 2002-49247 A

Therefore, the present invention aims to solve the conventional problems and achieve the following object.
In other words, an object of the present invention is to provide a structure in which a protective layer made of a resin is provided on an elastic base material, and even if it is used after being stretched, it is possible to suppress deterioration in transfer performance over time. It is to provide a conductive belt.
Another object of the present invention is to provide an image forming apparatus capable of stably obtaining a good transfer image by including the semiconductive belt of the present invention.

The above-mentioned subject is achieved by the following present invention.
That is, the present invention
<1> It has a base material that has been vulcanized in a state of containing an elastic body and stretched under a condition of an elongation rate of 20% or more, and a protective layer provided on the base material, and has a volume when not stretched. The resistivity is in the range of 10 ⁷ to 10 ¹¹ Ωcm, and the difference in the common logarithmic value of the volume resistivity between no elongation and 5% elongation is 0.8 (log Ωcm) or less. It is a semiconductive belt.

  <2> An image forming apparatus comprising the semiconductive belt according to <1> as an intermediate transfer belt or a paper transport belt.

  <3> The semiconductive belt according to <1> is provided as an intermediate transfer belt, the intermediate transfer belt is stretched around a plurality of stretching rolls, and is arranged in contact along the shape of the image bearing member. An image forming apparatus in which one of the body and the intermediate transfer belt is used as a drive source and the other is driven to rotate.

  <4> The image forming apparatus according to <2> or <3>, wherein the semiconductive belt is used at an elongation rate of 1 to 10%.

ADVANTAGE OF THE INVENTION According to this invention, even if it extends | stretches and uses, the semiconductive belt which can suppress the fall of a transfer performance with time can be provided.
Further, according to the present invention, it is possible to provide an image forming apparatus capable of stably obtaining a good transfer image by including the semiconductive belt of the present invention.

  Hereinafter, in describing the present invention in detail, first, the intermediate transfer belt of the present invention will be described in detail, and then the image forming apparatus of the present invention will be described.

<Semiconductive belt>
The semiconductive belt of the present invention has a base material that contains an elastic body and is vulcanized in a state of being stretched under an elongation rate of 20% or more and a protective layer provided on the base material. The volume resistivity when not stretched is in the range of 10 ⁷ to 10 ¹¹ Ωcm, and the difference in the common logarithm of the volume resistivity between when no stretch and 5% stretch is 0.8 (log Ωcm) or less. It is characterized by being.
As described above, even when the semiconductive belt of the present invention is stretched, the change in volume resistivity is small. Therefore, the semiconductive belt is installed in the image forming apparatus and the stretched state is maintained. Even if it is continued, it is possible to suppress a decrease in transfer efficiency over time.
On the other hand, if the amount of change in volume resistivity exceeds 0.8 (log Ωcm), when an image is formed by an image forming apparatus equipped with the belt, the transfer performance is not stable, and image defects occur over time. End up.

-Volume resistivity of semiconductive belt-
In the semiconductive belt of the present invention, it is essential that the difference in the common logarithmic value of the volume resistivity between non-stretched and 5% stretched is 0.8 (log Ωcm), and more stable transfer efficiency is obtained. For this purpose, it is preferably 0.6 (log Ωcm) or less.
Here, the measuring method of the change amount of the volume resistivity in the present invention will be described.
First, “when not stretched” refers to a state where no external stress is applied to the semiconductive belt, and “when stretched at 5%” refers to a state where the semiconductive belt is not surrounded. It refers to the state of 5% extension in the direction.
More specifically, two metal shafts are put on the inner peripheral surface of the semiconductive belt, and the two metal shafts are properly positioned so that the inner peripheral length of the belt expands by 5% with respect to the non-stretched state. Refers to the state of being extended by 5%.

Hereinafter, the volume resistivity measuring method in the present invention will be described.
The volume resistivity was measured according to JIS K6911 (1995) using a circular electrode (for example, Hiresta UPMCP-450 type UR probe manufactured by Dia Instruments Co., Ltd.). A method for measuring volume resistivity will be described with reference to FIG. FIG. 1 shows an example of a circular electrode, where (a) is a top view and (b) is an XX cross-sectional view. The circular electrode shown in FIG. 1 includes a first voltage application electrode A ′ and a second voltage application electrode B ′. The first voltage application electrode A ′ has a cylindrical electrode part C ′ and a cylindrical shape having an inner diameter larger than the outer diameter of the cylindrical electrode part C ′ and surrounding the cylindrical electrode part C ′ at a constant interval. Ring-shaped electrode portion D ′. The semiconductive belt b is sandwiched between the cylindrical electrode portion C ′ and the ring-shaped electrode portion D ′ and the second voltage application electrode B ′ in the first voltage application electrode A ′, and the first voltage application electrode A ′. The current I (A) that flows when the voltage V (V) is applied between the cylindrical electrode portion C ′ and the second voltage application electrode B ′ is measured, and the volume of the semiconductive belt b is calculated by the following equation. The resistivity ρv (Ωcm) can be calculated. Here, in the following formula, t represents the thickness of the semiconductive belt b.
Formula: ρv = 19.6 × (V / I) × t
In the measurement, under a 22 ° C./55% RH environment, a voltage of 100 (V) is applied between the cylindrical electrode portion C ′ and the second voltage application electrode B ′ in the first voltage application electrode A ′. It was determined from the current value after 2 seconds. The average value measured for a total of 24 points of 3 points in the length direction and 8 points in the circumferential direction of the prepared base material was defined as the volume resistivity of the semiconductive belt.

In the semiconductive belt of the present invention, “semiconductive” means that the volume resistivity of the belt in an unstretched state is in the range of 10 ⁷ to 10 ¹¹ Ωcm. Since the volume resistivity is in this range, preferable transfer performance can be obtained.
The semiconductive belt may be a seamless endless belt or a seamless endless belt.

-Layer structure of semiconductive belt-
Next, the configuration of the intermediate transfer belt of the present invention will be described. As shown in FIG. 2, the semiconductive belt of the present invention includes a belt base material 101 containing an elastic body and a protective layer 102 provided to cover the surface of the base material 101. In addition, you may provide the protective layer 102 on both surfaces of the base material 101 as needed.

  The belt substrate 101 is a layer configured to contain an elastic body (elastic material), and it is preferable that a conductive agent is further dispersed.

  As the material forming the elastic material, there is a diene-based or non-diene-based rubber elastic body, and the material of the rubber elastic body may be either solid or liquid, such as acrylic rubber, isoprene rubber, butadiene rubber, Examples include ethylene-propylene copolymer rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, epichlorohydrin copolymer rubber, urethane rubber, silicone rubber, butyl rubber, chloroprene rubber, norbornene, and hydrogenated polybutadiene rubber. Among these, ethylene- More preferred are propylene copolymer rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, epichlorohydrin copolymer rubber, and chloroprene rubber. One or more of the above elastic materials can be used in a blend. If necessary, materials that can be usually added to rubber, such as softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, anti-aging agents, and fillers such as silica and calcium carbonate, may be added.

  As the conductive agent, conductive or semiconductive fine powder can be used, and there is no particular limitation as long as a desired electric resistance can be stably obtained. However, carbon black such as ketjen black and acetylene black, aluminum and the like Examples thereof include metals such as nickel, conductive metal oxides such as tin oxide, and potassium titanate. Among these, carbon black and conductive metal oxides are particularly preferable. These may be used alone or in combination.

  The content of the conductive agent is preferably 10 to 50 parts by mass with respect to 100 parts by mass of the elastic material (rubber elastic material) in order to control the resistance value of the semiconductive belt. It is more preferable to contain a mass part, and it is still more preferable to contain 20-40 mass parts.

The thickness of the belt base material 101 varies depending on the use of the semiconductive belt, the material to be used, and the composition, but is usually preferably in the range of 300 to 900 μm, more preferably in the range of 300 to 800 μm. Preferably, it is in the range of 400 to 700 μm.
If the thickness of the belt base material is less than 300 μm, the belt strength may not be sufficient and may break due to rotation or the like. If it exceeds 900 μm, the semiconductive belt may become unusable due to increased resistance and hardness. is there.

The protective layer 102 is a layer that is provided so that the back surface thereof is in contact with the surface of the substrate 101 and constitutes the outermost surface of the semiconductive belt.
Examples of the constituent material of the protective layer 102 include urethane resin, polyester, phenol resin, acrylic resin, polyurethane, epoxy resin, and cellulose.
Among these, urethane resin is preferable from the viewpoint of the hardness of the semiconductive belt.

The protective layer 102 may contain conductive or semiconductive fine powder. As the particulate conductive agent, those having a particle size of 3 μm or less and a volume resistivity of 1 × 10 ⁹ Ωcm or less are desirable. For example, fine particles made of metal oxides such as tin oxide, titanium oxide, and zinc oxide, or alloys thereof, or carbon black such as ketjen black and acetylene black can be used.
In addition, the addition amount of the conductive or semiconductive fine powder is 0 to 100 parts by mass of the paint main raw material used when forming the protective layer in order to control the resistance value of the semiconductive belt. The content is preferably 30% by mass, more preferably 0 to 20% by mass, and still more preferably 0 to 15% by mass.
Further, a fluorine-based or silicone-based resin or fine particles may be added to the protective layer 102.
Furthermore, a coupling agent may be added to improve the adhesion with the substrate 101.

The thickness of the protective layer 102 is preferably 1 μm or more and 20 μm or less, and more preferably 2 μm or more and 15 μm or less. If the thickness of the protective layer is less than 1 μm, the surface layer may be lost due to wear, and if it exceeds 20 μm, the crack width increases and crack ghost cannot be suppressed.
The thickness of the protective layer 102 can be controlled by the coating amount on the base material 101.

-Manufacture of semiconductive belts-
In forming the semiconductive belt of the present invention, a known method can be appropriately selected and used. In particular, the belt base material 101 is preferably a method in which an extruded material is coated on a metal pipe while being stretched and vulcanized to form an endless belt. At that time, elongation rate, Ru der 1.2 times (20%) or more. When the elongation rate is less than 1.2 times (20%), when the obtained semiconductive belt is stretched and used, an increase in volume resistivity is not suppressed, and when it is used in an image forming apparatus. , Image quality defects due to transfer defects will occur. From the viewpoint of manufacturing operation, the upper limit of the elongation ratio of the extruded material is about 3.0 times (300%).
Here, the elongation rate is determined from the ratio between the inner diameter of the extruded semiconductive belt and the outer diameter of the metal pipe used during vulcanization.
The semiconductive belt of the present invention can be produced by forming a protective layer by a coating method on the surface of the belt substrate thus obtained.

Moreover, the semiconductive belt of this invention can also be produced by the following method.
That is, the semiconductive belt of the present invention can also be produced by performing peroxide crosslinking, forming a belt base material by adding an additive, and forming a protective layer on the surface thereof by a coating method.

-Physical properties of intermediate transfer belt-
The semiconductive belt of the present invention preferably has a surface roughness Rz (10-point average roughness) specified in JIS-B0601 (2001) of 10 μm or less, more preferably 8 μm or less. The lower limit is not particularly limited, but is preferably 1.0 μm or more from the viewpoint of tackiness with the photosensitive drum.
The surface roughness of the belt can be adjusted to the above range by controlling the polishing conditions when producing the substrate (belt substrate).

In addition, the semiconductive belt of the present invention preferably has a hardness defined in JIS-K6253 (1997) of 80 degrees or less from the viewpoint of normal contact with the photosensitive drum in the image forming apparatus, and 75 degrees. The following is more preferable.
Furthermore, the semiconductive belt of the present invention preferably has a permanent elongation of 10% or less as defined in JIS-K6262 (1997) from the viewpoint of normal contact with the photosensitive drum in the image forming apparatus. % Or less is preferable.
The hardness can be measured in accordance with JIS-K6253 (1997), and the permanent elongation can be measured in accordance with JIS-K6262 (1997).

<Image forming apparatus>
Next, the image forming apparatus of the present invention will be described in detail with reference to the drawings.
The image forming apparatus of the present invention includes the above-described semiconductive belt of the present invention. The semiconductive belt is preferably used as an intermediate transfer belt or a paper transport belt in the image forming apparatus.
Note that when the image forming apparatus is provided with the semiconductive belt of the present invention as an intermediate transfer belt, the intermediate transfer belt is stretched around a plurality of stretching rolls, and is arranged in contact with the shape of the image carrier. It is a preferable aspect that the image forming apparatus has a configuration in which one of the carrier and the intermediate transfer belt is used as a drive source and the other is driven to rotate.
First, an image forming apparatus (an image forming apparatus of the present invention) provided with the semiconductive belt of the present invention as an intermediate transfer belt will be described.

FIG. 3 is a schematic configuration diagram showing an embodiment of the image forming apparatus of the present invention.
In FIG. 3, the image forming apparatus of the present invention includes a photosensitive drum (image carrier) 10 and a shape of the photosensitive drum 10 in a certain area on the photosensitive drum 10 in order to transfer a toner image from the photosensitive drum 10. And an intermediate transfer belt 20 in contact with each other. 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, black, yellow, magenta, cyan) on the charged photosensitive drum 10, and each color component latent image formed on the photosensitive drum 10. A rotary developing device 13 that visualizes an image with each color component toner, an intermediate transfer belt 20, and a cleaning device 17 that cleans residual toner on the photosensitive drum 10 are disposed.

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 by light. For example, a print head using an LED is used, but the present invention is not limited to this, and a print head using an EL. However, 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 in which the respective color component toners are accommodated. For example, each color component toner is placed on a portion of the photosensitive drum 10 where the potential is reduced by exposure. The toner to be used is not particularly limited in shape, particle size, etc., and any toner can be used as long as it is accurately placed on the electrostatic latent image on the photosensitive drum 10, From the viewpoint of obtaining good image quality, it is preferable to use a spherical toner.
In this example, the rotary developing device 13 is used, but four developing devices may be used.

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, for example, spherical toner is used with high transfer efficiency.

In the present embodiment, the intermediate transfer belt 20 is stretched around four stretching rolls 21 to 24, and is disposed on the surface of the photosensitive drum 10 positioned between the rotary developing device 13 and the cleaning device 17. Only a predetermined contact area is arranged in close contact with each other.
Of the four tension rolls 21 to 24 of the intermediate transfer belt 20, the tension roll 21 positioned on the upstream side of the transfer position functions as, for example, a drive roll, and the winding angle of the intermediate transfer belt 20 is the largest. Is set. Further, the tension roll 22 positioned on the downstream side of the transfer position is a driven roll and regulates a contact area with the photosensitive drum 10. Further, the stretching roll 23 located downstream thereof is a driven roll, and also serves as a back roll (grounded in this example) for secondary transfer. Is a driven roll, for example, also serving as a backup roll for the belt cleaning device 27.
In this example, the sizes of the four tension rolls 21 to 24 may be appropriately selected.

In this example, since the intermediate transfer belt 20 and the photosensitive drum (image carrier) 10 are disposed in contact with each other over a relatively wide range along the circumferential surface, the intermediate transfer belt 20 and the photosensitive drum 10 are arranged. It is possible to take a system in which one of the driving sources is driven and the other is driven to rotate. For example, the intermediate transfer belt 20 can be driven to rotate using the photosensitive drum 10 as a drive source. In the case of this method, one drive mechanism can be omitted, and the apparatus can be reduced in size and cost.
Further, the intermediate transfer belt 20 and the photosensitive drum 10 may be driven by separate drive systems.

  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. Has been. Further, a secondary transfer roll 30 as a secondary transfer device is disposed as a backup roll of the stretching roll 23 at a portion facing the stretching roll 23 of the intermediate transfer belt 20. For example, the secondary transfer roll It is preferable that a predetermined secondary transfer bias is applied to 30 and the stretching roll 23 that also serves as a backup roll is grounded.

  A recording material 40 such as paper is accommodated in a supply tray 41, supplied by a feed roll 42, and then guided to a secondary transfer site via a transport roll 43 and a resist roll 44, and a fixing roll 46 and a pressure roll. 47 is conveyed to a fixing device 45 having the number 47.

  Next, the operation of the image forming apparatus of the present invention shown in FIG. 3 will be described. The respective color component toner images are sequentially formed on the photosensitive drum 10, sequentially transferred to the intermediate transfer belt 20 via the contact area (primary transfer position), and then collectively transferred to the recording material 40 at the secondary transfer position. In such an image forming process, the photosensitive drum 10 and the intermediate transfer belt 20 are arranged in contact with each other in a relatively wide contact area and are elastically pressed by the intermediate transfer belt 20 having elasticity. The nip (tack) surface pressure between the body drum 10 and the intermediate transfer belt 20 is not so high, and the toner image is wrapped by the elastic intermediate transfer belt 20 so that the toner image on the photoreceptor drum 10 is encased. Is primarily transferred to the intermediate transfer belt 20 side. At this time, the transfer image onto the intermediate transfer belt 20 is free from image quality defects such as holo characters due to a large nip surface pressure, and is transferred with high transfer efficiency. Therefore, the color image quality on the recording material 40 is kept extremely good. It is.

Next, an image forming apparatus (an image forming apparatus according to the present invention) provided with the semiconductive belt according to the present invention as an intermediate transfer belt or a sheet conveying belt will be described.
FIG. 4 is a schematic configuration diagram showing another embodiment of the image forming apparatus of the present invention.
As shown in FIG. 4, the image forming apparatus of the present invention includes a photosensitive drum (image carrier) 6 and a semiconductive belt 1 facing the photosensitive drum (image carrier) 6, and a toner image formed on the photosensitive drum 6. The image is transferred to the recording material 7 ′ on the semiconductive belt (intermediate transfer belt) 1 or the semiconductive belt (transfer conveyance belt) 1 ′.

  Here, in an embodiment in which the semiconductive belt 1 is used as an intermediate transfer belt, as shown in FIG. 4, after the toner image on the photosensitive drum 6 is primarily transferred to the intermediate transfer belt 1 by the primary transfer device 8a, The toner image on the intermediate transfer belt 1 is secondarily transferred to the recording material 7 such as paper by the secondary transfer device 8b.

  On the other hand, in the embodiment in which the semiconductive belt 1 is used as a transfer / conveyance belt, as shown in FIG. 4, after the recording material 7 ′ is held on the transfer / conveyance belt 1 ′, the toner image on the photosensitive drum 6 is transferred. The image is transferred to the recording material 7 ′ on the transfer conveyance belt 1 ′ by the apparatus 8.

  In the image forming apparatus shown in FIG. 4, it is preferable that the semiconductive belt 1 is stretched around a plurality of stretching rolls 9 and is arranged in contact with the drum-shaped photosensitive drum 6.

  According to this aspect, the semiconductive belt 1 is made to conform to the shape of the photosensitive drum 6 as much as possible, thereby eliminating discharge due to useless gaps before and after the nip area at the time of transfer and preventing the toner image from scattering. In addition, it is advantageous for the paper peeling performance from the photosensitive drum.

Further, in the image forming apparatus shown in FIG. 4, it is preferable that one of the photosensitive drum (image carrier) 6 and the semiconductive belt 1 is used as a drive source and the other is driven to rotate.
By adopting such a driving configuration, one of the driving mechanisms can be omitted, and the driving cost can be reduced correspondingly, and the driving interference between the semiconductive belt 1 and the photosensitive drum 6 can be reduced. Variation factors such as thickness variation of the conductive belt 1 and feed variation in the process direction can be excluded.

In the image forming apparatus of the present invention, the semiconductive belt is extended and used in order to suppress the undulation of the belt and the instability of the nip with the photosensitive drum (image carrier) or transfer roll. It is preferable. In particular, as described above, in order to follow and rotate the image carrier and the semiconductive belt, a certain degree of extension is required.
Therefore, in the image forming apparatus of the present invention, it is preferable to use the stretch ratio in the range of 1 to 10% with respect to the semiconductive belt of the present invention, and the stretch ratio in the range of 4 to 10% is more preferable. .
Here, if the stretch rate exceeds 10%, a crack may occur in the protective layer of the semiconductive belt, and a good image quality may not be obtained.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “part” represents “part by mass”.

<Example 1>
(Preparation of belt substrate)
75 parts by mass of polychloroprene rubber (ES-40, manufactured by Denki Kagaku Kogyo), 25 parts by mass of epichlorohydrin copolymer (Zeklon 3106, manufactured by Nippon Zeon), 30 parts by mass of carbon (Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.) Chain black EC (Asahi Carbon Co., Ltd.) 8 parts by mass, zinc oxide (Zinc Hana 1, Nippon Chemical Industry) 5 parts by mass, magnesium oxide (Kyowa Mag 150, Kyowa Chemical Industry Co., Ltd.) 5 parts by mass, process oil (Diana PW) -150, Idemitsu Kosan) 10 parts by mass, sulfur (# 200, Tsurumi Chemical Industries) 1 part by mass, vulcanization accelerator (Noxeller TS, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part by mass, and vulcanization accelerator (Noxeller) (DT, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.5 parts by mass was kneaded and then extrusion molded so as to have a thickness of 2.5 mm and a diameter of 90 mm. Thereafter, the metal pipe having a diameter of 140 mm was expanded and coated (elongation rate 56%), and steam vulcanization was performed in a vulcanization can at 150 ° C. for 1 hour. Further, the belt after vulcanization was finished to a thickness of 500 μm by grinding the front and back sides with a cylindrical grinder.

(Preparation of protective layer)
On the surface of the obtained belt base material, a coating solution in which 5 parts by mass of carbon black is added to 100 parts by mass of JLY-601 ESD (manufactured by Japan Atchison Co., Ltd.) is spray-coated so as to have a thickness of 5 μm. A protective layer was formed by heating at 0 ° C. for 30 minutes.
The volume resistivity of the obtained semiconductive belt was 5 × 10 ⁸ Ωcm.

<Example 2>
(Preparation of belt substrate)
75 parts by mass of polychloroprene rubber (ES-40, manufactured by Denki Kagaku Kogyo), 25 parts by mass of epichlorohydrin copolymer (Zeklon 3106, manufactured by Nippon Zeon), 27 parts by mass of carbon (Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.) Chain black EC (Asahi Carbon Co., Ltd.) 8 parts by mass, zinc oxide (Zinc Hana 1, Nippon Chemical Industry) 5 parts by mass, magnesium oxide (Kyowa Mag 150, Kyowa Chemical Industry Co., Ltd.) 5 parts by mass, process oil (Diana PW) -150, Idemitsu Kosan) 10 parts by mass, sulfur (# 200, Tsurumi Chemical Industries) 1 part by mass, vulcanization accelerator (Noxeller TS, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part by mass, and vulcanization accelerator (Noxeller) (DT, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) 0.5 parts by mass was kneaded, and extrusion molding was performed so that the inner diameter was 100 mm with a thickness of 2 mm. Thereafter, the metal pipe having an outer diameter of 140 mm was expanded and coated (elongation rate 40%), and steam vulcanization was performed in a vulcanization can at 150 ° C. for 1 hour. Further, the belt after vulcanization was finished to a thickness of 500 μm by grinding the front and back sides with a cylindrical grinder.

(Preparation of protective layer)
On the surface of the obtained belt base material, a coating solution in which 5 parts by mass of carbon black is added to 100 parts by mass of JLY-601 ESD (manufactured by Japan Atchison Co., Ltd.) is spray-coated so as to have a thickness of 5 μm. A protective layer was formed by heating at 0 ° C. for 30 minutes.
The volume resistivity of the obtained semiconductive belt was 5 × 10 ⁸ Ωcm.

<Example 3>
(Preparation of belt substrate)
75 parts by mass of polychloroprene rubber (ES-40, manufactured by Denki Kagaku Kogyo), 25 parts by mass of epichlorohydrin copolymer (Zeklon 3106, manufactured by Nippon Zeon), 25 parts by mass of carbon (Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.) Chain black EC (Asahi Carbon Co., Ltd.) 8 parts by mass, zinc oxide (Zinc Hana 1, Nippon Chemical Industry) 5 parts by mass, magnesium oxide (Kyowa Mag 150, Kyowa Chemical Industry Co., Ltd.) 5 parts by mass, process oil (Diana PW) -150, Idemitsu Kosan) 10 parts by mass, sulfur (# 200, Tsurumi Chemical Industries) 1 part by mass, vulcanization accelerator (Noxeller TS, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part by mass, and vulcanization accelerator (Noxeller) DT (manufactured by Ouchi Shinsei Chemical Co., Ltd.) was mixed with 0.5 parts by mass, and then extruded so that the inner diameter was 115 mm with a thickness of 1.5 mm. Thereafter, the metal pipe having an outer diameter of 140 mm was expanded and coated (elongation rate: 22%), and steam vulcanized in a vulcanization can at 150 ° C. for 1 hour. Further, the belt after vulcanization was finished to a thickness of 500 μm by grinding the front and back sides with a cylindrical grinder.

(Preparation of protective layer)
On the surface of the obtained belt base material, a coating solution in which 5 parts by mass of carbon black is added to 100 parts by mass of JLY-601 ESD (manufactured by Japan Atchison Co., Ltd.) is spray-coated so as to have a thickness of 5 μm. A protective layer was formed by heating at 0 ° C. for 30 minutes.
The volume resistivity of the obtained semiconductive belt was 5 × 10 ⁸ Ωcm.

<Example 4>
(Preparation of belt substrate)
75 parts by mass of polychloroprene rubber (ES-40, manufactured by Denki Kagaku Kogyo), 25 parts by mass of epichlorohydrin copolymer (Zeklon 3106, manufactured by Nippon Zeon), 25 parts by mass of carbon (Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.) Chain black EC (Asahi Carbon Co., Ltd.) 8 parts by mass, magnesium oxide (Kyowa Mag 150, manufactured by Kyowa Chemical Industry Co., Ltd.) 5 parts by mass, process oil (Diana PW-150, Idemitsu Kosan Co., Ltd.) 10 parts by mass, cross-linking agent (Perhexa V After kneading 4 parts by mass (-40, manufactured by NOF Corporation) and magnesium hydroxide (Kyowasui Mug, manufactured by Kyowa Chemical), extrusion molding was performed so that the inner diameter was 115 mm with a wall thickness of 1.5 mm. Thereafter, the metal pipe having an outer diameter of 140 mm was expanded and coated (elongation rate: 22%), and steam vulcanized in a vulcanization can at 150 ° C. for 1 hour. Further, the vulcanized belt was finished to a thickness of 500 μm by grinding the front side and the back side with a cylindrical grinder.

(Preparation of protective layer)
On the surface of the obtained belt base material, a coating solution in which 5 parts by mass of carbon black is added to 100 parts by mass of JLY-601 ESD (manufactured by Nippon Atson Co., Ltd.) is spray-coated so as to have a thickness of 5 μm. A protective layer was formed by heating at 0 ° C. for 30 minutes.
The volume resistivity of the obtained semiconductive belt was 5 × 10 ⁸ Ωcm.

<Comparative Example 1>
(Preparation of belt substrate)
75 parts by mass of polychloroprene rubber (ES-40, manufactured by Denki Kagaku Kogyo), 25 parts by mass of epichlorohydrin copolymer (Zeklon 3106, manufactured by Nippon Zeon), 20 parts by mass of carbon (Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.) Chain black EC (Asahi Carbon Co., Ltd.) 8 parts by mass, zinc oxide (Zinc Hana 1, Nippon Chemical Industry) 5 parts by mass, magnesium oxide (Kyowa Mag 150, Kyowa Chemical Industry Co., Ltd.) 5 parts by mass, process oil (Diana PW) -150, Idemitsu Kosan) 10 parts by mass, sulfur (# 200, Tsurumi Chemical Industries) 1 part by mass, vulcanization accelerator (Noxeller TS, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part by mass, and vulcanization accelerator (Noxeller) DT (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) was mixed with 0.5 parts by mass, and then extruded so that the inner diameter was 138 mm with a thickness of 1.0 mm. Thereafter, a metal pipe having an outer diameter of 140 mm was coated (elongation rate 1%), and steam vulcanization was performed in a vulcanizer at 150 degrees for 1 hour. Further, the belt after vulcanization was finished to a thickness of 500 μm by grinding the front and back sides with a cylindrical grinder.

(Preparation of protective layer)
On the surface of the obtained belt base material, a coating solution in which 5 parts by mass of carbon black is added to 100 parts by mass of JLY-601 ESD (manufactured by Nippon Atson Co., Ltd.) is spray-coated so as to have a thickness of 5 μm. A protective layer was formed by heating at 0 ° C. for 30 minutes.
The volume resistivity of the obtained semiconductive belt was 5 × 10 ⁸ Ωcm.

<Evaluation>
The semiconductive belts of Examples 1 to 4 and Comparative Example 1 were installed as an intermediate transfer belt in an image forming apparatus having the following configuration, and the transfer performance was evaluated by the following method. Note that the configuration of the image forming apparatus shown below is substantially the same as the configuration of the image forming apparatus shown in FIG.

-Photosensitive drum: OPC sensitive material-Process speed: 80mm / s
・ Developer: Developer of Docu Center Color 400CP manufactured by Fuji Xerox Co., Ltd. ・ Developer carrier: A 15 mm aluminum hollow pipe anodized ・ Image forming member: 0.5 mm thick SUS plate with a rubber hardness of 50 degrees Silicone rubber
Those set to the doctor method-Primary transfer device: φ15 mm, volume resistivity 10 ⁸ Ωcm,
Roll / secondary transfer device having a semiconductive sponge material layer: φ20 mm, volume resistivity 10 ⁸ Ωcm,
Roll / latent image potential provided with a foamable silicone rubber layer containing an ionic conductive agent: −100V
・ Background potential: -350V
Intermediate transfer belt: A semiconductive belt is stretched by 5% with a roll and stretched.
Intermediate transfer belt driven by photosensitive drum drive,
Contact width with photoconductor drum (nip width) 30 mm
・ Fixing device: φ40mm hollow type using SUS material with a thickness of 0.5mm ・ Heat lamp: Tungsten lamp with a rating of 650W ・ Pressure roll: A rubber layer with a thickness of 50mm on a SUS cylinder of φ30mm
Covered / Recording material: Fuji Xerox J paper

<Image quality evaluation>
For Examples 1 to 3 and Comparative Example 1, images were evaluated by the following methods.
Here, the image quality evaluation was performed on the initial image and the image after running 10,000 images with an image area coverage of 5% for ghost and mottle (density unevenness).
The evaluation results are summarized in Table 1.
In Table 1, the left side of “→” is the evaluation result for the initial image, and the right side of “→” is the evaluation result for the image after running 10,000 sheets.

(Ghost evaluation)
A pattern that continuously forms a 17 mm square solid image and a 50% halftone image in one image is output, and the presence or absence of light and shade differences in the halftone image portion below the photoreceptor circumference from the solid image is visually evaluated. did.
The evaluation index of ghost is as follows.
○: No difference in density △: Level where there is a difference in intensity, but there is no practical problem (within the allowable range)
X: There is a difference in light and shade.

(Motor rating)
Yellow, magenta, cyan, and black 100% solid images were output, and the image quality was visually evaluated.
The evaluation index of the mottle is as follows.
○: Density unevenness △: Density unevenness is observed, but there is no practical problem (within the allowable range)
×: Density unevenness

As is apparent from Table 1, the image forming apparatus provided with the semiconductive belt of the present invention as an intermediate transfer belt in which the volume resistivity change amount is 0.8 (log Ωcm) or less, regardless of the transfer current value. In both the initial image and the image after running 10,000 sheets, good results were obtained for both mottle and ghost. Thereby, it turns out that the fall of the transfer performance with time is suppressed.
Further, according to Table 1, it was found that the semiconductive belt of the present invention has a wide range of applicable transfer current values by obtaining similar results when the transfer current value is in the range of 9 to 15 μA. .
On the other hand, in the image forming apparatus provided with the semiconductive belt of Comparative Example 1, there was a problem in the mottle in the image after running 10,000 sheets.

<Example 5>
(Preparation of belt substrate)
75 parts by weight of polychloroprene rubber (ES-40, manufactured by Denki Kagaku Kogyo), 25 parts by weight of epichlorohydrin copolymer (Zeklon 3106, manufactured by Nippon Zeon), 25 parts by weight of carbon (Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.), kettle Chain black EC (Asahi Carbon Co., Ltd.) 8 parts by weight, zinc oxide (Zinc Hana 1, Nippon Chemical Industry) 5 parts by weight, magnesium oxide (Kyowa Mag 150, Kyowa Chemical Industry Co., Ltd.) 5 parts by weight, process oil (Diana PW) -150, Idemitsu Kosan) 10 parts by weight, sulfur (# 200, Tsurumi Chemical Industries) 1 part by weight, vulcanization accelerator (Noxeller TS, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part by weight, and vulcanization accelerator (Noxeller) (DT, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.5 parts by weight was kneaded, and then extrusion molding was performed so that the inner diameter became 70 mm with a thickness of 1.5 mm. Thereafter, the metal pipe having an outer diameter of 84 mm was expanded and coated (elongation rate 20 times), and steam vulcanized with a vulcanizer at 150 ° C. for 1 hour. Further, the belt after vulcanization was finished to a thickness of 450 μm by grinding the front and back sides with a cylindrical grinder.

(Preparation of protective layer)
On the surface of the obtained belt base material, a coating solution in which 5 parts by mass of carbon black is added to 100 parts by mass of JLY-601 ESD (manufactured by Japan Atchison) is spray-coated so as to have a thickness of 10 μm. A protective layer was formed by heating at 0 ° C. for 30 minutes.
The volume resistivity of the obtained semiconductive belt was 5 × 10 ⁸ Ωcm.

<Comparative example 2>
(Preparation of belt substrate)
75 parts by weight of polychloroprene rubber (ES-40, manufactured by Denki Kagaku Kogyo), 25 parts by weight of epichlorohydrin copolymer (Zeklon 3106, manufactured by Nippon Zeon), 20 parts by weight of carbon (Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.) Chain black EC (Asahi Carbon Co., Ltd.) 8 parts by weight, zinc oxide (Zinc Hana 1, Nippon Chemical Industry) 5 parts by weight, magnesium oxide (Kyowa Mag 150, Kyowa Chemical Industry Co., Ltd.) 5 parts by weight, process oil (Diana PW) -150, Idemitsu Kosan) 10 parts by weight, sulfur (# 200, Tsurumi Chemical Industries) 1 part by weight, vulcanization accelerator (Noxeller TS, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part by weight, and vulcanization accelerator (Noxeller) (DT, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.5 parts by weight was kneaded, and then extrusion molding was performed so that the inner diameter was 83 mm with a thickness of 1.0 mm. Thereafter, a metal pipe having an outer diameter of 84 mm was coated (elongation rate was 1%), and steam vulcanization was performed in a vulcanization can at 150 degrees for 1 hour. Further, the belt after vulcanization was finished to a thickness of 450 μm by grinding the front and back sides with a cylindrical grinder.

(Preparation of protective layer)
On the surface of the obtained belt base material, a coating solution in which 5 parts by mass of carbon black is added to 100 parts by mass of JLY-601 ESD (manufactured by Japan Atchison) is spray-coated so as to have a thickness of 10 μm. A protective layer was formed by heating at 0 ° C. for 30 minutes.
The volume resistivity of the obtained semiconductive belt was 5 × 10 ⁸ Ωcm.

<Evaluation>
The semiconductive belts of Example 5 and Comparative Example 2 were mounted on DocuCenter 507 manufactured by Fuji Xerox Co., Ltd. as a paper transport belt, and the transfer performance was evaluated by the following method. The configuration of the image forming apparatus is substantially the same as that of the image forming apparatus 400 shown in FIG.

<Image quality evaluation>
In the image quality evaluation, an initial image (halftone image) and an evaluation of a halftone image after running 10,000 images with an area coverage of 5% were performed using X-Rite 938 manufactured by X-Rite. The results are shown in Table 2.
The evaluation index of the image density change is as follows.
○: Initial image density and density difference after running 10,000 sheets are less than 0.2 points ×: Initial image density and density difference after running 10,000 sheets are 0.2 points or more

As apparent from Table 2, according to the image forming apparatus provided with the semiconductive belt of the present invention as the sheet conveying belt, the volume resistivity change amount is 0.8 (log Ωcm) or less, the initial image density and It can be seen that there is little difference from the image density after running 10,000 sheets, and the deterioration of transfer performance with time is suppressed.
On the other hand, in the image forming apparatus provided with the semiconductive belt of Comparative Example 2, it was found that the difference between the initial image density and the image density after running 10,000 sheets was greatly changed.
From the above, it has been found that the semiconductive belt of the present invention can stabilize the transfer performance by being used as an intermediate transfer belt or a paper transport belt.

It is a figure which shows the measuring method of volume resistivity, (a) is a top view, (b) is XX sectional drawing. It is a schematic sectional drawing which shows one Embodiment of the laminated constitution of the semiconductive belt of this invention. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention. It is a schematic block diagram which shows other one Embodiment of the image forming apparatus of this invention.

Explanation of symbols

1 Semiconductive belt (intermediate transfer belt)
1 'Semi-conductive belt (transfer conveyor belt)
6 Photosensitive drum (image carrier)
7, 7 'Recording material 8 Transfer device 8a Primary transfer device 8b Secondary transfer device 9 Stretching roll 10 Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 11 Charging device 12 Exposure measure 13 Rotary type developing device 13a, 13b, 13c, 13d Developing device 17 Cleaning device 20 Intermediate transfer belt 21, 22, 23, 24 Stretching roll 25 Primary transfer roll 27 Belt cleaning device 30 Secondary transfer roll 40 recording material 41 supply tray 42 feed roll 43 transport roll 44 resist roll 45 fixing device 46 fixing roll 47 pressure roll 101 belt base material 102 protective layer b semiconductive belt

Claims (2)

It has a base material that has been vulcanized in a state of containing an elastic body and stretched under the condition of an elongation ratio of 20% or more, and a protective layer provided on the base material, and has a volume resistivity when not stretched. Semiconductivity, characterized in that it is in the range of 10 ⁷ to 10 ¹¹ Ωcm, and the difference in common logarithm of volume resistivity between non-stretched and 5% stretched is 0.8 (log Ωcm) or less belt.   An image forming apparatus comprising the semiconductive belt according to claim 1 as an intermediate transfer belt or a sheet conveying belt.

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