JP5014540B2 - Semiconductive endless belt and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used to transfer a toner image formed on the surface of a photoreceptor to a recording medium such as paper in an electrostatic recording process in an electrophotographic apparatus such as a copying machine or a printer, or an electrostatic recording apparatus. The present invention relates to a semiconductive endless belt and an image forming apparatus comprising the semiconductive endless belt.
[0002]
[Prior art]
Conventionally, in electrostatic recording processes such as copying machines and printers, first, the surface of a photosensitive member (latent image holding member) is uniformly charged, and an image is projected onto the photosensitive member from an optical system so as to be exposed to light. An electrostatic latent image is formed by erasing the charged portion, and then a toner is supplied to the electrostatic latent image to form a toner image by electrostatic adhesion of the toner. A method of printing by transferring to a recording medium such as photographic paper is employed.
In this case, color printers and color copiers basically perform printing according to the above process. However, in the case of color printing, the color tone is adjusted using toners of four colors, magenta, yellow, cyan, and black. In order to reproduce the image, a process for obtaining a required color tone by superimposing these toners at a predetermined ratio is required, and several methods have been proposed for performing these processes.
First, as in the case of monochrome printing, when the electrostatic latent image is visualized by supplying toner onto the photoreceptor, the four-color toner images of magenta, yellow, cyan, and black are formed. There are multiple development methods. According to this method, it is possible to configure the apparatus relatively compactly, but there is a problem that gradation control is very difficult and high image quality cannot be obtained.
[0003]
Second, four photosensitive drums are provided, and the latent image on each drum is developed with magenta, yellow, cyan, and black toners, so that a magenta toner image, a yellow toner image, a cyan toner image, and a black toner image are obtained. A color image is formed by forming four toner images of the toner image, aligning the photosensitive drums on which these toner images are formed in a row, sequentially transferring each toner image onto a recording medium such as paper, and superimposing the toner image on the recording medium. There is a tandem method to reproduce. Although this method can obtain a good image, the four photosensitive drums and the charging mechanism and the developing mechanism provided for each photosensitive drum are arranged in a line, which increases the size of the apparatus and is expensive. Become.
FIG. 1 shows a configuration example of a printing unit of a tandem type image forming apparatus. A printing unit composed of the photosensitive drum 1, the charging roller 2, the developing roller 3, the developing blade 4, the toner supply roller 5, and the cleaning blade 6 corresponds to each toner of yellow Y, magenta M, cyan C, and black B 4 The toner images are sequentially transferred onto a sheet that is circulated by a driving roller (driving member) 9 and conveyed by a transfer conveying belt 10 to form a color image. Charging and discharging of the transfer / conveying belt 10 are performed by the charging roller 7 and the discharging roller 8, respectively. In addition, a suction roller (not shown) is used for charging the sheet for attracting the sheet to the belt. Owing to these measures, generation of ozone can be suppressed. The suction roller places the paper on the transfer conveyance belt 10 from the conveyance path and performs electrostatic adsorption on the transfer conveyance belt 10. Further, the sheet separation after the transfer can be performed only by the curvature separation by lowering the transfer potential to weaken the adsorption force between the sheet and the transfer conveyance belt 10.
[0004]
By the way, there are a resistor and a dielectric as the material of the transfer / conveying belt 10, and each has advantages and disadvantages. Since the resistance belt has a short charge holding time, when the tandem transfer is used, the charge injection in the transfer is small, and the voltage rise is relatively small even in continuous transfer of four colors. Even when it is repeatedly used for the transfer of the next sheet, the electric charge is released, so that no electrical reset is required. However, since the resistance value changes due to environmental fluctuations, there are disadvantages such as environmental fluctuations affecting transfer efficiency and being easily affected by the thickness and width of the paper.
On the other hand, in the case of a dielectric belt, since there is no spontaneous release of injected charge, it is necessary to electrically control both injection and release of charge. Reliable and highly accurate paper supply can be performed. In addition, since the dielectric constant is less dependent on temperature and humidity, the transfer process is relatively stable with respect to the environment. However, each time the transfer is repeated, charges are accumulated on the belt, so that there is a disadvantage that the transfer voltage becomes high.
[0005]
As a third method, a recording medium such as paper is wound around a transfer drum and rotated four times, and magenta, yellow, cyan, and black on the photosensitive member are sequentially transferred to the recording medium every turn so that a color image is obtained. There is a transfer drum system to reproduce. According to this method, a relatively high image quality can be obtained. However, when the recording medium is a cardboard such as a postcard, it is difficult to wind the recording medium around the transfer drum, and the type of the recording medium is limited. There is a point.
[0006]
In contrast to the multiple development system, tandem system, and transfer drum system, intermediate transfer is a system in which good image quality is obtained, the size of the apparatus is not increased, and the type of recording medium is not particularly limited. A scheme has been proposed.
In this intermediate transfer method, an intermediate transfer member composed of a drum or a belt is provided for temporarily transferring and holding the toner image on the photosensitive member, and a magenta toner image, a yellow toner image, and a cyan toner are provided around the transfer member. By arranging four photoconductors on which toner images and black toner images are formed and sequentially transferring the four color toner images onto the intermediate transfer member, a color image is formed on the intermediate transfer member. Is transferred onto a recording medium such as paper. Therefore, since the gradation is adjusted by superimposing the four color toner images, it is possible to obtain high image quality, and it is not necessary to arrange the photoconductors in a row as in the tandem method. The device does not increase in size. In addition, since there is no need to wrap the recording medium around the drum, the type of recording medium is not limited.
There is also a tandem intermediate transfer system that combines the tandem system and the intermediate transfer system.
[0007]
FIG. 2 is a diagram illustrating a configuration example of an image forming apparatus that uses an endless belt-like intermediate transfer member (endless belt) as the intermediate transfer member and forms a color image by an intermediate transfer method. In the figure, reference numeral 11 denotes a drum-shaped photoconductor, which rotates in the direction of the arrow in the figure. The photosensitive member 11 is charged by the primary charger 12, and then the charged portion of the exposed portion is erased by image exposure 13 to form an electrostatic latent image. Further, the electrostatic latent image is first developed by the developing device 41. By developing with the color magenta toner M, a magenta toner image of the first color is formed on the photoreceptor 11. Next, the toner image is circulated and driven by a driving roller 30 as a driving member, and is transferred to an intermediate transfer member 20 composed of an endless belt that rotates in contact with the photoreceptor 11. The transfer to the intermediate transfer member 20 is performed by a primary transfer bias applied to the intermediate transfer member 20 from the power source 61 at the nip portion between the photoreceptor 11 and the intermediate transfer member 20. After the first color magenta toner image is transferred to the intermediate transfer member 20, the surface of the photoconductor 11 is cleaned by the cleaning device 14, and the first development transfer operation of the photoconductor 11 is completed. Thereafter, the photoconductor 11 is rotated three times, and the developing devices 42, 43, and 44 are sequentially used for each rotation, and the second color cyan toner image, the third color yellow toner image, and the fourth color are obtained in the same manner as described above. Color black toner images are sequentially formed on the photoreceptor 11 and are superimposed and transferred to the intermediate transfer member 20 for each turn, so that a composite color toner image corresponding to the target image is formed on the intermediate transfer member 20. . In the image forming apparatus of FIG. 2, the developing devices 41 to 44 are sequentially replaced with each rotation of the photoreceptor 11 so that development with magenta toner M, cyan toner C, yellow toner Y, and black toner B is sequentially performed. It has become.
[0008]
Next, the transfer roller 25 contacts the intermediate transfer member 20 on which the composite color toner image is formed, and a recording medium 26 such as paper is fed from the paper feed cassette 19 to the nip portion. At the same time, a secondary transfer bias is applied from the power source 29 to the transfer roller 25, and the composite color toner image is transferred from the intermediate transfer member 20 onto the recording medium 26 and fixed by heating. After the composite color toner image is transferred to the recording medium 26, the residual toner on the surface of the intermediate transfer member 20 is removed by the cleaning device 35, and the intermediate transfer member 20 returns to the initial state to prepare for the next image formation. ing.
As such an endless belt-shaped intermediate transfer member (endless belt) 20, conventionally, a semiconductive resin film belt and a rubber belt having a fiber reinforcement are mainly used. Among these, as a semiconductive resin film belt, what added the electrically conductive agent to resin, such as a polycarbonate and a polyimide, is proposed conventionally.
[0009]
[Problems to be solved by the invention]
By the way, in the tandem type, intermediate transfer type and tandem intermediate transfer type image forming apparatuses using the conductive endless belt, any endless belt is required to have a semiconductive region resistance. In reality, it is difficult to control the resistance.
In general, as a method for controlling the resistance of the belt, a method of adding a conductive substance such as ion, carbon, metal oxide or the like to a layer made of resin or the like and controlling the addition amount is adopted. When using ions, there is little variation in resistance, but not only a relatively high resistance region can be covered, but the resistance is easily influenced by the environment, the resistance is easily changed by energization, and ions can bleed and become a source of contamination. I have problems such as being easy to become.
On the other hand, when a conductive material such as carbon or metal oxide is used, the resistance is less influenced by the environment, the resistance change due to energization is less, the contamination problem is less likely to occur, and the required resistance area can be covered. Although there are many advantages, there are problems such as large variation in resistance and large voltage dependency of resistance. Therefore, in order to improve the reproducibility and stability of resistance, some attempts have been made to add a dispersant together with the conductive material. However, the additive itself causes a new problem that it is likely to become a contamination source. Yes.
[0010]
The present invention has been made in view of the conventional problems, and is used in a tandem type, intermediate transfer type, and tandem intermediate transfer type image forming apparatus, and the like. An object is to provide an image forming apparatus equipped with a semiconductive endless belt.
[0011]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have used a conductive agent pre-coated with a resin having a high charge attenuation property as a conductive agent to be added to the resin layer constituting the belt, thereby reducing the resistance variation. The present inventors have found that an endless belt can be stably obtained, and have arrived at the present invention. The semiconductive endless belt of the present invention can be used as a transfer member for tandem, intermediate transfer, and tandem intermediate transfer image forming apparatuses.
That is, the invention described in claim 1 is a semiconductive endless belt for an image forming apparatus that is circulated and driven by a driving member and transfers a toner image to a recording medium. The above corona when the resin is charged by generating a corona discharge by applying a voltage of 8 kV to a subject roller coated with a resin having a thickness of 5 μm on the outer periphery of the roller and a corona discharger disposed at a distance of 1 mm. The maximum value of the surface potential 0.3 seconds after the occurrence of discharge is 300 V or less in absolute value, and the charge attenuation is high Acrylic urethane resin or urethane resin The conductive agent previously coated with is added.
According to a second aspect of the present invention, there is provided a toner formed on the surface of each image forming body by conveying a recording medium that is circulated and driven by a driving member and held by electrostatic adsorption to four types of image forming bodies. On the recording medium Sequentially A semi-conductive endless belt used for transfer / conveyance of a tandem transfer system for transferring, a test roller in which a resin layer constituting the belt is coated with a resin having a thickness of 5 μm on the outer periphery of a metal roller; When a voltage of 8 kV is applied to a corona discharger arranged with a 1 mm interval to generate a corona discharge and the resin is charged, the maximum value of the surface potential after 0.3 seconds from the occurrence of the corona discharge is High charge attenuation with absolute value of 300V or less Acrylic urethane resin or urethane resin The conductive agent previously coated with is added.
According to a third aspect of the present invention, the toner image formed on the surface of the image forming body, which is circulated and driven by the driving member and disposed between the image forming body and the recording medium, is temporarily placed on the surface of the image forming body. A semiconductive endless belt for an intermediate transfer member for transferring and holding and transferring this to a recording medium, wherein the resin layer constituting the belt is coated with a resin having a thickness of 5 μm on the outer periphery of a metal roller. Surface potential 0.3 seconds after generation of corona discharge when a voltage of 8 kV is applied to a corona discharger disposed with a distance of 1 mm from the subject roller to generate corona discharge and charge the resin. Charge attenuation is high, the maximum value of which is 300V or less in absolute value Acrylic urethane resin or urethane resin The conductive agent previously coated with is added.
The semiconductive endless belt is generally classified into one having a joint and one having no joint (a so-called seamless belt), but any one may be used in the present invention.
[0012]
In the semiconductive endless belt according to claim 4, the amount of the resin to be coated is 0.01 to 50 wt% with respect to the conductive agent.
In the semiconductive endless belt according to claim 5, the conductive agent is at least one of carbon, metal powder, metal oxide, or a mixture thereof.
The semiconductive endless belt according to claim 6, Acrylic urethane Conductive agent coated with resin And Solvent used when measuring the solvent insolubility (%) of the resin shown in the following relational expression But With methyl ethyl ketone or toluene Yes, the above Acrylic urethane The solvent insolubility rate of the resin is 50% or more.
Solvent insolubility (%) = (B / A) × 100
However, A: Weight before immersion of the resin component in the resin-coated conductive agent
B: Resin-coated conductive agent in solvent at 25 ° C. for 24 hours
Weight of resin component after immersion
The semiconductive endless belt according to claim 7 has a belt surface roughness of 6 μm or less.
An image forming apparatus according to an eighth aspect is characterized in that the semiconductive endless belt according to any one of the first to seventh aspects is mounted.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The semiconductive endless belt of the present invention is driven by a driving member such as the driving roller 9 shown in FIG. 1, for example, and transfers a toner onto a recording medium conveyed along with the driving member. 2 is disposed between the photosensitive member 11 and the recording medium 26 such as paper as shown in FIG. 2 and is circulated and driven by a driving member such as a driving roller 30 so that the photosensitive member 11 is The toner image formed on the surface is temporarily transferred to the recording medium 26 and then used for an intermediate transfer member 20 used in an intermediate transfer type image forming apparatus.
[0014]
In the present invention, when a conductive agent is added to the resin forming the resin layer of these semiconductive endless belts, a conductive agent that has been previously coated with a resin is used as the conductive agent. Compared to the case where a conductive agent such as normal carbon or metal oxide, which is an uncoated conductive agent, is added as it is, it becomes easier to control the dispersibility of the conductive agent, resulting in resistance variation and resistance voltage. The dependency can be reduced.
At this time, the coating amount of the resin is suitably 0.01 to 50 wt%, preferably 0.01 to 30 wt%, more preferably 0.01 to 20 wt% with respect to the original conductive agent to be coated. is there. If the coating amount is less than the above range, a sufficient effect of improving dispersibility cannot be obtained, and if it is more than the above range, sufficient conductivity cannot be obtained as will be described later.
By the way, when the resin is simply coated, naturally, the original conductivity of the conductive agent is impaired, and the dispersibility can be controlled, but the conductivity is hardly exhibited. Therefore, in the present invention, by selecting a resin having a high charge attenuating property (a fast charge attenuating property) as a resin to be coated on the conductive agent, the trade-off between dispersibility and conductivity is contradictory. Solve a problem.
[0015]
The charge attenuating property is obtained by applying a voltage of 8 kV to a corona discharger disposed at a distance of 1 mm from the film surface by forming a resin to be coated into a film having a thickness of 3 to 10 μm. It is obtained by charging the resin surface and measuring the change in surface potential. In this case, as the resin to be coated, it is important to select a resin whose maximum value of the surface potential after 0.3 seconds is 300 V or less, preferably 200 V or less.
The surface potential is measured by, for example, Charge Roller Test System CRT2000 of QEA (Quality Engineering Associates, Inc.). FIG. 3 shows a schematic diagram of the main part. That is, measurement is performed by holding both ends of a shaft 72 of a metal object roller 71 having a coating resin disposed on the surface with a chuck 73, and a small scorotron discharger 81 and a surface potential meter 82 separated at a predetermined interval. The unit 80 is disposed opposite to the surface of the subject roller 71 with an interval of 1 mm, and the measurement unit 80 is moved from one end of the subject roller 71 to the other end while the subject roller 71 is stationary. A method of measuring the surface potential while giving a surface charge to the subject roller 71 by moving at a constant speed is suitably employed.
Since the surface potential depends on temperature and humidity, it is carried out in an atmosphere of normal temperature and normal humidity (20 ° C./50% RH) as a standard condition. The corona charge applied from the scorotron discharger 81 to the subject roller 71 is a negative charge, and the applied voltage is 8 kV. The speed of the measurement unit 80 is adjusted so as to measure the surface potential 0.3 seconds after the corona discharge is applied to the subject roller 71.
[0016]
The resin to be coated may be any resin type as long as the above-described charge attenuation condition is satisfied. Examples of the resin to be coated include urethane resin, acrylic resin, polyester resin, urethane-modified acrylic resin, silicone resin, nylon resin, epoxy resin, styrene resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, and fluorine resin. Etc. These resins may be used alone or in combination of two or more. Particularly, urethane resin, fluororesin, silicone resin, and acrylic urethane resin are suitable, and further, a belt described later is constituted. It is preferable that at least one kind of resin that is the same type as the resin used for the resin layer is included.
[0017]
The conductive agent to be coated is a so-called conductive substance, and examples thereof include carbon, metal, and metal oxide. For example, conductive carbon such as ketjen black, acetylene black, rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT, carbon for ink subjected to oxidation treatment, pyrolytic carbon, natural Examples thereof include graphite or metals such as antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium, or metal oxides.
[0018]
In addition, examples of the method for coating the resin include dispa coat and coatmizer.
Dispacoat is equipped with a powder supply unit provided at the top and a multistage disperser that can supply liquid in multiple stages from the lateral direction. The operating conditions of the multistage disperser are controlled to supply the powder. The operation of adhering the liquid component containing the coating resin to the surface of the conductive powder supplied from the section or wetting the surface of the conductive powder with the liquid can be performed in a very short time.
The coatmizer supplies the conductive powder to be coated in the jet jet to create a dispersed layer, and then forms a mist-like flow made up of droplets of droplets containing the coating resin in parallel to this. The surface of the conductive powder is then resin-coated by colliding with the coated conductive powder.
[0019]
Moreover, regarding the conductive agent coated with the resin, it is preferable that the solvent insolubility of the resin component shown in the following relational expression is 50% or more, particularly 70% or more.
Solvent insolubility (%) = (B / A) × 100
However, A: Weight before immersion of the resin component in the resin-coated conductive agent
B: Resin-coated conductive agent Melt In the medium, 25 ° C., 24 hours
Weight of resin component after immersion
When the solvent insolubility is less than 50%, when the semiconductive endless belt is mounted on an electrophotographic apparatus such as a printer, a copying machine, or a FAX, contamination occurs on a photosensitive member contact area such as OPC, Cause problems.
As the solvent for measuring the solvent insolubility, methyl ethyl ketone or the like is used for fluororesins, methanol is used for polyamide resins, methyl ethyl ketone or toluene is used for acrylic urethane resins, and melamine resin is used. Acetone, Isopropanol In addition, it is preferable to use toluene or the like for the silicone resin.
[0020]
The resin layer to which the conductive agent previously coated with the resin is added may be any material. For example, polyamide, polyimide, polycarbonate, polyarylate, polyacetal, polypropylene, polyethylene, polyphenylene ether, polysulfone, polyethylene Terephthalate, polybutylene terephthalate, polyethersulfone, polyetherimide, polybutadiene, polyisobutylene, polyvinyl fluoride, polyvinylidene fluoride, acrylic, alkyl acrylate ester copolymer, ethylene tetrafluoroethylene copolymer, hexafluoropropylene, par A kind of fluoroalkyl vinyl ether copolymer, polyester ester copolymer, polyester ether copolymer, polyurethane copolymer. Can also be a combination of two or more, in particular, polyamides, polycarbonates, acrylonitrile copolymers, polyvinylidene fluoride is preferred.
In addition, in addition to the above-described components, for example, various fillers, coupling agents, antioxidants, lubricants, surface treatment agents, pigments, and UV absorbers as long as the effects of the present invention are not impaired. Functional components such as a foaming agent, a crosslinking agent, and a compatibilizing agent may be appropriately blended.
Further, the resistance of the resin layer is appropriately selected, but 10 ⁶ -10 ¹³ Ω · cm, especially 10 ⁷ -10 ¹² It is preferable to adjust to a semiconductive region of Ω · cm. In the semiconductive region where the resistance variation is likely to occur, the resistance variation can be effectively reduced by adding the conductive agent previously coated with the resin of the present invention.
Further, the resin layer may be a single layer or a plurality of layers, and the thickness is appropriately selected. Usually, a range of 50 to 500 μm is used.
[0021]
Further, the semiconductive endless belt of the present invention has a driving roller 9 in the image forming apparatus in FIG. 1 or a driving roller 30 in FIG. 2, as shown in a sectional view in the belt width direction shown in FIG. A fitting part (broken line in the figure) that fits with the fitting part formed on the driving member may be formed on the surface that contacts the driving part, such as the semiconductive endless belt of the present invention. By providing such a fitting part and fitting it to a fitting part (not shown) provided on the drive member for running, it is possible to prevent the semiconductive endless belt from shifting in the width direction.
In this case, the fitting portion is not particularly limited, but as shown in FIG. 4A, the fitting portion has a continuous convex shape along the belt circumferential direction (rotating direction), and this is a driving roller or the like. It is preferable to fit in a groove formed along the circumferential direction of the drive member.
In addition, although the example which provided one continuous convex shape as a fitting part was shown in Fig.4 (a), this fitting part has many convex parts in a line along the belt circumferential direction (rotation direction). Further, as shown in FIG. 4B, two or more fitting portions may be provided, or may be provided at the center portion in the width direction of the belt. Further, the fitting portion is not a convex shape as shown in FIGS. 4 (a) and 4 (b), but is a groove along the belt circumferential direction (rotation direction), and this is the drive roller 9 (or drive). You may make it fit with the convex part formed along the circumferential direction of drive members, such as roller 30).
[0022]
Further, the surface roughness of the semiconductive endless belt of the present invention is not particularly limited, but the surface roughness is preferably 6 μm or less, more preferably 3 μm or less in terms of JIS ten-point average roughness Rz. .
Examples of the image forming apparatus using the semiconductive endless belt of the present invention include the tandem system shown in FIG. 1, the intermediate transfer system shown in FIG. 2, or the tandem intermediate transfer system. However, it is not limited to these.
In the case of the apparatus of FIG. 2, a voltage can be applied from an appropriate power source 61 to the driving roller 30 (or driving gear) that rotates the intermediate transfer member 20 of the present invention. Application conditions can be selected as appropriate, such as application of only AC or application of superimposing alternating current on direct current.
Further, the method for producing the semiconductive endless belt of the present invention is not particularly limited. For example, a conductive agent previously coated with a resin is kneaded with a biaxial kneader, and the obtained kneaded product is formed into an annular die. And can be manufactured by extrusion. Alternatively, a powder coating method such as electrostatic coating can be appropriately employed.
[0023]
<Example>
Examples The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following.
[Example 1]
100 parts by weight of acrylonitrile / butadiene / styrene resin (manufactured by Daicel Polymer: Sebian V680) and the following resin coating CB type A are melt-kneaded by a biaxial kneader, and the resulting kneaded product is extruded and molded. A semiconductive endless belt having dimensions of 245 mm, a thickness of 100 μm and a width of 250 mm was obtained.
As the resin coating CB type A, ketjen black carbon (manufactured by Lion) was used, and acrylic urethane resin EAU65B (manufactured by Asia) / IPDI crosslinking agent Excel Hardener HX (manufactured by Asia) was selected as the resin to be coated in advance. In addition, the ratio of EAU65B and Excel hardener HX was adjusted and used so that it might become 6: 4 by solid content weight ratio.
The coating method is to use a spiral flow device (Freund) with a ketjen black carbon in a fluidized state and spray the MEK solvent with a mixture of the acrylic urethane resin and the cross-linking agent in the form of a mist. The surface of the chain black carbon was coated with the above resin and heated to prepare ketjen black carbon particles coated with the resin in advance.
[0024]
[Example 2]
In Example 1, the resin to be coated beforehand is urethane resin DP307 (manufactured by Sanyo Chemical Co., Ltd.) / IPDI crosslinking agent Excel Hardener HX (manufactured by Asia Industries), except that resin coating CB type B is used. Similarly, a semiconductive endless belt was produced.
The ratio of DP307 to Excel Hardener HX was adjusted so that the solid content weight ratio was 4.5 to 1.
[Example 3]
In Example 1, except that the resin constituting the belt was changed from acrylonitrile / butadiene / styrene resin (Cebian V680) to polybutylene terephthalate resin (manufactured by Daicel Polymer: Novalloy B1700), the same as in Example 1 above, A semiconductive endless belt was prepared.
[0025]
[Reference Example 1]
A semiconductive endless belt was produced in the same manner as in Example 1 except that the resin coating CB Type C was used in which the coating spray conditions were adjusted and the amount of the coating resin was increased.
[Reference Example 2]
Instead of the resin coating CB type A used in Example 1 above, a resin coating CB type D in which the resin to be pre-coated in the resin coating CB type A is only acrylic urethane resin EAU65B (manufactured by Asia) is used. Except for the above, a semiconductive endless belt was produced in the same manner as in Example 1 above.
[0026]
[Comparative Example 1]
Instead of the resin coating CB type A used in Example 1 above, the resin to be coated in advance in the resin coating CB type A was epoxy resin AER6071 (manufactured by Asahi Kasei) / curing agent Sumicure M (manufactured by Sumitomo Chemical). A semiconductive endless belt was produced in the same manner as in Example 1 except that CB type E was used. Note that the ratio of AER6071 to SumiCure M was adjusted to 7: 2.
[Comparative Example 2]
In Example 1, the ketjen black carbon was used as it was without being coated with a resin, and a semiconductive endless belt was produced in the same manner as in Example 1 except that.
[0027]
The results of evaluating the respective characteristics of the semiconductive endless belts of Examples, Reference Examples and Comparative Examples thus prepared according to the following criteria are shown in the table of FIG.
In addition, about the measurement of a characteristic and the test result, it performed according to the following references | standards.
(1) Charging potential of pre-coated resin
A sample roller was prepared by coating the outer periphery of a metal roller having the same diameter as the charging roller with only the resin to be coated to a thickness of 5 μm. Using a CRT2000 device manufactured by QEA, this subject roller is applied with a voltage of 8 kV to a scorotron discharger disposed at a distance of 1 mm from the subject roller to generate a corona discharge to charge the subject roller surface, The surface potential after 0.3 seconds was measured. The measurement was carried out in an atmosphere of normal temperature and normal humidity (20 ° C./50% RH).
(2) Amount of coated resin
For carbon previously coated with resin, a temperature rising rate of 20 ° C./min. The temperature was raised to 800 ° C. and the amount of coated resin was calculated from the change in weight.
(3) Solvent insolubility
The carbon coated in advance with resin was immersed in an MEK solution at 25 ° C. for 24 hours and then dried at 100 ° C. for 5 hours, and the weight after drying was measured. The solvent insolubility rate was calculated according to the following formula from the amount of resin before immersion from the TGA and the change in weight before and after immersion.
Solvent insolubility (%) = (B / A) × 100
Here, A represents the weight of the resin component in the resin-coated conductive agent before immersion in the solvent, and B represents the weight of the resin component after immersion of the conductive agent coated in the good solvent at 25 ° C. for 24 hours.
(4) Belt surface roughness
The surface of the produced semiconductive endless belt was measured for 10-point average roughness Rz using a surface roughness measuring device (Tokyo Seimitsu: Surfcom 120A).
(5) Belt volume resistivity and resistance variation
About the produced semiconductive endless belt, the volume resistivity was measured with the applied voltage 250V using the resistance meter (Mitsubishi Oil Chemical Electronics company make: Hiresta).
In addition, while the produced semiconductive endless belt and the metal drum are pressed against each other with a load of 500 g and rotated, 250 V is applied between the semiconductive endless belt and the metal drum, and the semiconductive endless belt makes one round. The difference between the maximum resistance and the minimum resistance was defined as the resistance variation.
(6) Image output and contamination test
The produced semiconductive endless belt and the OPC drum were pressed against each other with a load of 1000 kg and left in an environment of 40 ° C. and 85% RH for 20 days. Then, the OPC drum was mounted on the printer device, and 10 images were printed. The contamination state was determined based on the degree of image failure during the printing of these 10 sheets. At this time, a case where a line-like defect occurred at the image position corresponding to the pressure contact portion was determined as NG.
[0028]
As is clear from the characteristic measurement results and test results shown in FIG. 5, the semiconductive endless belts of Examples 1 to 3 of the present invention have a small resistance variation and a stable resistance. When mounted, a good image could be obtained and no contamination problem occurred.
On the other hand, in Reference Example 1 in which the coating amount of Example 1 was increased, although the variation in resistance was small, the resistance increased significantly and the surface roughness deteriorated, and the image also had a slightly sandy pattern. It was. On the other hand, in Reference Example 2 in which the cross-linking agent of Example 1 was omitted, the resistance and the variation in resistance were the same as in Example 1, but a contamination problem occurred.
Further, in Comparative Example 1 in which a resin having a slow charge decay was used as the coating resin, the resistance variation was large and the charging potential was greatly increased. In addition, a sandy pattern was seen in the image, and a line-like defect occurred, resulting in NG.
Further, in Comparative Example 2 in which carbon was used as it was without being coated with resin, although the resistance value could be adjusted, the dispersibility was poor, the resistance variation was large, and a sand pattern was seen in the image.
[0029]
【Effect of the invention】
As described above, according to the present invention, when a semiconductive endless belt is manufactured, a conductive agent coated with a resin having a high charge attenuation property is used as the conductive agent added to the resin layer constituting the belt. As a result, a semiconductive endless belt having a small resistance variation and a stable resistance can be obtained.
Also, an image forming apparatus capable of stably obtaining a good image by mounting the semiconductive endless belt on an image forming apparatus of a tandem system, an intermediate transfer system, or a tandem intermediate transfer system is provided. Can do.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a printing unit of an image forming apparatus using a tandem method.
FIG. 2 is a diagram illustrating a configuration example of an image forming apparatus using an intermediate transfer method.
FIG. 3 is a diagram showing a method for measuring a surface potential.
FIG. 4 is a cross-sectional view in the width direction of a semiconductive endless belt.
FIG. 5 is a diagram showing a trial result of a semiconductive endless belt according to the present invention.
[Explanation of symbols]
1 photosensitive drum, 2 charging roller, 3 developing roller, 4 developing blade,
5 toner supply roller, 6 cleaning blade,
7 Transfer roller belt charging roller, 8 Static elimination roller, 9 Drive roller,
10 Transfer conveyor belt, 11 Photoconductor, 12 Primary charger, 13 Image exposure,
14 cleaning device, 19 paper feed cassette, 20 intermediate transfer member,
25 transfer roller, 26 recording medium, 29 power supply for secondary transfer bias,
30 driving roller, 35 intermediate transfer member cleaning device,
41 to 44 developing device, 61 power supply for primary transfer bias, 71 sample roller,
72 shaft, 73 chuck, 80 measuring unit,
81 scorotron discharger, 82 surface potential meter.

Claims (8)

In a semiconductive endless belt for an image forming apparatus that is circulated by a driving member and transfers a toner image to a recording medium,
In the resin layer constituting the belt,
When charging the resin by generating a corona discharge by applying a voltage of 8 kV to a subject roller coated with a resin of thickness 5 μm on the outer periphery of a metal roller and a corona discharger disposed at a distance of 1 mm A conductive agent pre-coated with an acrylic urethane resin or urethane resin having a high charge attenuating property and having a maximum surface potential of 300 V or less in absolute value 0.3 seconds after the occurrence of corona discharge is added. Semi-conductive endless belt. Tandem transfer in which a recording medium that is circulated by a driving member and held by electrostatic attraction is conveyed to four types of image forming bodies, and toner images formed on the surfaces of the image forming bodies are sequentially transferred to the recording medium. A semi-conductive endless belt used for transfer / conveyance of the system,
In the resin layer constituting the belt,
When charging the resin by generating a corona discharge by applying a voltage of 8 kV to a subject roller coated with a resin of thickness 5 μm on the outer periphery of a metal roller and a corona discharger disposed at a distance of 1 mm A conductive agent pre-coated with an acrylic urethane resin or urethane resin having a high charge attenuating property and having a maximum surface potential of 300 V or less in absolute value 0.3 seconds after the occurrence of corona discharge is added. Semi-conductive endless belt. Circulatingly driven by a drive member, disposed between the image forming body and the recording medium, the toner image formed on the surface of the image forming body is once transferred and held on the surface of the image forming body, and transferred to the recording medium. A semiconductive endless belt for an intermediate transfer member,
In the resin layer constituting the belt,
When charging the resin by generating a corona discharge by applying a voltage of 8 kV to a subject roller coated with a resin of thickness 5 μm on the outer periphery of a metal roller and a corona discharger disposed at a distance of 1 mm A conductive agent pre-coated with an acrylic urethane resin or urethane resin having a high charge attenuating property and having a maximum surface potential of 300 V or less in absolute value 0.3 seconds after the occurrence of corona discharge is added. Semi-conductive endless belt.   The semiconductive endless belt according to any one of claims 1 to 3, wherein an amount of the resin to be coated is 0.01 to 50 wt% with respect to the conductive agent.   The semiconductive endless belt according to any one of claims 1 to 4, wherein the conductive agent is at least one of carbon, metal powder, metal oxide, or a mixture thereof. The Te acrylic urethane resin coated conductive agent odor, a solvent is methyl ethyl ketone or toluene, which is used to measure the solvent insoluble rate of the resin shown in relationship: a (%), the solvent insoluble rate of the acrylic urethane resin The semiconductive endless belt according to any one of claims 1 to 5, characterized in that is 50% or more.
Solvent insolubility (%) = (B / A) × 100
However, A: Weight before immersion of the resin component in the resin-coated conductive agent B: Resin-coated conductive agent in a solvent at 25 ° C. for 24 hours
Weight of resin component after immersion   The semiconductive endless belt according to any one of claims 1 to 6, wherein the belt surface roughness is 6 µm or less.   An image forming apparatus comprising the semiconductive endless belt according to any one of claims 1 to 7.

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