JP2006235546A - Conductive endless belt and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive endless belt that can keep high transfer efficiency, prevent diffusion of toner and prevent decrease in picture quality, as well as hold destaticizing performance and prevent an image defect or the like caused by residual charges, and thereby, that can produce uniform electrification even during continuous printing or partial image printing, and assure a high quality image, and to provide an image forming apparatus using the belt. <P>SOLUTION: The conductive belt is provided to be used in various kinds of image forming apparatuses of a tandem system, an intermediate transfer system and a tandem intermediate transfer system. When the belt surface is charged at 8 kV application voltage using a corona discharger disposed at 1 mm distance from the belt surface, the maximum surface potential C1 on the top surface and C2 on the back surface at the time one second after charging satisfy the relation of C1>C2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive endless belt (hereinafter also simply referred to as a “belt”) and an image forming apparatus using the same, and more particularly, to electrostatic recording in an electrophotographic apparatus such as a copying machine or a printer, an electrostatic recording apparatus, or the like. In the process, a conductive material used for transferring a toner image formed by supplying a developer to the surface of an image forming body such as a latent image holding body holding an electrostatic latent image on the surface onto a recording medium such as paper. The present invention relates to a conductive endless belt and an image forming apparatus using the same.

  Conventionally, in an electrostatic recording process in a copying machine, a printer, etc., 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 and exposed to light. An electrostatic latent image is formed by erasing the charged portion, and then toner is supplied to the electrostatic latent image to form a toner image by electrostatic adhesion of the toner, which is formed on paper, OHP, photographic paper For example, a method of printing by transferring to a recording medium such as the above is employed.

  In this case, color printers and color copiers basically print according to the above process, but in the case of color printing, the color tone is reproduced using toners of four colors, magenta, yellow, cyan, and black. Therefore, a process for obtaining a necessary color tone by superimposing these toners at a predetermined ratio is required, and several methods have been proposed for performing this process.

  First, as in the case of monochrome printing, when the electrostatic latent image is visualized by supplying toner onto the photosensitive member, the four colors of magenta, yellow, cyan, and black are sequentially added. There is a multi-development system in which development is performed by superimposing and a color toner image is formed on the photoreceptor. According to this method, it is possible to configure the apparatus relatively compactly, but this method has a problem in that it is very difficult to control gradation and high image quality cannot be obtained.

  Second, four photosensitive drums are provided, and the latent images on each drum are developed with magenta, yellow, cyan, and black toners, respectively, so that a magenta toner image, a yellow toner image, a cyan toner image, and a black toner image are obtained. By forming four toner images of the toner image, arranging the photosensitive drums on which these toner images are formed in a line, sequentially transferring the toner images onto a recording medium such as paper, and superimposing them on the recording medium, a color image is formed. There is a tandem method to reproduce. Although this method can obtain a good image, the four photosensitive drums, the charging mechanism and the developing mechanism provided for each photosensitive drum are arranged in a line, and the apparatus becomes large and expensive. It becomes.

  FIG. 2 shows a configuration example of a printing unit of a tandem image forming apparatus. A printing unit composed of the photosensitive drum 1, the charging roll 2, the developing roll 3, the developing blade 4, the toner supply roll 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 are performed by the charging roll 7 and the discharging roll 8, respectively. Further, a suction roller (not shown) is used for charging the paper for sucking the paper onto the belt. Owing to these measures, generation of ozone can be suppressed. The suction roller places the paper on the transfer conveyance belt from the conveyance path and performs electrostatic adsorption on the transfer conveyance belt. Further, the sheet separation after the transfer can be performed only by the curvature separation by lowering the transfer voltage to weaken the adsorption force between the sheet and the transfer conveyance belt.

  As materials for the transfer / conveyance belt 10, there are a resistor and a dielectric, each having advantages and disadvantages. Since the resistor belt can hold charges for a short time, when it is used for tandem transfer, there is little charge injection during transfer, and the voltage rise is relatively small even during continuous transfer of four colors. In addition, when it is repeatedly used for the transfer of the next sheet, the electric charge is released, and no electrical reset is required. However, since the resistance value changes due to environmental fluctuations, there are disadvantages such as affecting transfer efficiency and being easily influenced by the thickness and width of the paper.

  On the other hand, in the case of a dielectric belt, there is no spontaneous release of injected charge, and both charge injection and discharge must be electrically controlled. However, since the charge is stably held, the sheet can be adsorbed reliably and can be conveyed with high accuracy. Since the dielectric constant is less dependent on temperature and humidity, the transfer process is relatively stable to the environment. The drawback is that the transfer voltage increases because charges are accumulated on the belt each time the transfer is repeated.

  Thirdly, a recording medium such as paper is wound around a transfer drum, and this is rotated four times, and magenta, yellow, cyan, and black on the photosensitive member are sequentially transferred to the recording medium every rotation to reproduce a color image. There is also a method. 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 system in which good image quality is obtained with respect to the multiple development system, tandem system and transfer drum system, the apparatus is not particularly large, and the type of recording medium is not particularly limited. As an example, an intermediate transfer method has been proposed.

  That is, in this intermediate transfer system, an intermediate transfer member composed of a drum or a belt for temporarily transferring and holding the toner image on the photosensitive member is provided, and a magenta toner image, a yellow toner image, and a cyan toner are provided around the intermediate transfer member. An image and four photoconductors on which a black toner image is formed are arranged, and four color toner images are sequentially transferred onto the intermediate transfer member, thereby forming a color image on the intermediate transfer member. The image 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, so that the apparatus can be used. There is no particular increase in size, and there is no need to wrap the recording medium around the drum, so the type of recording medium is not limited.

  As an apparatus for forming a color image by the intermediate transfer method, an image forming apparatus using an endless belt-shaped intermediate transfer member as an intermediate transfer member is illustrated in FIG.

  In FIG. 3, 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, and an electrostatic latent image corresponding to the first color component is formed on the photosensitive member 11. The electrostatic latent image is developed with the first color magenta toner M by the developing device 41, and a first color magenta toner image is formed on the photoreceptor 11. Next, the toner image is circulated by a driving roller (driving member) 30 and transferred to the intermediate transfer member 20 that rotates while rotating in contact with the photoreceptor 11. In this case, transfer from the photoconductor 11 to the intermediate transfer member 20 is performed by a primary transfer bias applied from the power source 28 to the intermediate transfer member 20 at the nip portion between the photoconductor 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 development transfer operation for the first rotation of the photoconductor 11 is completed. Thereafter, the photoconductor rotates three times, and the second color cyan toner image, the third color yellow toner image, and the fourth color black toner image are sequentially used by the developing units 42 to 44 for each turn. The toner image is formed on the intermediate transfer member 20 and is superimposed and transferred to the intermediate transfer member 20 every round, so that a composite color toner image corresponding to the target color image is formed on the intermediate transfer member 20. In the apparatus of FIG. 3, 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.

  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 heated and fixed to form a final image. After the composite color toner image is transferred to the recording medium 26, the transfer residual toner on the surface 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.

  There is also a tandem intermediate transfer method that combines a tandem method and an intermediate transfer method. FIG. 4 illustrates an image forming apparatus of a tandem intermediate transfer system that forms a color image using an endless belt-like tandem intermediate transfer member.

  In the illustrated apparatus, the first developing unit 54 a to the fourth developing unit 54 d that develop the electrostatic latent images on the photoconductive drums 52 a to 52 d with yellow, magenta, cyan, and black, respectively, along the tandem intermediate transfer member 50. The four-color toner images formed on the photosensitive drums 52a to 52d of the developing units 54a to 54d are sequentially driven by circulating the tandem intermediate transfer member 50 in the direction of the arrow in the drawing. By transferring, a color toner image is formed on the tandem intermediate transfer member 50, and the toner image is transferred onto a recording medium 53 such as paper to perform printout.

  In the figure, reference numeral 55 denotes a driving roller or tension roller for circulatingly driving the tandem intermediate transfer member 50, reference numeral 56 denotes a recording medium feeding roller, reference numeral 57 denotes a recording medium feeding device, and reference numeral 58 denotes a recording medium. 3 shows a fixing device for fixing the image by heating or the like. Reference numeral 59 denotes a power supply device (voltage applying means) for applying a voltage to the tandem intermediate transfer member 50. The power supply device 59 transfers the toner image from the photosensitive drums 52a to 52d to the tandem intermediate transfer member 50. In this case, the polarity of the applied voltage can be reversed between the case where the image is transferred from the tandem intermediate transfer member 50 onto the recording medium 53.

  As the conductive endless belt used as the transfer conveyance belt 10, the intermediate transfer member 20, the tandem intermediate transfer member 50, etc. in the various image forming apparatuses described above, conventionally, a semiconductive resin film belt and a fiber reinforcement have been provided. Rubber belts are mainly used, and recently, many resin film belts with various improvements have been proposed because of their advantages such as low cost.

  By the way, in order to obtain a good image in image formation using such a conductive endless belt, it is important that the belt surface can uniformly hold an appropriate amount of charge during image formation. However, if the charge holding capability on the belt surface is too low, transfer efficiency is lowered, causing toner diffusion and image quality degradation. On the other hand, if the charge retention capability of the entire belt is too high, the charge is not sufficiently released at the end of image formation, and image defects such as spots caused by residual charges, density unevenness, and white image fogging occur. Problems such as image defects will occur. That is, regarding the charge holding ability of the belt, these conflicting demands exist, and it is necessary to design the belt based on a balance between the two.

As an improved technique related to the belt, for example, Patent Document 1 describes a semiconductive endless belt in which a conductive agent in which a resin having a high charge attenuation property is previously coated is added to a resin layer constituting the belt. Further, in Patent Document 2, in an endless belt formed by a centrifugal molding method having two layers of a front surface layer and a back surface layer composed of a thermosetting polyimide resin layer, the two layers are simultaneously ring-closed imidized. In addition, there is described an endless belt in which the relationship between the surface electrical resistance value of both layers and the volume resistance value of the endless belt is respectively prescribed.
JP2003-911165A (Claims etc.) JP 2004-29769 A (Claims etc.)

  As described above, various technologies have been proposed for the conductive endless belt. However, the above conflicting demands regarding the charge retention capability can be satisfied, and high efficiency can be achieved without causing problems such as a decrease in transfer efficiency and image defects. A new technique that enables the formation of quality images has been desired.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to ensure high transfer efficiency, prevent toner diffusion, and prevent deterioration of image quality in resin film belts used in various image forming apparatuses of tandem, intermediate transfer, and tandem intermediate transfer systems. In addition, it can guarantee static elimination performance and prevent problems such as the occurrence of image defects due to residual charge, and uniform charging can be obtained even during continuous printing or partial image printing. Another object of the present invention is to provide a high-performance conductive endless belt capable of reliably obtaining a high-quality image and an image forming apparatus using the same.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by defining the relationship between the charge holding ability between the front side and the back side of the conductive endless belt surface using predetermined parameters. The present invention has been completed.

In other words, the conductive endless belt of the present invention is configured to circulate and drive a recording medium held by electrostatic adsorption to four types of image forming bodies by a driving member, and sequentially transfer each toner image to the recording medium. For conductive endless belts for tandem transfer and transport,
The maximum value of the surface potential after 1 second when the surface was charged with an applied voltage of 8 kV using a corona discharge device arranged at a distance of 1 mm from the belt surface was C1 on the front side and C2 on the back side. In this case, the relationship of C1> C2 is satisfied.

Further, another conductive endless belt of the present invention is disposed between the image forming body and the recording medium, and is circulated and driven by a driving member to temporarily transfer the toner image formed on the surface of the image forming body. In the conductive endless belt for the intermediate transfer member that is transferred and held on the surface and transferred to the recording medium,
The maximum value of the surface potential after 1 second when the surface was charged with an applied voltage of 8 kV using a corona discharge device arranged at a distance of 1 mm from the belt surface was C1 on the front side and C2 on the back side. In this case, the relationship of C1> C2 is satisfied.

Furthermore, another conductive endless belt according to the present invention is disposed between the four types of image forming bodies and the recording medium, and is circulated by a driving member to be formed on the surface of the four types of image forming bodies. In the conductive endless belt for a tandem intermediate transfer member that sequentially transfers and holds the toner images to the surface of the toner, and transfers the toner images to a recording medium.
The maximum value of the surface potential after 1 second when the surface was charged with an applied voltage of 8 kV using a corona discharge device arranged at a distance of 1 mm from the belt surface was C1 on the front side and C2 on the back side. In this case, the relationship of C1> C2 is satisfied.

The difference between the maximum value C1 of the surface potential on the front side and the maximum value C2 of the surface potential on the back side is preferably 50 to 200 V, and the maximum value C1 of the surface potential on the front side is preferably 100 ~ 250V. Moreover, the volume resistance value when 100 V is applied is preferably 10 ⁷ to 10 ¹⁴ Ω · cm.

  The image forming apparatus of the present invention is characterized by using the conductive endless belt of the present invention.

  According to the conductive endless belt of the present invention, the relationship between the charge attenuation speeds on the front side and the back side of the belt surface is defined as described above, thereby preventing toner diffusion while ensuring high transfer efficiency. The reduction can be prevented, and sufficient static neutralization performance can be secured for the entire belt, and problems such as the occurrence of image defects due to residual charges can be prevented. Accordingly, since uniform charging can be obtained even during continuous printing or partial image printing, the image forming apparatus of the present invention using such a conductive endless belt can obtain a high-quality image with high transfer efficiency. It becomes possible.

Hereinafter, preferred embodiments of the present invention will be described in detail.
In general, the conductive endless belt includes a jointed belt and a jointless belt (so-called seamless belt), but any one may be used in the present invention. A seamless belt is preferable. As described above, the conductive endless belt of the present invention can be used as a transfer member for a tandem system, an intermediate transfer system, and a tandem intermediate transfer system.

  When the conductive endless belt of the present invention is, for example, a transfer conveyance belt indicated by reference numeral 10 in FIG. 2, the toner is sequentially transferred onto a recording medium that is driven by a driving member such as a driving roller 9 and the like. As a result, a color image is formed.

  Further, when the conductive endless belt of the present invention is an intermediate transfer member indicated by reference numeral 20 in FIG. 3, for example, this is circulated by a driving member such as a driving roller 30 and a photosensitive drum (latent image holder) 11 and the recording medium 26 such as paper, the toner image formed on the surface of the photosensitive drum 11 is temporarily transferred and held, and then transferred to the recording medium 26. Note that the apparatus of FIG. 3 performs color printing by the intermediate transfer method as described above.

  Furthermore, when the conductive endless belt of the present invention is, for example, a tandem intermediate transfer member denoted by reference numeral 50 in FIG. 4, the developing units 54a to 54d including the photosensitive drums 52a to 52d and the recording medium 53 such as paper are provided. The four-color toner images formed on the surfaces of the photosensitive drums 52 a to 52 d are temporarily transferred and held, and then transferred to the recording medium 53. Are transferred to form a color image.

  The conductive endless belt of the present invention has a maximum value of the surface potential after 0.35 seconds when the surface is charged with an applied voltage of 8 kV using a corona discharge device disposed at a distance of 1 mm from the belt surface. When the front side is C1 and the back side is C2, it is characterized in that the relationship of C1 <C2 is satisfied. By defining the relationship between the maximum value of the surface potential on the front side and the back side of the belt as described above, in order to secure transfer efficiency and prevent toner diffusion, and to perform static elimination It is possible to achieve both the necessary low charge retention capability and obtain a high-quality image with high transfer efficiency.

  Here, the charge retention capability of the belt surface is usually examined by measuring the surface resistance by placing a pair of electrodes on the belt surface and applying a constant voltage between the two electrodes. Since current does not flow only on the surface but also inside the belt, an accurate evaluation of the belt surface cannot be performed. In addition, although improvement in accuracy by the four-terminal method has been proposed, in particular, in the case of a laminated belt composed of two or more layers, the surface layer is generally a very thin layer. It is difficult to characterize. Therefore, it is considered that the characteristic values obtained by these conventional measuring methods cannot accurately represent the charge retention ability of the belt surface.

  Therefore, in the present invention, as described above, the corona discharge is generated by applying a voltage of 8 kV to the corona discharger disposed at a distance of 1 mm from the belt surface, and the belt surface is charged by this. The charge retention ability of the belt surface was evaluated by the maximum value of the surface potential after 2 seconds. The measurement of the surface potential is 1 second after the charging due to the generation of corona discharge. It is difficult to measure the surface potential immediately after the charging by corona discharge, and the actual process in image formation is considered. In this case, although depending on the image forming method, the rotation speed of the belt is usually 1 sec / 1 rotation.

  In the present invention, it is essential only that the maximum value of the surface potential on the front side and the back side satisfies the above relationship, and the absolute value is not particularly limited, but preferably the maximum value of the surface potential on the front side The difference between the value C1 and the maximum value C2 of the surface potential on the back side is 50 to 200V. By making the difference between C1 and C2 within the above range, the effect of the present invention can be most favorably obtained. Further, the maximum value C1 of the surface potential on the front side is preferably 100 to 250V, and if the maximum value C1 of the surface potential on the front side is less than 100V, the charge holding ability is lowered, the transfer efficiency is lowered, and the image quality is lowered. On the other hand, when the voltage exceeds 250 V, there is a possibility that an image defect due to residual charge may occur.

The volume resistance value of the belt of the present invention when applied with 100 V under an environment of 22 ° C. and 50% RH is preferably about 10 ⁷ to 10 ¹⁴ Ω · cm from the viewpoint of charging and transfer. .

  The material of the belt of the present invention is not particularly limited, and may be appropriately selected from conventional materials. It is preferable to use a thermoplastic resin from the viewpoint that it can be extruded. For example, a thermoplastic polyalkylene naphthalate resin such as a thermoplastic polyethylene naphthalate (PEN) resin or a thermoplastic polybutylene naphthalate (PBN) resin. Preferred examples include thermoplastic polyamide (PA), acrylonitrile-butadiene-styrene (ABS) resin, thermoplastic polyacetal (POM), thermoplastic polyarylate (PAR), and thermoplastic polycarbonate (PC). Also, polymer alloys or polymer blends of these thermoplastic resins and thermoplastic elastomers can be used, and by using any of these as a base material, it has good strength, particularly good bending durability. Can get a belt.

In the belt of the present invention, conductivity can be imparted and adjusted by adding a conductive material as a functional component to the base material as desired. Such conductive materials include, for example, lauryltrimethylammonium, stearyltrimethylammonium, octadecyltrimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, modified fatty acid / dimethylethylammonium perchlorate, chlorate, borofluoric acid Cationic surfactants such as quaternary ammonium such as salts, sulfates, ethosulphate salts, benzyl halide salts (such as verzyl bromide and benzyl chloride); aliphatic sulfonic acids, higher alcohol sulfates, higher Anionic surfactants such as alcohol ethylene oxide addition sulfates and higher alcohol phosphates; amphoteric surfactants such as various betaines; higher alcohol ethylene oxides, polyethylene glycol fatty acid esters Le, polyhydric alcohol fatty acid ester antistatic agent such as a nonionic antistatic agents such _{as, LiCF 2 SO 2, NaClO 4} , LiBF 4, periodic table Group 1 metal salts such as NaCl; Ca (ClO ₄₎ Metal salts belonging to Group 2 of the Periodic Table such as _{2 and the} like, and those antistatic agents having one or more groups having active hydrogen (hydrogen group, carboxyl group, primary or secondary amine group, etc.) that react with isocyanate Etc. Furthermore, ions of these and complexes with polyhydric alcohols (1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol, etc.) or derivatives thereof, or complexes with ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc. Conductive agent; conductive carbon such as ketjen black, acetylene black; carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT; carbon for oxidized color ink, pyrolytic carbon, Examples thereof include natural graphite, artificial graphite and the like; metals and metal oxides such as tin oxide, titanium oxide, zinc oxide, nickel and copper; and conductive polymers such as polyaniline, polypyrrole and polyacetylene.

  The addition amount of these ionic conductive agents or electronic conductive agents is preferably 0.1 to 100 parts by weight, more preferably about 1 to 50 parts by weight with respect to 100 parts by weight of the base material.

  In addition, a polymer ion conductive agent can be used as the conductive material. Examples of the polymeric ion conductive agent that can be used in the present invention include those described in JP-A-9-227717, JP-A-10-120924, and JP-A-2000-327922. However, it is not particularly limited.

Specifically, mention may be made of a mixture comprising (A) an organic polymer material, (B) an ionically conductive polymer or copolymer, and (C) an inorganic or low molecular weight organic salt, wherein component (A) ) Is a polyacrylic ester, polymethacrylic ester, polyacrylonitrile, polyvinyl alcohol, polyvinyl acetate, polyamide, polyurethane or polyester, component (B) is an oligoethoxylated acrylate or methacrylate, oligoethoxylated for aromatic rings Styrene, polyether urethane, polyether urea, polyether amide, polyether ester amide or polyether ester, and component (C) is an alkali metal or alkaline earth metal of an inorganic or low molecular weight organic protonic acid , A lead or ammonium salt, _{preferably, LiClO 4, LiCF 3 SO 3} , NaClO 4, LiBF 4, NaBF 4, KBF 4, NaCF 3 SO 3, KClO 4, KPF 6, KCF 3 SO 3, KC 4 F 9 SO ₃ , Ca (ClO ₄ ) ₂ , Ca (PF ₆ ) ₂ , Mg (ClO ₄ ) ₂ , Mg (CF ₃ SO ₃ ) ₂ , Zn (ClO ₄ ) ₂ , Zn (PF ₆ ) ₂ or Ca (CF ₃ SO ₃ ) ₂ etc.

Among these, as the component (B), a polymer ionic conductive agent containing a polyether amide component or a polyether ester amide component is suitable, and in addition to this, a low molecular ionic conductive agent component as the component (C). It is preferable to contain. Further, as the polyether amide component and the polyether ester amide component, those in which the polyether component contains (CH ₂ —CH ₂ —O) and the polyamide component contains nylon 12 or nylon 6 are particularly preferable. As a component (B), a polymer ion conductive agent containing NaClO ₄ as a low molecular ion conductive agent component of component (C) is particularly suitable. Such suitable polymer ion conductive agents are commercially available as Irgastat (registered trademark) P18 and Irgastat (registered trademark) P22 (both manufactured by Ciba Specialty Chemicals, Inc.) and Perestat NC6321 (manufactured by Sanyo Chemical Co., Ltd.). It can be obtained.

  The amount of the polymeric ionic conductive agent added is preferably about 1 to 500 parts by weight, more preferably about 10 to 400 parts by weight with respect to 100 parts by weight of the base material.

  In addition, when adding a polymeric ionic conductive agent to the conductive endless belt of the present invention, a compatibilizing agent may be added in order to improve the compatibility between the base material and the polymeric ionic conductive agent. Examples of compatibilizers that can be suitably used in the present invention include EVA / EPDM / polyolefin graft copolymers, polyolefin graft copolymers, and reactive (GMA and MAH-containing) polyolefin graft copolymers, P (St-co- GMA), EGMA, P (Et-co-EA-co-MAH), olefinic graft copolymer, maleated polyolefin, SEBS and its maleated product, oxazoline group-containing styrene-based or acrylonitrile-styrene-based polymer, maleated EPDM, maleic PE, maleated PP, maleated EVA, styrene / maleic anhydride copolymer, SAN grafted EPDM, reactive polystyrene, polycaprolactone-b-polystyrene, reactive styrene acrylic Ronitrile copolymer, imidized polyacrylate, ethylene / glycidyl methacrylate acrylic acid copolymer, chlorinated polyethylene, reactive phenoxy, silane compound, peroxide polymer, polycaprolactone, EVA / EPDM / polyolefin graft polymer, etc. Are abbreviated as EVA: ethylene vinyl acetate copolymer, EPDM: ethylene-propylene-diene copolymer, EGMA: ethylene-glycidyl methacrylate copolymer, SEBS: styrene-ethylene-butadiene-styrene copolymer, GMA: glycidyl methacrylate, MAH: maleic anhydride, EA: ethyl acrylate) and the like. These compatibilizers are used in a total amount of 100 parts by weight of the base material and the polymeric ion conductive agent. Preferably, by adding 0.1 to 20 parts by weight, the compatibility of both is improved, and the polymer ion conductive agent can be uniformly and satisfactorily dispersed in the base material. Obtainable.

  Further, in the belt of the present invention, other functional components can be appropriately added in addition to the above-mentioned components within a range not impairing the effects of the present invention. For example, various fillers, coupling agents, Antioxidants, lubricants, surface treatment agents, pigments, ultraviolet absorbers, antistatic agents, dispersants, neutralizing agents, foaming agents, crosslinking agents, and the like can be appropriately blended. Furthermore, a coloring agent may be added to color the belt.

  As long as the belt of the present invention satisfies the relationship between the front side and the back side of the maximum value of the surface potential, two or more layers are laminated even if it has a single layer structure composed of one layer. It may be a laminated structure and is not particularly limited. In the case of a laminated structure, two or more layers having different compositions may be laminated, or two or more layers having the same composition may be included.

  The thickness of the conductive endless belt of the present invention is appropriately selected according to the form of the transfer / conveying belt or the intermediate transfer member, but is preferably in the range of 50 to 200 μm. The surface roughness is preferably 10 μm or less, particularly 6 μm or less, more preferably 3 μm or less in terms of JIS 10-point average roughness Rz.

  Further, the conductive endless belt of the present invention has a surface on the side in contact with a driving member such as the driving roller 9 or the driving roller 30 of FIG. 3 in the image forming apparatus of FIG. 2, as shown by a one-dot chain line in FIG. A fitting portion that fits with a fitting portion (not shown) formed on the drive member may be formed, and the conductive endless belt of the present invention is provided with such a fitting portion and drives this. Shifting in the width direction of the conductive endless belt can be prevented by running with a fitting portion (not shown) provided on the member.

  In this case, the fitting portion is not particularly limited, but, as shown in FIG. 1, it is formed as a ridge continuous along the circumferential direction (rotation direction) of the belt, and this is a driving member such as a driving roller. It is preferable to be fitted in a groove formed in the circumferential surface along the circumferential direction.

  In addition, although the example which provided one continuous protruding item | line as a fitting part was shown in Fig.1 (a), this fitting part has many convex parts along the circumferential direction (rotation direction) of a belt. They may be arranged in a row, or two or more fitting portions may be provided (FIG. 1 (b)), or may be provided at the center in the width direction of the belt. Further, a groove along the circumferential direction (rotating direction) of the belt is provided as a fitting portion instead of the convex strip shown in FIG. 1, and this is formed along the circumferential direction on the circumferential surface of the driving member such as the driving roller. You may make it make it fit with the protruding item | line which carried out.

  Further, as the image forming apparatus of the present invention using the conductive endless belt of the present invention, the tandem system shown in FIG. 2, the intermediate transfer system shown in FIG. 3, or the tandem intermediate transfer system shown in FIG. Although the thing can be illustrated, it is not limited to these. In the case of the apparatus shown in FIG. 3, a voltage can be appropriately applied from the power source 61 to the driving roller or driving gear for rotating the intermediate transfer member 20 of the present invention. The application conditions such as application of weighting alternating current can be selected as appropriate.

  Further, the method for producing the conductive endless belt of the present invention is not particularly limited, and can be obtained, for example, by kneading a resin material as a main component and a functional component such as a conductive material by a biaxial kneader. The kneaded product can be produced by extrusion molding using an annular die. Alternatively, a powder coating method such as electrostatic coating, a dip method, or a centrifugal casting method can also be suitably employed.

Hereinafter, the present invention will be described in more detail with reference to examples.
Examples 1 to 3 and Comparative Examples 1 and 2
Each compounding component shown in the following Table 1 was melt-kneaded with a twin-screw kneader at the kneading temperature shown in the same table to obtain a kneaded product used for each of the front side and the back side. The obtained kneaded material is extruded using a two-layer coextrusion annular die with a single-screw extruder at the molding temperature shown in the table, and has an inner diameter of 220 mm, a thickness of 100 μm, and a width of 250 mm. Was made. The thickness ratio between the front side and the back side is as shown in the following table.

The physical properties of the obtained belts of the examples and comparative examples were measured according to the following procedures.
<Measurement of volume resistance>
At a temperature of 23 ° C. and a relative humidity of 50%, the volume resistivity at a measurement voltage of 100 V was measured using a resistance meter R8340A manufactured by ADVANTEST as a measuring device and a sample chamber R12704A connected thereto.

<Measurement of surface potential>
Using a CRT2000 device manufactured by QEA, a corona discharge was generated by applying a voltage of 8 kV to a scorotron discharger disposed at a distance of 1 mm from the belt surface, charging the belt surface, and the surface potential after 1 second. Maximum values were measured for both front and back sides. The measurement was carried out in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50%.

<Evaluation of image characteristics>
Each belt was mounted on a tandem type image forming apparatus using the transfer conveyance belt shown in FIG. 2, and the image characteristics after initial printing and after printing 100,000 sheets were evaluated.
These evaluation results are also shown in Table 1 below.

＊１）ＰＢＮ：帝人化成（株）製、商品名 ＴＱＢ−ＯＴ
＊２）ＰＥＴ：ユニチカ（株）製、商品名 ＳＡ−１２０６
＊３）ＰＡ１２：宇部興産（株）製、商品名 ３０２４Ｕ
＊４）ポリエステルエラストマー：東洋紡績（株）製、商品名 ペルプレンＰ−３０Ｂ
＊５）ポリウレタンエラストマー：協和発酵工業（株）製、商品名 エステン５８２７１
＊６）カーボンブラック：電気化学工業（株）製、型番 電化ブラック
＊７）高分子イオン導電剤：チバ・スペシャルティ・ケミカルズ・インコーポレーテッド製、Ｉｒｇａｓｔａｔ Ｐ１６

* 1) PBN: manufactured by Teijin Chemicals Ltd., trade name: TQB-OT
* 2) PET: Unitika Co., Ltd., trade name SA-1206
* 3) PA12: Ube Industries, Ltd., product name 3024U
* 4) Polyester elastomer: manufactured by Toyobo Co., Ltd., trade name: Perprene P-30B
* 5) Polyurethane elastomer: Kyowa Hakko Kogyo Co., Ltd., trade name: ESTEN 58271
* 6) Carbon black: manufactured by Denki Kagaku Kogyo Co., Ltd., model number: electrified black * 7) Polymer ion conductive agent: manufactured by Ciba Specialty Chemicals, Inc., Irgastat P16

It is width direction sectional drawing of the electroconductive endless belt which concerns on one embodiment of this invention. 1 is a schematic diagram illustrating a tandem type image forming apparatus using a transfer conveyance belt as an example of an image forming apparatus of the present invention. FIG. 6 is a schematic view showing an intermediate transfer device using an intermediate transfer member as another example of the image forming apparatus of the present invention. FIG. 5 is a schematic view showing a tandem intermediate transfer device using a tandem intermediate transfer member as another example of the image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11, 52a-52d Photosensitive drum 2, 7 Charging roll 3 Developing roll 4 Developing blade 5 Toner supply roll 6 Cleaning blade 8 Static elimination roll 9, 30, 55 Driving roller (driving member)
DESCRIPTION OF SYMBOLS 10 Transfer conveyance belt 12 Primary charger 13 Image exposure 14, 35 Cleaning device 19 Paper feed cassette 20 Intermediate transfer member 25 Transfer roller 26, 53 Recording medium 29, 61 Power supply 41, 42, 43, 44 Developer 50 Tandem intermediate transfer member 54a to 54d First developing portion to fourth developing portion 56 Recording medium feeding roller 57 Recording medium feeding device 58 Fixing device 59 Power supply device (voltage applying means)

Claims (7)

Conductive endless belt for tandem transfer and conveyance, in which a recording medium held by electrostatic adsorption is circulated and driven by a driving member, conveyed to four types of image forming bodies, and each toner image is sequentially transferred to the recording medium. In
The maximum value of the surface potential after 1 second when the surface was charged with an applied voltage of 8 kV using a corona discharge device arranged at a distance of 1 mm from the belt surface was C1 on the front side and C2 on the back side. A conductive endless belt satisfying a relationship of C1> C2. The toner image formed between the image forming body and the recording medium is circulated and driven by a driving member, and 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. In the conductive endless belt for the intermediate transfer member
The maximum value of the surface potential after 1 second when the surface was charged with an applied voltage of 8 kV using a corona discharge device arranged at a distance of 1 mm from the belt surface was C1 on the front side and C2 on the back side. A conductive endless belt satisfying a relationship of C1> C2. Arranged between the four types of image forming bodies and the recording medium, and circulated and driven by a driving member, and sequentially transferring and holding the toner images formed on the surfaces of the four types of image forming bodies on the surface of the recording medium. In a conductive endless belt for a tandem intermediate transfer member that transfers this to a recording medium,
The maximum value of the surface potential after 1 second when the surface was charged with an applied voltage of 8 kV using a corona discharge device arranged at a distance of 1 mm from the belt surface was C1 on the front side and C2 on the back side. A conductive endless belt satisfying a relationship of C1> C2.   The conductive endless belt according to any one of claims 1 to 3, wherein a difference between a maximum value C1 of the surface potential on the front side and a maximum value C2 of the surface potential on the back side is 50 to 200V.   The conductive endless belt according to any one of claims 1 to 4, wherein a maximum value C1 of the surface potential on the front side is 100 to 250V. The conductive endless belt according to any one of claims 1 to 5, which has a volume resistance value of 10 ⁷ to 10 ¹⁴ Ω · cm when 100 V is applied.   An image forming apparatus using the conductive endless belt according to claim 1.

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