JP2005266338A - Image forming apparatus, intermediate transfer body, processing method for intermediate transfer body, conductive rotating member and processing method for conductive rotating member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of stably forming a high-quality image, and to provide processing methods for an intermediate transfer body and a conductive rotating member to obtain the intermediate transfer body and the conductive rotating member which are inexpensive, whose change over time in electric resistance is small and whose lives are prolonged even in the case of using material whose calcining temperature is low. <P>SOLUTION: An intermediate belt 21 is processed and stabilized by using a stabilizing processing device 20 constituted of: the intermediate transfer belt 21 circularly moving; a ground roll 23; and a power source 25, and repeating a contact step of bringing plain paper 24 into contact with the intermediate belt 21 in a state where bias voltage from the power source 25 is applied while making the plain paper 24 intervene between the intermediate belt 21 and the ground roll 23, and a peeling step of peeling the plain paper 24 from the intermediate belt 21 with which the paper 24 is brought into contact in the contact step. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a laser printer, a facsimile, or a composite OA apparatus thereof, an intermediate transfer member used in these image forming apparatuses, a conductive rotating member, and an intermediate transfer member. The present invention relates to a method and a method for treating a conductive rotating member.

  In an electrophotographic image forming apparatus, a uniform charge is applied to an image carrier formed of a photoconductive photosensitive member made of an inorganic or organic material, and laser light or the like that modulates an image signal is applied to the image carrier. After irradiation to form an electrostatic latent image, the electrostatic latent image is developed with charged toner to form a toner image. The toner image is electrostatically transferred to a recording medium such as recording paper through an intermediate transfer member, thereby obtaining a desired reproduced image.

  Various types of image forming apparatuses have been proposed. For example, a toner image formed on an image carrier is primarily transferred to an intermediate transfer body, and then the intermediate transfer is performed. 2. Description of the Related Art An image forming apparatus that employs a system that secondarily transfers a toner image on a body onto a recording sheet is known (see, for example, Patent Document 1).

  Materials used for the intermediate transfer body of this intermediate transfer type image forming apparatus include polycarbonate resin, PVDF (polyvinylidene fluoride), polyalkylene phthalate, blend material of PC (polycarbonate) / PAT (polyalkylene terephthalate), ETFE ( Proposals have been made to use an endless belt in which conductivity is imparted to a thermoplastic resin such as an ethylene tetrafluoroethylene copolymer) / PC, ETFE / PAT, or PC / PAT blend material (see, for example, Patent Documents 2 to 7). ).

  However, the conductive materials of thermoplastic resins such as polycarbonate resin and PVDF (polyvinylidene fluoride) are inferior in mechanical properties, so the belt deformation with respect to stress during driving is large, and high quality transfer image quality can be obtained stably. There is a problem that can not be. In addition, there is a problem that the life of the belt is short because cracks are generated from the belt end during driving.

  Further, as an intermediate transfer belt material used in an image forming apparatus employing an intermediate transfer method, an elastic belt with a reinforcing material formed by laminating a woven fabric such as polyester and an elastic member has been proposed (for example, Patent Documents). (See 8, 9).

  However, the above-described elastic belt with a reinforcing material may have a problem of color misregistration due to creep deformation of the belt material over time. Therefore, as a semiconductive belt that can be used for such an intermediate transfer belt or a transfer conveyance belt, an intermediate transfer belt in which a conductive filler is dispersed in a polyimide resin having excellent mechanical properties and heat resistance has been proposed. (For example, refer to Patent Documents 10 and 11.)

  However, the semiconductive belt made of a single layer polyimide resin proposed so far has a poor balance between flexibility and rigidity, and cannot be said to satisfy the characteristics as an intermediate transfer belt or a transfer conveyance belt. . For example, in the belt of Patent Document 11, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, p-phenylenediamine, and polyamic acid (U varnish-S), which is a polymer, are used as raw materials for polyimide resin. Although a belt in which conductive filler is dispersed is disclosed, this type of intermediate transfer belt has a surface microhardness of 40 or more and excellent mechanical properties, but the pressing force tends to concentrate. There's a problem. That is, the bias roller is used to press the intermediate transfer belt against the image carrier carrying the toner image, and the toner image is electrostatically transferred by applying an electric field to the bias roller of the intermediate transfer belt. The deformation due to the pressing force is small, and the pressing force due to the bias roll tends to concentrate on the intermediate transfer belt. For this reason, the toner agglomerates and the charge density increases, causing discharge inside the toner layer and changing the polarity of the toner, thereby causing a problem of generating an image quality defect in which the line image is lost (holocharacter). Sometimes.

  Conventionally, in order to obtain a high-quality transfer image, the electrical resistance value of the intermediate transfer member is controlled within a predetermined range, and the in-plane variation (maximum and minimum resistance values) of the intermediate transfer member. It is known that the electrical resistance value does not change greatly even if the applied voltage changes, and that the electrical resistance value does not vary with time in the long-term durability test. When ordinary carbon black is dispersed as a conductive fine powder in a polyimide resin, secondary agglomeration occurs and a conductive chain is easily formed, and the variation in electric resistance value tends to increase. Further, since the in-plane variation of the electric resistance value is large, concentration of the applied voltage occurs in the transfer portion, and there arises a problem that the electric resistance value is lowered by the applied voltage. Specifically, for example, when a sheet of paper shorter than the width of the intermediate transfer member such as a postcard is continuously transferred and 1000 sheets or more are transferred, a halftone (30% magenta) image is transferred. White spots may occur in some parts.

  This image defect due to white spots is caused by the fact that as an intermediate transfer member of an image forming apparatus, a polycarbonate resin in which carbon black is dispersed or a thermoplastic resin such as an ethylene tetrafluoroethylene copolymer in which carbon black is dispersed, and carbon black dispersion. When using a polyimide resin or the like, when transferring a halftone image after continuously transferring 1000 sheets or more of a paper shorter than the width of the intermediate transfer body such as a postcard in a low temperature and low humidity environment of 10 ° C. and 15% RH. It occurs remarkably.

  As described above, white spots occur in the paper running section because the surface resistivity of the intermediate running body in the intermediate transfer body is caused by peeling discharge between the intermediate transfer body and the paper when the paper is peeled off in the secondary transfer section. The cause is considered to be that the transfer efficiency is lower than that of the peripheral part.

  Here, the reduction in resistance due to the transfer voltage of the intermediate transfer member and the occurrence of white spots due to the reduction in resistance of the intermediate transfer member will be described with reference to FIGS.

FIG. 4 is a schematic diagram for explaining a decrease in resistance in the secondary transfer portion of the intermediate transfer member.
As shown in FIG. 4, plain paper 104 as a transfer target is placed on a nip portion (secondary transfer portion) formed between a support roll 102 and a transfer roll 103 via a belt-shaped intermediate transfer belt 101. At the same time as passing, secondary transfer is performed by applying a transfer voltage from the bias power source 105. Immediately after the secondary transfer, when the intermediate transfer belt 101 and the plain paper 104 are separated, a discharge is generated from the intermediate transfer belt 101 to the plain paper 104 side. Due to this discharge phenomenon, the surface of the intermediate transfer belt 101 is altered, a new conductive path is formed, and the resistance is lowered. Further, when the electric field dependency is large, the electric field concentration occurs on the surface of the intermediate transfer belt 101, and the surface of the intermediate transfer belt 101 is easily deteriorated, so that the resistance is further reduced.

  FIG. 5 is a diagram illustrating a state in which the sheet running portion of the intermediate transfer member has been deteriorated due to a decrease in resistance.

  When a 30% magenta halftone toner image formed on the intermediate transfer belt 200 is transferred onto plain paper, as shown in FIG. At the time of transfer after that, as shown in FIG. 5B, no abnormality occurs in the non-paper running portion 202 on the intermediate transfer belt 200, but there is no white spot in the portion corresponding to the paper running portion 201. Will occur.

  The above resistance reduction often depends on carbon black contained in the intermediate transfer belt. For example, when the dispersibility of carbon black is poor, the resistance reduction tends to increase. This decrease in resistance leads to shortening of the life of the intermediate transfer member, and may increase the maintenance effort and running cost, which is not preferable.

Therefore, as a solution to the problems in the prior art, there is little deformation due to driving, resistance drop due to transfer voltage is prevented, uniformity of electrical resistance is improved, electric field dependency is less, and resistance change due to the environment An intermediate transfer member having a low content is disclosed (for example, see Patent Document 12). That is, it has a polyimide resin film containing oxidized carbon black, at least one of oxidized carbon black has a conductivity index of 15 or less, and a surface resistivity of 10 ¹⁰ to 10 ¹⁴ (Ω / □) It is an intermediate transfer member characterized by the above.

  However, in this intermediate transfer member, the reduction in resistance is improved by using oxidized carbon black. Although the resistance reduction is improved by oxidized carbon black, the effect of the firing temperature is large, but the oxidized carbon black is improved. Even in the case of using, a firing temperature of 350 ° C. or higher is necessary, and it cannot be said that this is a sufficient improvement from the viewpoint of manufacturing cost.

Further, as another conventional technique, it is composed of a polyimide resin containing a plurality of types of carbon blacks having different conductivity, and at least one of those carbon blacks is oxidized carbon black, and the common logarithm of surface resistivity is used. Is an intermediate transfer member having a surface resistivity of 1.5 (log Ω / □) when a voltage of 100 V or 1000 V is applied to the intermediate transfer member. ) Is disclosed (for example, see Patent Document 13).
JP-A-62-206567 (page 1-2, FIG. 4) JP-A-6-095521 (page 2-4, FIG. 5) Japanese Patent Laid-Open No. 5-200904 (page 2) JP-A-6-228335 (page 2-3, FIG. 4) Japanese Patent Laid-Open No. 6-149081 (2nd page, FIG. 4) Japanese Patent Laid-Open No. 6-149083 (second page, FIG. 4) Japanese Patent Laid-Open No. 6-149079 (page 2-3, FIG. 4) JP-A-9-305038 (page 2-3, FIG. 4) Japanese Patent Laid-Open No. 10-240020 (page 2-3, FIG. 5) JP-A-5-77252 (page 2-3, FIG. 4) JP-A-10-63115 (page 2-3, FIG. 4) JP 2001-324880 A (page 2-3, FIG. 4) JP 2002-148951 (page 2-3, FIG. 1)

  The technique of the above-mentioned Patent Document 13 improves the dispersibility of carbon black by previously dispersing oxidized carbon black in a solvent and improves the resistance reduction of the intermediate transfer member. In addition, a baking temperature of 300 ° C. or higher is necessary, and further improvement in manufacturing cost is strongly demanded.

  In view of the above circumstances, an object of the image forming apparatus of the present invention is to provide an image forming apparatus capable of stably forming a high-quality image.

  Another object of the intermediate transfer member of the present invention is to provide an intermediate transfer member that is inexpensive and has a long life with little change in electrical resistance over time.

  In addition, in view of the above circumstances, the intermediate transfer member processing method of the present invention is an intermediate transfer member that can obtain a long-life intermediate transfer member with little change in electrical resistance with time even when a material having a low firing temperature is used. An object is to provide a processing method.

  Another object of the conductive rotating member of the present invention is to provide an electrically conductive rotating member that is inexpensive and has a long life with little change in electrical resistance over time.

  In addition, in view of the above circumstances, the method for treating a conductive rotating member of the present invention is a conductive material capable of obtaining a long-lived conductive rotating member with little change in electrical resistance over time even when a material having a low firing temperature is used. It aims at providing the processing method of a rotating member.

The first image forming apparatus of the present invention that achieves the above object provides:
By an image forming cycle in which a toner image is carried on a toner image carrier that carries a toner image, and the toner image carried on the toner image carrier is transferred to a predetermined transfer surface and finally fixed on a recording medium. In an image forming apparatus for forming an image composed of a fixed toner image on a recording medium,
An intermediate transfer body having the transfer surface, which circulates in a state where the surface is in contact with the toner image carrier;
A bias applying unit that applies a predetermined bias to the intermediate transfer member when the image forming cycle is executed,
The intermediate transfer member is obtained by subjecting the surface to a conductive treatment by electric field stress.

  According to the first image forming apparatus of the present invention, since the change in electrical resistance of the intermediate transfer body with time is reduced by using the electrically conductive intermediate transfer body, color misregistration, holocharacter, white Occurrence of image defects such as omission is suppressed, and high-quality images can be stably obtained.

The intermediate transfer member of the present invention that achieves the above object is
The toner image is carried on a toner image carrier that carries the toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface, and finally fixed on the recording medium. In the intermediate transfer body having the above-mentioned transfer surface, which is disposed in an image forming apparatus for forming an image composed of a fixed toner image thereon and circulates in a state where the surface is in contact with the toner image carrier,
The intermediate transfer member is obtained by subjecting the surface to a conductive treatment by electric field stress.

  According to the intermediate transfer member of the present invention, by using the intermediate transfer member that has been subjected to the conductive treatment, an intermediate transfer member that is inexpensive and has a long life with little change in electrical resistance with time can be obtained.

In addition, the method for treating an intermediate transfer member of the present invention that achieves the above-described object is as follows.
The toner image is carried on a toner image carrier that carries the toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface, and finally fixed on the recording medium. In the processing method of the intermediate transfer member having the transfer surface, which is provided in an image forming apparatus for forming an image composed of a fixed toner image on the surface and circulates and moves while the surface is in contact with the toner image carrier.
A contact step of bringing the surface of the intermediate transfer member into contact with a high resistance member having a higher resistance than the intermediate transfer member;
A peeling step of peeling both in a state where an electric field is applied between the surface of the intermediate transfer member contacted in the contact step and the high resistance body,
The contact step and the peeling step are repeatedly performed.

  According to the method for treating an intermediate transfer member of the present invention, the electrical resistance is stabilized by repeatedly performing the contact step and the peeling step, and the life of the intermediate transfer member can be extended.

The second image forming apparatus of the present invention that achieves the above object provides:
By an image forming cycle in which a toner image is carried on a toner image carrier that carries a toner image, and the toner image carried on the toner image carrier is transferred to a predetermined transfer surface and finally fixed on a recording medium. In an image forming apparatus for forming an image composed of a fixed toner image on a recording medium,
A conductive rotating member that rotates while the surface is in contact with the toner image carrier;
A bias applying unit that applies a predetermined bias to the conductive rotating member when the image forming cycle is executed,
The conductive rotating member is subjected to a conductive treatment by electric field stress.

  Here, the conductive rotating member in the second image forming apparatus of the present invention specifically refers to a member such as a charging roll or a transfer roll.

  According to the second image forming apparatus of the present invention, the use of the conductive rotating member that has been subjected to the conductive treatment reduces the change over time in the electrical resistance of the conductive rotating member. The occurrence of image defects such as white spots is suppressed, and high-quality images can be stably obtained.

The conductive rotating member of the present invention that achieves the above object is
A toner image is carried on a toner image carrier that carries a toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface, and finally fixed on a recording medium, and then the recording medium In a conductive rotating member that is disposed in an image forming apparatus that forms an image composed of a fixed toner image on the surface and rotates while the surface is in contact with the toner image carrier,
The conductive rotating member is subjected to a conductive treatment by electric field stress.

  According to the conductive rotating member of the present invention, by using the conductive rotating member that has been subjected to the conductive treatment, it is possible to obtain a conductive rotating member that is inexpensive and has a long life with little change in electrical resistance over time.

Moreover, the processing method of the conductive rotating member of the present invention that achieves the above-described object is as follows.
The toner image is carried on a toner image carrier that carries the toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface, and finally fixed on the recording medium. In a processing method of a conductive rotating member that is disposed in an image forming apparatus that forms an image composed of a fixed toner image thereon and rotates while the surface is in contact with the toner image carrier,
A contact step of bringing the conductive rotating member into contact with the high resistance body;
A peeling step of peeling both of the conductive rotating member brought into contact in the contact step and the high resistance body in a state where an electric field is applied,
The contact step and the peeling step are repeatedly performed.

  According to the processing method of the conductive rotating member of the present invention, the electrical resistance is stabilized by repeatedly performing the contact step and the peeling step, and the life of the conductive rotating member can be extended.

  As described above, according to the first image forming apparatus of the present invention, by using the intermediate transfer body that has been subjected to the stabilization process, there is little change in electrical resistance of the intermediate transfer body over time, and high-quality images can be obtained. An image forming apparatus that can be stably formed can be realized.

  In addition, according to the intermediate transfer member of the present invention, by using the intermediate transfer member that has been subjected to the stabilization treatment, it is possible to realize an intermediate transfer member that is inexpensive and has a long life with little change in electrical resistance over time. it can.

  Further, according to the method for treating an intermediate transfer member of the present invention, a long-life intermediate transfer member with little change in electrical resistance with time can be stably obtained even when a material having a low firing temperature is used. Moreover, high energy consumption by the conventional high-temperature baking treatment can be reduced, and excellent performance, high productivity, and low cost can be realized.

  In addition, according to the second image forming apparatus of the present invention, by using the conductive rotating member subjected to the stabilization process, the electrical resistance of the conductive rotating member is little changed with time, and a high-quality image is stabilized. Thus, an image forming apparatus that can be formed can be realized.

  In addition, according to the conductive rotating member of the present invention, by using the conductive rotating member that has been subjected to stabilization treatment, a low-cost conductive rotating member that has little change in electrical resistance with time is realized. can do.

  In addition, according to the method for treating a conductive rotating member of the present invention, even when a material having a low firing temperature is used, a long-lived conductive rotating member with little change in electrical resistance with time can be stably obtained. Moreover, high energy consumption by the conventional high-temperature baking treatment can be reduced, and excellent performance, high productivity, and low cost can be realized.

  Embodiments of the present invention will be described below with reference to the drawings.

  Next, an embodiment of the image forming apparatus of the present invention will be described.

  FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the image forming apparatus of this embodiment forms an electrostatic latent image based on image information on an image carrier charged by a charging roll, and develops the electrostatic latent image with toner. An intermediate in which a toner image is formed, the toner image is primarily transferred onto an intermediate transfer member, the toner image transferred onto the intermediate transfer member is secondarily transferred to a transfer member, and the toner image is fixed on a recording medium. This is a transfer type image forming apparatus.

  The image forming apparatus of the present invention is not particularly limited as long as it is an intermediate transfer body type image forming apparatus. For example, a monocolor image forming apparatus containing only a single color toner in a developing device, A color image forming apparatus that sequentially repeats primary transfer of a toner image carried on an image carrier to an intermediate transfer member, and a tandem type in which a plurality of image carriers equipped with developing units for each color are arranged in series on the intermediate transfer member A color image forming apparatus is exemplified.

  As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment includes an image carrier 9 for each color, which includes four color developing devices 15 of black, yellow, magenta, and cyan, on a rotating intermediate transfer member 16. A full-color image forming apparatus in contact with and arranged in tandem, a charging roll 13 (charging device) that uniformly charges the surface of the image carrier 9, and a laser that exposes the surface of the image carrier 9 to form an electrostatic latent image A generating device 8 (exposure device), a developing device 15 (developing device) for developing the electrostatic latent image formed on the surface of the image carrier 9 using a developer to form a toner image, and a toner image on the image carrier 9 A primary transfer roll 10 (primary transfer means) that transfers the toner to the intermediate transfer body 16, support rolls 3 and 4 that support the intermediate transfer body 16, a drive roll 11 that drives the intermediate transfer body 16, and a toner image on the intermediate transfer body 16. From the paper tray 7 Secondary transfer roll 5 (secondary transfer means) for transferring to the recording medium 6, fixing roll 2 (fixing device) for fixing the toner image on the recording medium 6, toner or dust adhering to the image carrier 9, etc. A cleaning device such as a belt cleaner 12 that removes toner or dust adhering to the photoconductor cleaner 14 and the intermediate transfer member 16 can be provided as necessary.

  The conductive rotating member of the present invention can be used as at least one member such as the charging roll 13 and the secondary transfer roll 5 of the image forming apparatus. Details of the conductive rotating member will be described later.

  As the image carrier 9, a conventionally known one can be used, and as the photosensitive layer on the surface thereof, a known one such as organic or amorphous silicon can be used. When the image carrier is cylindrical, it can be obtained by a known production method such as surface processing after extrusion molding of aluminum or an aluminum alloy. It is also possible to use the belt-shaped image carrier.

  The charging device is not particularly limited, and examples thereof include a contact type charger using a conductive or semiconductive roll, brush, film, rubber blade, a scorotron charger using a corona discharge, a corotron charger, and the like. A charger known per se can be used. Among these, a contact-type charger is preferable in terms of excellent charge compensation capability. This charging device normally applies a direct current to the photoconductor, but may apply a direct current superimposed with an alternating current.

  The exposure apparatus is not particularly limited. For example, a light source such as a semiconductor laser light, an LED light, or a liquid crystal shutter light on the surface of the photosensitive member, or an optical system capable of exposing a desired image from these light sources through a polygon mirror. Examples include equipment.

  The developing device can be appropriately selected according to the purpose. For example, a known developing device that develops a one-component developer or a two-component developer in a contact or non-contact manner using a brush, a roll, or the like. Is mentioned.

  Examples of the primary transfer means include known transfer chargers such as contact transfer chargers using belts, rolls, films, rubber blades, scorotron transfer chargers using corona discharge, and corotron transfer chargers. Can be mentioned. Among these, a contact type transfer charger is preferable in that it has excellent transfer charge compensation capability. In the image forming apparatus of the present invention, a peeling charger or the like can be used in combination with the transfer charger.

  Examples of the secondary transfer unit include a contact transfer charger such as a transfer roll exemplified as the primary transfer unit, a scorotron transfer charger, a corotron transfer charger, and the like. Among these, it is preferable to use a contact type transfer charger as in the case of the primary transfer unit. It is preferable to strongly press with a contact type transfer charger such as a transfer roll because the image transfer state can be maintained in a good state. In addition, when a contact transfer charger such as a transfer roll is pressed at the position of the roll that guides the intermediate transfer member, the toner image can be transferred from the intermediate transfer member to the transfer target in a good state. become.

  The fixing device is not particularly limited, and examples thereof include known fixing devices such as a hot roll fixing device and an oven fixing device.

  There is no restriction | limiting in particular as a cleaning apparatus, A itself well-known cleaning apparatus etc. can be used.

  As described above, the image forming apparatus according to the present exemplary embodiment includes a conductive rotating member that is rotated in a state in which the surface is in contact with the toner image carrier and that has been subjected to a conductive treatment by electric field stress, and a surface on the toner image carrier. An intermediate transfer member that is circulated and moved in contact with the surface, and is subjected to surface stress treatment by electric field stress; and a bias application unit that applies a predetermined bias to each of the intermediate transfer member and the conductive rotating member during an image forming cycle. It is characterized by having

As described above, the intermediate transfer member and the conductive rotating member used in this image forming apparatus are subjected to a conductive treatment by an electric field stress, but the intermediate transfer member is made of a polyimide resin containing carbon black. And obtained by subjecting the surface to a conductive treatment. The conductive rotating member is preferably coated with an elastic layer in which conductive particles are dispersed and a protective resistance layer in which conductive particles are dispersed, and can be obtained by conducting a conductive treatment in the same manner as the intermediate transfer member. As an elastic layer of the conductive rotating member, a rubber such as polybutadiene, natural rubber, polyisoprene, butyl rubber, CR (chloroprene), NBR (nitrile butadiene rubber), BR (butadiene rubber), silicone rubber, epichlorohydrin, SBR (styrene- Butadiene rubber), SBS (styrene-butadiene-styrene elastomer) and other polystyrene-based, polyolefin-based, polyester-based, polyurethane-based, PVC (polyvinyl chloride), nitrile rubber and other thermoplastic elastomers, polyurethane, polystyrene, polyethylene, polypropylene Plastomer materials such as PVC, acrylic resin and styrene-vinyl acetate copolymer are used. Further, as the protective resistance layer resin, acrylic resin, cellulose resin, polyamide resin, polyimide resin, methoxymethylated nylon, ethoxymethylated nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, Polythiophene resins, polyolefin resins such as PFA, FEP, and PET, and styrene-butadiene resins are used. Conductive particles include metals such as zinc, aluminum, copper, iron, nickel, chromium and titanium, and tin oxide (S _n O ₂ ), zinc oxide (Z _n O), and indium oxide (In ₂ O ₃ ). , potassium titanate (K ₂ TiO _3), a metal oxide or carbon black such as S _n O ₂ -In ₂ O ₃ solid solution is used. In particular, the protective resistance layer is preferably a member obtained by dispersing carbon black in a polyimide resin from the viewpoint of quality stability and durability.

The intermediate transfer member and the conductive rotating member are made conductive by an intermediate transfer member used in an image forming apparatus, a conductive rotating member such as a charging roll and a transfer roll, and higher than the intermediate transfer member and the conductive rotating member. This is performed by repeating contact and peeling while applying a predetermined electric field between plain paper and the like of resistance. That is, a contact step in which the intermediate transfer member and the conductive rotating member are brought into contact with the high resistance high resistance member, and a surface of the intermediate transfer member and the conductive rotating member in contact in the contact step and the high resistance member. This is performed by repeatedly performing a peeling step of peeling both in the state where an electric field is applied. The high resistance body preferably has a surface resistivity of about 5 × 10 ⁹ Ω / □ to 1 × 10 ¹² Ω / □.

The electric field applied in this conductive treatment is a DC voltage of 1 KV to 10 KV controlled to a constant current value in the range of 10 μA to 100 μA under a low humidity condition of 2.7 g / m ³ or less of absolute humidity. It is preferable to carry out by applying.

  The decrease in the surface resistivity of the intermediate transfer member and the conductive rotating member occurs because a trace amount of impurities present in the intermediate transfer member and the conductive rotating member form an electric circuit due to discharge at the time of sheet peeling under low humidity. Guessed. This resistance fluctuation is stabilized when a certain resistance value is reached, but it is considered that the electric circuit density is saturated or the impurities in the intermediate transfer body and the conductive rotating member are completely consumed. In addition, since the discharge directly affects the formation of the electric circuit, the resistance fluctuation speed is increased under a high electric field and low humidity due to the influence of the electric field and humidity which are the causes of the discharge. Due to the conductive treatment, the resistance value is reduced to 50% or less, preferably 60% or less of the initial resistance value.

  Accordingly, by applying a high electric field stress under low humidity before using the intermediate transfer member and the conductive rotating member as members of the image forming apparatus, the intermediate transfer member and the conductive member during the use in the image forming apparatus are used. The resistance change with time of the conductive rotating member is reduced, and the performance of the intermediate transfer member and the conductive rotating member can be stably maintained.

  In addition, this eliminates the need for a long-time baking process using high-temperature thermal energy when manufacturing an intermediate transfer member and a conductive rotating member, and allows a lower-temperature baking process to be used. There is also an effect of saving.

  As an apparatus for stabilizing the intermediate transfer member and the conductive rotating member, for example, the following processing apparatus is optimal.

  FIG. 2 is a diagram showing a basic configuration of the stabilization processing apparatus for the intermediate transfer member and the conductive rotating member.

  As shown in FIG. 2, the stabilization processing device 20 is connected to the intermediate transfer belt 21 that rotates while being supported by the support roll 22, a grounding roll 23 that is disposed to face the support roll 22, and the support roll 22. Power source 25.

  In a state where plain paper 24 is interposed between the intermediate transfer belt 21 and the grounding roll 23 and a bias voltage from the power supply 25 is applied, the intermediate transfer belt 21 and the plain paper 24 are brought into contact with each other in the contact process. The intermediate transfer belt 21 and the peeling process for peeling the plain paper 24 are repeated to stabilize the intermediate transfer belt 21 by applying a high electric field stress.

  The bias voltage applied from the power supply 25 cannot be generally defined by the power supply method or the resistance of the power supply material, but is preferably controlled by the current value.

  The value of current passing through the intermediate transfer belt 21 is preferably 10 μA to 100 μA, and stabilization can be performed in a short time by using a large current, but the total thickness of the intermediate transfer belt 21 and the plain paper 24. Is normally about 150 μm to 600 μm, and if a large current is passed and the potential difference reaches 10 KV or more, the intermediate transfer belt 21 may be damaged. Specifically, when the current value exceeds 100 μA, although depending on the film thickness and the resistance value of the intermediate transfer belt 21, the possibility of causing dielectric breakdown of the intermediate transfer belt 21 becomes high, which is not preferable. On the other hand, when the current value is a small current value of less than 10 μA, the discharge is weak and a long time is required for the stabilization treatment, which is not preferable. More preferably, the current value is 30 μA to 100 μA.

Further, the humidity during the application of the electric field stress needs to be discharged in the air when the intermediate transfer member and the paper are peeled off, so it is desirable that the humidity is a low humidity condition of 2.7 g / m ³ or less in absolute humidity. More preferably, the absolute humidity is 1.3 g / m ³ or less.

The number of repetitions of the contact step and the peeling step is about 5000 times under the conditions of a current value of 20 μA and an absolute humidity of 2 g / m ³ , and about 200 times under the conditions of a current value of 40 μA and an absolute humidity of 2 g / m ³ . However, this is merely a guideline and varies depending on the absolute humidity, the power supply method, the power supply capability, etc., and is not limited to the above values.

  In the above-described stabilization processing apparatus 20, the intermediate transfer belt 21 has been described as an example, but the present invention can be similarly applied to a charging roll, a transfer roll, and the like of the image forming apparatus.

  The intermediate transfer member used in the image forming apparatus of the present embodiment and the conductive rotating member such as a charging roll and a transfer roll preferably have a transfer surface hardness of 30 or less in terms of surface microhardness, and 25 or less. It is more preferable. This surface microhardness does not use the method of obtaining the diagonal length of the indentation, unlike the Vickers hardness widely used for measuring the hardness of metal materials, but how much the indenter has entered the sample. It is obtained by measuring. When the test load is P (mN) and the indentation amount (indentation depth) of the indenter into the sample is D (μm), the surface microhardness DH is defined by the following formula (1).

DH≡αP / D ² (1)
Here, α is a constant depending on the shape of the indenter, and when the working indenter is a triangular pyramid indenter, α = 3.8854.

  This surface microhardness is the hardness obtained from the load and indentation depth in the process of indenting the indenter, and represents the strength characteristics of the material in a state including not only plastic deformation of the sample but also elastic deformation. Is. The measurement area of the surface microhardness is very small, and it is possible to measure the hardness more accurately within a range close to the toner particle diameter. The present inventors have found that there is a very clear correlation between the surface microhardness obtained here and the generation level of the holocharacter. In other words, when the surface microhardness of the transfer surface of the intermediate transfer member is preferably 30 or less, more preferably 25 or less, the intermediate transfer member is pressed by the bias roll pressing force in the secondary transfer portion of the image forming apparatus. The transfer surface is deformed, whereby the pressing force concentrated on the toner on the intermediate transfer member is dispersed. For this reason, the toner does not aggregate, and image quality defects such as holocharacters in which the line image disappears do not occur.

  The surface microhardness on the transfer surface of the intermediate transfer member can be obtained as follows. A sheet of material (surface layer) constituting the transfer surface is cut to about 5 mm square, and the small piece is fixed to the glass plate with an instantaneous adhesive. The surface microhardness of the surface of this sample is measured using an ultra micro hardness meter DUH-201S (manufactured by Shimadzu Corporation). The measurement conditions are as follows.

Measurement environment: 23 ° C 55% RH
Working indenter: Triangular pyramid indenter Test mode: 3 (soft material test)
Test load: 0.70 gf
Load speed: 0.0145 gf / sec
Holding time: 5 sec
In the case where the intermediate transfer member of the present embodiment is a belt-like one, the relationship of the following formula (2) is established between the belt Young's modulus and the amount of belt displacement due to disturbance (load fluctuation) during belt driving. It is desirable that

Δl = P · l · α / (t · w · E) (2)
here,
Δl: Belt displacement (μm)
P: Load (N)
l: Belt length between two tension rolls (mm)
α: coefficient t: belt thickness (mm)
w: Belt width (mm)
E: Young's modulus of belt material (N / mm ² )
It is.

  In the case of a belt-like intermediate transfer member, the belt expansion / contraction (displacement amount) due to disturbance (load fluctuation) during driving of the belt is inversely proportional to the Young's modulus and thickness of the belt material. When a belt material with a high Young's modulus is used, the amount of displacement of the belt due to disturbance (load fluctuation) during belt driving decreases, and belt deformation with respect to stress during driving decreases, so that good image quality can be stably obtained. It is preferable because it is possible. However, as the thickness of the belt increases, the amount of deformation of the outer surface of the belt at the belt bending portion such as the drive train roll increases, so that it becomes difficult to obtain good image quality, and the amount of deformation between the outside and inside of the belt And the belt may break due to local repeated stress, which is not preferable.

  In the case where the intermediate transfer member of the present embodiment is a belt, the total thickness of the belt is 0.05 mm to 0.5 mm, preferably 0.06 mm to 0.30 mm, and more preferably. 0.06 mm to 0.15 mm is desirable. When the total thickness of the belt is less than 0.05 mm, it becomes difficult to satisfy the required mechanical properties as an intermediate transfer body (belt). Deformation may cause problems such as concentration of stress on the belt surface and generation of cracks in the surface layer.

  Moreover, it is preferable that the ratio of the thickness of the outer layer and the intermediate layer of the belt is 10% to 50% of the total thickness. When the thickness of the outer layer and the intermediate layer of the belt is within the above range, the pressing force concentrated on the toner on the semiconductive belt is dispersed without affecting the resin material of the base material. The toner does not aggregate and image quality defects such as holocharacters in which the line image is lost do not occur. The Young's modulus of the material of the belt base layer varies depending on the thickness of the belt, but preferably 3500 MPa or more, more preferably 4000 MPa or more, the mechanical properties as a belt substrate can be satisfied.

  The resin material used as the intermediate transfer member and the conductive rotating member of the present embodiment is not particularly limited as long as it has a Young's modulus of 3500 MPa or more. Polyimide resin, polyamide resin, polyamideimide resin, polyether ether ester Examples thereof include a resin, a polyallelate resin, a polyester resin, and a polyester resin to which a reinforcing material is added.

  The intermediate transfer member and the conductive rotating member of this embodiment are mainly composed of a polyimide resin. However, since the polyimide resin is a high Young's modulus material, there is little deformation due to stress such as a support roll and a cleaning blade during driving. Therefore, image defects such as color misregistration are unlikely to occur, and it is suitable as an intermediate transfer member and a conductive rotating member.

  A polyimide resin is usually obtained as a polyamic acid solution by polymerizing a substantially equimolar amount of tetracarboxylic dianhydride or its derivative and a diamine in a solvent. As tetracarboxylic dianhydride, what is shown by the following general formula is mentioned, for example.

  R in the above general formula is a tetravalent organic group, and is an aromatic group, an aliphatic group, a cycloaliphatic group, a combination of an aromatic group and an aliphatic group, or a substituted group thereof.

  Specific examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, and 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Acid dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid Dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) sulfonic dianhydride, perylene-3,4,9,10 -Tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylenetetracarboxylic dianhydride, etc. are mentioned.

  On the other hand, specific examples of the diamine include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl4,4′-biphenyldiamine, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylpropane, 2,4-bis (β-aminotert-butyl) toluene, bis (p-β-amino-tertiary) Tributylphenyl) ether, bis (p-β-methyl-δ-aminophenyl) Benzene, bis-p- (1,1-dimethyl-5-amino-benzyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di (p- Aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11- Diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methyl Nonamethylene Diamine, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 12-diaminooctadecane, 2,2-bis [4- (4-aminophenoxy) Phenyl] propane, piperazine, H2N (CH2) 3O (CH2) 2O (CH2) NH2, H2N (CH2) 3S (CH2) 3NH2, H2N (CH2) 3N (CH3) 2 (CH2) 3NH2, and the like.

  As a solvent for the polymerization reaction of tetracarboxylic dianhydride and diamine, a polar solvent (organic polar solvent) is preferable from the viewpoint of solubility. As the polar solvent, N, N-dialkylamides are preferable, and specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, which are low molecular weight compounds thereof. N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylenesulfone, dimethyltetramethylenesulfone and the like. These can be used alone or in combination.

  In the stabilization processing apparatus 20 (see FIG. 2), the plain paper 24 has been described as an example of a high resistance body having higher resistance than the intermediate transfer body and the conductive rotating member. Is not limited to plain paper, and various types of paper such as the following can be used as the high resistance body. However, plain paper is preferable because it is a high resistance material under low humidity conditions, has flexibility, has good adhesion to the intermediate transfer member and the conductive rotating member, and can be obtained at low cost.

  Specifically, chemical pulp as raw material for paper, specifically hardwood bleached kraft pulp, hardwood unbleached kraft pulp, softwood bleached kraft pulp, softwood unbleached kraft pulp, hardwood bleached sulfite pulp, hardwood unbleached sulfite pulp, conifer Made from wood such as bleached sulfite pulp, softwood unbleached sulfite pulp, and pulp made by chemically treating fiber raw materials such as cotton, hemp, and leather, and mechanically processing wood and chips It is made from ground wood pulp that has been pulped, chemimechanical pulp that has been mechanically pulped after soaking chemicals into wood and chips, and thermomechanical pulp that has been digested to a slightly softer chip and then pulped with a refiner. Etc. These may be used only with virgin pulp, or may be used with added waste paper pulp. Moreover, in order to adjust opacity, whiteness, and surface property, what added the filler may be used. Fillers include heavy calcium carbonate, light calcium carbonate, calcium carbonate such as chalk, kaolin, calcined clay, silicic acid such as piorophyllite, sericite, talc, saponite, calcium montmorillonite, sodium montmorillonite, bentonite, etc. Examples thereof include inorganic fillers and organic fillers such as urea resin and starch fiber. Further, a surface sizing agent may be used. Examples of the surface sizing agent include rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, neutral sizing agents, starch, and polyvinyl alcohol.

  Moreover, what mixed the electrically conductive agent and adjusted the surface electrical resistance value of the paper may be used. Examples of the conductive agent include inorganic electrolytes such as sodium sulfate, sodium carbonate, lithium carbonate, sodium metasilicate, sodium tripolyphosphate, and sodium metaphosphate, anions such as sulfonate, sulfate ester salt, carboxylate, and phosphate. Nonionic surfactants such as ionic surfactants, cationic surfactants, polyethylene glycol, glycerin and sorbit, and amphoteric surfactants and polymer electrolytes.

  The characteristic values as general paper are described below. Although these are desirable characteristic values, they are guidelines for the paper used for the stabilization process, and are not limited to these.

First, the surface electrical resistance is a sheet that falls within a range of 5 × 10 ⁹ Ω to 1 × 10 ¹² Ω in a standard environment (temperature 23 ° C., relative humidity 50%) defined in JIS-P-8111-1998. It is desirable. In addition, a surface electrical resistance value can be measured with the measuring method of JIS-K-6911.

Moreover, in JIS-P-8124 basis weight due to the ^{75g / m 2 ~95g / m 2} , JIS-P-8119 by a Bekk smoothness of paper for both the front and rear 65 to 120 seconds, and, JIS-P-8118 It is preferable that the density is 0.80 g / cm ³ or more.

Also, the expansion ratio of CD (perpendicular to the paper machine traveling direction) when the temperature is changed from 20 ° C./humidity 65% RH to 20 ° C./humidity 25% RH is 0.45% or less. -The tensile modulus E (kgf / mm ² ) of the CD of the paper pretreated with -P-8118 and the thickness t (mm) of the paper,
Et3 ≧ 0.26
It is desirable to satisfy the following relationship.

  Further, it is desirable that the fiber orientation ratio between MD (paper machine traveling direction) and CD by the ultrasonic wave propagation method is 1.10 to 1.30.

  The above-described stabilization processing apparatus 100 is not limited to the apparatus shown in FIG. 2. For example, after the intermediate transfer member and the conductive rotating member are manufactured, the used mold is used as the intermediate transfer member and the conductive rotating member. The electrode may be used as it is. Furthermore, the intermediate transfer member may be subjected to a conductive process in the image forming apparatus.

  Further, in the case of an image forming apparatus with a built-in humidity monitor, it is possible to perform the stabilization processing operation of the intermediate transfer member when the humidity monitor senses a low humidity environment without using a special stabilization processing device. A method of stabilization is also conceivable.

  Next, it is preferable to use a polyimide resin in which a conductive agent is dispersed for the intermediate transfer member used in the image forming apparatus of the present embodiment and the conductive rotating member such as a charging roll and a transfer roll. As the conductive agent, conductive or semiconductive fine powder can be used, and is not particularly limited as long as a desired electric resistance can be stably obtained. For example, Ketchen Black, acetylene Examples thereof include carbon black such as black, metals such as aluminum and nickel, metal oxide compounds such as tin oxide, and potassium titanate. These conductive agents may be used alone or in combination, but it is preferable to use carbon black which is advantageous in terms of price. More preferably, good dispersion stability can be obtained, variation in resistance of the conductive rotating member can be reduced, electric field dependency is also reduced, and electric field concentration due to transfer voltage is less likely to occur over time. From the viewpoint of stability, it is preferable to use oxidized carbon black having a pH of 5 or less.

  Oxidized carbon black can be produced by oxidizing carbon black to impart a carboxyl group, a quinone group, a lactone group, a hydroxyl group or the like to the surface. This oxidation treatment includes an air oxidation method that reacts in contact with air in a high temperature atmosphere, a method that reacts with nitrogen oxides and ozone at room temperature, and air oxidation at a high temperature, followed by ozone at a low temperature. It can be carried out by an oxidation method or the like. Specifically, oxidized carbon black can be produced by a contact method. Examples of the contact method include a channel method and a gas black method. Oxidized carbon black can also be produced by a furnace black method using gas or oil as a raw material. If necessary, after these treatments, a liquid phase oxidation treatment with nitric acid or the like may be performed. Acidic carbon black can be produced by a contact method, but is usually produced by a closed furnace method in many cases. In the furnace method, only carbon black having a high pH and a low volatile content is usually produced, but carbon black having a desired pH can be produced by adjusting the pH by performing the above-described liquid phase acid treatment. Therefore, carbon black that has been adjusted to pH 5 or lower by subjecting the carbon black obtained by the furnace method to a post-process treatment may be used in this embodiment.

  The pH value of the oxidized carbon black may be pH 5.0 or less, preferably pH 4.5 or less, more preferably pH 4.0 or less. Oxidized carbon having a pH of 5.0 or lower has oxygen-containing functional groups such as carboxyl group, hydroxyl group, quinone group, and lactone group on the surface, so it has good dispersibility in the resin and reduces resistance variation of the semiconductive belt. In addition, since the electric field dependency is reduced, electric field concentration due to the transfer voltage is less likely to occur.

  The pH value of carbon black is determined by adjusting an aqueous suspension and measuring with a glass electrode. The pH of the acidic carbon black can be adjusted to a desired value depending on conditions such as the treatment temperature and treatment time in the oxidation treatment step.

  The oxidation-treated carbon black preferably contains 1% to 25%, preferably 2% to 20%, more preferably 3.5% to 15% of the volatile component. When the volatile content is less than 1%, the effect of oxygen-containing functional groups attached to the surface is reduced, and the dispersibility in the binder resin may be reduced. On the other hand, when the volatile content is higher than 25%, the molded product is decomposed when dispersed in the binder resin or obtained by increasing the amount of water adsorbed on the oxygen-containing functional group on the surface. Problems such as deterioration of the appearance of the product may occur. Therefore, by setting the volatile content within the above range, the dispersion in the binder resin can be improved. This volatile content can be determined from the ratio of organic volatile components (carboxyl group, hydroxyl group, quinone group, lactone group, etc.) that come out when carbon black is heated at 950 ° C. for 7 minutes.

  Two or more types of carbon black may be contained in the intermediate transfer member and the conductive rotating member used in the image forming apparatus of the present embodiment. The plurality of carbon blacks preferably have substantially different conductivity from each other. For example, those having different physical properties such as the degree of oxidation treatment, DBP oil absorption, specific surface area by BET utilizing nitrogen adsorption, and the like. It is preferable to use it. Thus, when adding two or more types of carbon blacks having different electrical conductivity, for example, after preferentially adding carbon black exhibiting high electrical conductivity, carbon black with low electrical conductivity is added to increase the surface resistivity. It is possible to adjust. Thus, even when two or more types of carbon black are contained, at least one of them can be sufficiently mixed and dispersed by using oxidized carbon black as one of them.

  Specific examples of the oxidized carbon black include “Printex 150T” (pH 4.5, volatile content 10.0%) and “Special Black 350” (pH 3.5, volatile content 2.2) manufactured by Degussa. %), “Special Black 100” (pH 3.3, volatile content 2.2%), “Special Black 250” (pH 3.1, volatile content 2.0%), “Special Black 5” (pH 3. 0, volatile content 15.0%), "Special Black 4" (pH 3.0, volatile content 14.0%), "Special Black 4A" (pH 3.0, volatile content 14.0%), " "Special Black 550" (pH 2.8, volatile content 2.5%), "Special Black 6" (pH 2.5, volatile content 18.0%), "Color Black FW200" (pH 2.5, volatile content 20) .0 ), “Color Black FW2” (pH 2.5, volatile content 16.5%), “Color Black FW2V” (pH 2.5, volatile content 16.5%), “MONARCH1000” (pH 2.5) manufactured by Cabot Corporation. , Volatile content 9.5%), Cabot "MONARCH1300" (pH2.5, volatile content 9.5%), Cabot "MONARCH1400" (pH2.5, volatile content 9.0%), the same "MOGUL" -L "(pH 2.5, volatile matter 5.0%)," REGAL400R "(pH 4.0, volatile matter 3.5%) and the like.

  Moreover, the car black to be used can also be refine | purified. Here, purification means removing impurities mixed in the manufacturing process, for example, residual oxidant, impurities such as processing agents and by-products, other inorganic impurities, and organic impurities. For example, impurities are removed by high-temperature heat treatment at about 500 ° C. to 1000 ° C. in an inert gas or vacuum, treatment with an organic solvent such as carbon disulfide or toluene, water slurry mixing, or mixing treatment in an organic acid aqueous solution. And so on. Any purification method may be used, and the purification method is not limited to the above method. However, the heat treatment of the powder is difficult to handle in the manufacturing process, and has a problem of using a lot of energy. Accordingly, the purification method is preferably organic solvent treatment or water-based treatment. In particular, a water-based treatment method is preferable from the viewpoint of safety. As water to be used, it is preferable to use ion-exchanged water, ultrapure water, distilled water, ultrafiltered water or the like in order to prevent contamination of impurities.

  Moreover, since the surface of carbon black is highly active and very easily adsorbs substances, it is necessary to purify carbon black immediately before use. Preferably 72 hours before, more preferably 48 hours before. If it exceeds 72 hours, impurities may be re-adsorbed on the surface of carbon black, and the purification effect will be reduced. Specifically, a method of separating carbon black after preparing and mixing a slurry in which carbon black and water are mixed as essential components is preferable. Further, from the viewpoint of improving the wettability of the carbon black surface, substances having a surface active action, for example, so-called surfactants and alcohols may be added. Moreover, although a water-soluble organic solvent may be added as needed, it is preferable that it does not remain after manufacture. Therefore, a solvent having a low boiling point and a surface activity is preferable. For example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, sec-butyl alcohol, tert-butyl alcohol, 2-methoxy alcohol, allyl alcohol and the like. Further, an inorganic acid can be added at an appropriate time.

  As a mixing method, it is necessary to solve carbon black aggregates to the primary particle size as much as possible. For this reason, it is preferable to treat the slurry with a general disperser or homogenizer. For example, colloid mill, flow jet mill, slasher mill, high speed disperser, ball mill, attritor, sand mill, sand grinder, ultra fine mill, Eiger motor mill, dyno mill, pearl mill, agitator mill, cobol mill, three roll mill, two roll mill , Extruder, kneader, microfluidizer, laboratory homogenizer, ultrasonic homogenizer, jet mill, and the like. These may be used alone or in combination. In order to prevent the mixing of inorganic impurities, it is preferable to use a dispersion method that does not use a dispersion medium, and a microfluidizer, an ultrasonic homogenizer, a jet mill, or the like is suitable.

  Examples of the separation method include a method of obtaining purified carbon black by centrifugation, filtration, and transfer to a water-insoluble organic solvent. Examples of the water-insoluble organic solvent include toluene, xylene, benzene, chloroform, hexane, heptane and the like. From the viewpoint of safety, separation by centrifugation or filtration is preferable.

  The carbon black after separation is desirably dried by heating in an inert gas, but a drying step is not necessarily required because high temperature treatment is performed in the production stage.

  The ratio of carbon black to water is preferably 5 wt% to 30 wt%, and more preferably 5 wt% to 20 wt%. If it is 5 wt% or less, the yield by purification is low, and high productivity cannot be obtained. On the other hand, if it exceeds 30 wt%, the slurry becomes highly viscous and mixing becomes difficult, resulting in a reduction in purification efficiency.

  Oxidized carbon black has better dispersibility in the resin composition due to the effect of oxygen-containing functional groups present on the surface as compared with general carbon black. Can be increased, which is preferable. This makes it possible to increase the amount of carbon black in the intermediate transfer member and the conductive rotating member, so that it is possible to suppress in-plane variations in the electrical resistance value of the intermediate transfer member and the conductive rotating member, etc. The effect of using oxidized carbon black can be maximized.

  In the intermediate transfer member and the conductive rotating member of the present embodiment, the oxidation treatment such as suppressing the in-plane variation of the surface resistivity of the semiconductive belt by containing 10 wt% to 30 wt% of the oxidation treated carbon black. The effect of carbon black is demonstrated. If the content of the oxidized carbon black is less than 10 wt%, the uniformity of the electrical resistance is lowered, and the in-plane unevenness of the surface resistivity and the electric field dependency are increased. On the other hand, if the content of the oxidized carbon black exceeds 30 wt%, it is difficult to obtain a desired resistance value, which is not preferable. Furthermore, by containing 18 wt% to 30 wt% of oxidized carbon black, the effect can be maximized, and the in-plane unevenness and electric field dependency of the surface resistivity can be remarkably improved.

  Next, a method for producing a polyamic acid solution in which carbon black is dispersed will be described below, but is not limited thereto. Prepare purified carbon black and disperse it in an organic polar solvent. As a dispersion method, a method of dispersing with a disperser or a homogenizer after preliminary stirring is preferable. As with the carbon black purification method, the mixing of fine media reduces the carbon black purification effect, so a media-free dispersion method that does not use media is preferred, especially with a jet mill that can uniformly disperse a high-viscosity solution. A dispersion method is preferred. A polyamic acid solution in which carbon black is dispersed is prepared by dissolving and polymerizing a diamine component and an acid dianhydride component in the obtained carbon black dispersion. The polyamic acid solution in which carbon black is dispersed is prepared by dissolving and polymerizing the diamine component and the acid anhydride component in the carbon black dispersion obtained previously. At this time, the monomer concentration (the concentration of the diamine component and the acid anhydride component in the solvent) can be set according to various conditions, but is preferably 5 wt% to 30 wt%. Moreover, it is preferable to set reaction temperature to 80 degrees C or less, More preferably, it is 5 to 50 degreeC. The reaction time is preferably 5 hours to 10 hours.

  Since the polyamic acid solution in which carbon black is dispersed is a high-viscosity solution, the air bubbles mixed at the time of production do not spontaneously escape, and defects such as belt protrusions, dents and holes due to the air bubbles are generated by application. Therefore, it is desirable to perform defoaming treatment, and it is preferable to perform defoaming as much as possible just before coating.

  Next, a method for forming a seamless belt used as an intermediate transfer member of the image forming apparatus of this embodiment will be described. In this case, for example, an appropriate method such as a method in which the polyamic acid solution is immersed in the outer peripheral surface of the cylindrical mold, a method in which the polyamic acid solution is applied to the inner peripheral surface, a method in which centrifugal force is used, or a method in which the casting mold is filled is used. Conventionally, such as a method of expanding into a ring shape by the method, forming the expanded layer into a bell-shaped shape, heat-treating the molded product to convert the polyamic acid into an imide, and then removing from the mold It can be appropriately carried out by known methods (for example, see JP-A-61-95361, JP-A-64-22514, JP-A-3-180309, etc.).

  As a method of converting to imide, a method of treating at a high temperature of 200 ° C. or higher is common. Sufficient imide conversion cannot be obtained at 200 ° C. or lower. On the other hand, high-temperature processing is advantageous for imide conversion, and stable characteristics can be obtained. However, since high thermal energy is used, the thermal efficiency is low and the cost is high, so the heat treatment temperature is considered in consideration of the characteristics and productivity of the intermediate transfer member. It is necessary to decide.

The surface resistivity of the transfer surface of the intermediate transfer member is preferably 1 × 10 ¹⁰ Ω / □ to 1 × 10 ¹⁴ Ω / □, and is 1 × 10 ¹¹ Ω / □ to 1 × 10 ¹³ Ω / □. It is more preferable. When the surface resistivity is higher than 1 × 10 ¹⁴ Ω / □, peeling discharge is likely to occur at the post nip where the toner image carrier and the intermediate transfer member are peeled off, and the portion where the discharge has occurred is blanked out. Image quality defects may occur.

On the other hand, when the surface resistivity of the transfer surface of the intermediate transfer member is less than 1 × 10 ¹⁰ Ω / □, the electric field strength at the pre-nip portion becomes strong, and gap discharge at the pre-nip portion is likely to occur. The graininess of the may deteriorate. Therefore, by setting the surface resistivity within the above range, it is possible to prevent white spots due to peeling discharge that occurs when the surface resistivity is high and image quality deterioration that occurs when the surface resistivity is low.

  The surface resistivity of the transfer surface of the intermediate transfer member and the conductive rotating member of the present embodiment is determined according to JIS-K-6991 using a circular electrode (for example, “HR Probe” of Hiresta IP manufactured by Mitsubishi Oil Chemical Co., Ltd.). Can be measured. A method for measuring the surface resistivity will be described with reference to the drawings.

  FIG. 3 is a schematic plan view (a) and a schematic cross-sectional view (b) showing an example of a circular electrode for measuring the surface resistivity of the intermediate transfer member and the conductive rotating member.

  As shown in FIG. 3, the circular electrode 30 includes a first voltage application electrode 31 and a plate-like insulator 32. The first voltage application electrode 31 has a cylindrical electrode portion 33 and a cylindrical ring electrode portion having an inner diameter larger than the outer diameter of the cylindrical electrode portion 33 and surrounding the cylindrical electrode portion 33 at a constant interval. 34.

  An intermediate transfer member and a conductive rotating member, for example, an intermediate transfer member 35 are sandwiched between the cylindrical electrode portion 33 and the ring-shaped electrode portion 34 of the first voltage applying electrode 31 and the plate-like insulator 32, and the first voltage is applied. The current I (A) that flows when the voltage V (V) is applied between the cylindrical electrode portion 33 and the ring-shaped electrode portion 34 in the application electrode 31 is measured, and the intermediate transfer member 35 is expressed by the following equation (3). The surface resistivity ρs (Ω / □) of the transfer surface can be calculated. Here, in the following formula (3), d (mm) indicates the outer diameter of the cylindrical electrode portion 33, and D (mm) indicates the inner diameter of the ring-shaped electrode portion 34.

ρs = π × (D + d) / (D−d) × (V / I) (3)
The intermediate transfer member and the conductive rotating member used in the image forming apparatus of this embodiment preferably have a volume resistivity of 1 × 10 ⁸ Ωcm to 1 × 10 ¹³ Ωcm, and 1 × 10 ⁹ Ωcm to 1 × 10. More preferably, it is ¹² Ωcm. When the volume resistivity is less than 1 × 10 ⁸ Ωcm, the electrostatic charge that holds the charge of the unfixed toner image transferred from the toner image carrier to the intermediate transfer member and the conductive rotating member, for example, the intermediate transfer member. Because the electrostatic force is difficult to work, toner is scattered around the image (blur phenomenon) due to the electrostatic repulsion between the toners and the force of the fringe electric field near the image edge, resulting in the formation of a noisy image. May be. On the other hand, when the volume resistivity of the intermediate transfer member and the conductive rotating member is higher than 1 × 10 ¹³ Ωcm, the charge holding power is large. A static elimination mechanism may be required for charging. Therefore, by setting the volume resistivity of the intermediate transfer member and the conductive rotating member within the above range, it is possible to solve the problem of toner scattering and the need for a static elimination mechanism.

  The volume resistivity of the intermediate transfer member and the conductive rotating member of this embodiment is the same as in the case of measurement of the surface resistivity. The circular electrode shown in FIG. ) And can be measured according to JIS-K-6991.

  In this case, for example, the intermediate transfer body 35 is sandwiched between the cylindrical electrode portion 33 and the ring-shaped electrode portion 34 of the first voltage application electrode 31 and the second voltage application electrode 32, and the first voltage application electrode 31. The current I (A) flowing when the voltage V (V) is applied between the cylindrical electrode portion 33 and the second voltage applying electrode 32 is measured, and the volume of the intermediate transfer body 35 is calculated by the following equation (4). The resistivity ρv (Ωcm) can be calculated. Here, in the following formula (4), t represents the thickness of the semiconductive belt T, and d represents the radius of the electrode.

ρv = πd ² / 4t × (V / I) (4)

  Next, examples of the method for treating an intermediate transfer member of the present invention will be described, but the present invention is not limited to these examples.

Carbon black (SPECIAL BLACK 4, manufactured by Degussa) was charged into a polyamic acid NMP solution composed of biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA), and dispersion treatment was performed with a Jetmill disperser. ^{(200 N / mm 2, 5pass} ). The produced carbon black-dispersed polyamic acid solution was vacuum degassed to produce a final coating solution.

  Next, the obtained polyamic acid solution is applied to the inner surface of the cylindrical mold through a dispenser to a thickness of 0.5 mm, and rotated at 1500 rpm for 15 minutes to form a spread layer having a uniform thickness. While rotating, hot air of 60 ° C. was blown from the outside of the mold for 30 minutes, and then heated at 150 ° C. for 60 minutes to remove NMP and make it semi-cured, followed by demolding. Next, the demolded belt was placed on an iron core, and the temperature was raised to a firing temperature of 250 ° C. to convert the imide, thereby obtaining a desired polyimide belt. The belt thickness was about 80 μm.

  The polyimide belt thus manufactured, that is, the intermediate transfer member 21 is set on the support roll 22 of the stabilization processing device 20 shown in FIG. 2, and power is supplied from the roll 22 to the intermediate transfer member 21. P grounding paper manufactured by Fuji Xerox Co., Ltd. was wound around the grounding roll 23 facing the support roll 22, and stabilized by rotating it the following number of times while applying the following current value. The initial surface resistance value before the stabilization treatment and the conductive width after the stabilization treatment are shown in Table 1 together with the conditions of Examples 1 to 5.

The treatment environment was 10 ° C. and 15% (absolute humidity 1.36 g / m ³ ).

  Next, the stabilization process under the conditions shown in Table 2 is shown as Comparative Example 1, and the case where the stabilization process is not performed is shown as Comparative Example 2. The initial surface resistance value and the conductive width are also shown. The processing environment is the same as in Examples 1-5.

  The surface resistivity of each intermediate transfer member, the fluctuation width of the surface resistivity of the paper running portion, and the copy after the transfer is repeated 10,000 times using the intermediate transfer members of Examples 1 to 5 and Comparative Examples 1 and 2 above. The results of evaluating the image quality are shown in Table 3. The environment is the same as in Examples 1-5.

  In addition, the surface resistivity is the circular electrode shown in FIG. 3 (HR probe of Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd .: the outer diameter of the cylindrical electrode C is 16 mm, the inner diameter of the ring-shaped electrode portion 34 is 30 mm, and the outer diameter is 40 mm), a voltage of 100 V was applied in an environment of 22 ° C. and 55% RH, and a current value after 10 seconds was obtained and calculated.

  The fluctuation range of the surface resistivity is obtained from the surface resistivity of the sheet running portion of the intermediate transfer member after continuous transfer is repeated 10,000 times while applying an electric field of 2.6 KV in an environment of 10 ° C. and 15% RH. It was. As the measurement environment, the fluctuation of the surface resistivity of the paper running part was measured.

  Incidentally, the copy image quality was evaluated by the following evaluation criteria by visually judging the copy image quality after 10,000 continuous transfer tests.

G1: Good G2: Normal G3: Bad G4: Very bad

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention. It is a figure which shows the basic composition of the stabilization processing apparatus of an intermediate transfer body and an electroconductive rotation member. It is the schematic plan view (a) and schematic sectional drawing (b) which show an example of the circular electrode for a surface resistivity measurement of an intermediate transfer body and an electroconductive rotation member. FIG. 5 is a schematic diagram illustrating resistance reduction in a secondary transfer portion of an intermediate transfer member. FIG. 6 is a diagram illustrating a state in which a sheet running portion of an intermediate transfer member has been deteriorated due to a decrease in resistance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Fixing roll 3, 4 Support roll 5 Secondary transfer roll 6 Recording medium 7 Paper tray 8 Laser generator 9 Image carrier 10 Primary transfer roll 11 Drive roll 12 Belt cleaner 13 Charging roll 14 Photoconductor cleaner 15 Development Device 16 Intermediate transfer body 20 Stabilization processing device 21 Intermediate transfer belt 22 Support roll 23 Ground roll 24 Plain paper 25 Power supply 30 Circular electrode 31 First voltage application electrode 32 Plate insulator 33 Columnar electrode section 34 Ring electrode section 100 Stabilization processing apparatus 101 Intermediate transfer belt 102 Support roll 103 Transfer roll 104 Plain paper 105 Bias power supply 200 Intermediate transfer belt 201 Paper running section 202 Non-paper running section

Claims (6)

By an image forming cycle in which a toner image is carried on a toner image carrier carrying a toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface and finally fixed on a recording medium. In an image forming apparatus for forming an image composed of a fixed toner image on a recording medium,
An intermediate transfer member having the transfer surface that circulates in a state where the surface is in contact with the toner image carrier; and
A bias applying unit that applies a predetermined bias to the intermediate transfer member when the image forming cycle is executed,
An image forming apparatus, wherein the intermediate transfer member has been subjected to surface conductivity treatment by electric field stress. A toner image is carried on a toner image carrier that carries a toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface, and finally fixed on a recording medium. In the intermediate transfer body having the transfer surface, which is provided in an image forming apparatus for forming an image composed of a fixed toner image thereon and circulates and moves in a state where the surface is in contact with the toner image carrier.
An intermediate transfer member, wherein the intermediate transfer member has been subjected to surface conductivity treatment by electric field stress. A toner image is carried on a toner image carrier that carries a toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface, and finally fixed on a recording medium. In the processing method of the intermediate transfer member having the transfer surface, which is provided in an image forming apparatus for forming an image composed of a fixed toner image thereon and circulates in a state where the surface is in contact with the toner image carrier.
A contact step of bringing the surface of the intermediate transfer member into contact with a high resistance member having a higher resistance than the intermediate transfer member;
A peeling step of peeling both in a state where an electric field is applied between the surface of the intermediate transfer member contacted in the contact step and the high resistance body,
An intermediate transfer member processing method, wherein the contact step and the peeling step are repeatedly executed. By an image forming cycle in which a toner image is carried on a toner image carrier carrying a toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface and finally fixed on a recording medium. In an image forming apparatus for forming an image composed of a fixed toner image on a recording medium,
A conductive rotating member that rotates while the surface is in contact with the toner image carrier;
A bias applying unit that applies a predetermined bias to the conductive rotating member when the image forming cycle is executed,
The image forming apparatus according to claim 1, wherein the conductive rotating member is subjected to a conductive treatment by electric field stress. A toner image is carried on a toner image carrier that carries a toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface, and finally fixed on a recording medium. In a conductive rotating member that is disposed in an image forming apparatus that forms an image composed of a fixed toner image on the surface and rotates with the surface in contact with the toner image carrier,
The conductive rotating member, wherein the conductive rotating member is subjected to a conductive treatment by electric field stress. A toner image is carried on a toner image carrier that carries a toner image, the toner image carried on the toner image carrier is transferred to a predetermined transfer surface, and finally fixed on a recording medium. In a processing method of a conductive rotating member that is disposed in an image forming apparatus that forms an image composed of a fixed toner image thereon and rotates with the surface in contact with the toner image carrier,
A contact step of bringing the conductive rotating member into contact with a high resistance body;
A peeling step of peeling both of the conductive rotating member brought into contact in the contact step and the high resistance body in a state where an electric field is applied,
A method for treating a conductive rotating member, wherein the contacting step and the peeling step are repeatedly performed.

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