JP2005099183A - Semiconductive belt, intermediate transfer body, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductive belt which is free of the degradation in belt resistance due to a transfer voltage, is improved in the uniformity of electric resistance, is reduced in the change of electric resistance due to an environmental change, can be improved in the amount of a dimensional change with time during use of the belt, and in addition, with which high image quality can be obtained, and an intermediate transfer body and further, to provide an image forming apparatus with which the high quality transfer image can be stably obtained. <P>SOLUTION: The semiconductive belt to be used in the electrophotographic image forming apparatus contains a polyimide resin as a resin component and contains flaky composite particle powder coated with a surface layer developing conductivity by electron conduction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic method such as a copying machine or a printer, and in particular, after a toner image formed on a latent latent image carrier is once transferred to an intermediate transfer member, this is recorded on a recording medium such as paper The present invention relates to a semiconductive belt applied to an intermediate transfer belt and a paper conveying belt provided in an image forming apparatus or the like that is transferred to the image forming apparatus and the like, an intermediate transfer member using the same, and an image forming apparatus.

  In an image forming apparatus using an electrophotographic method, a uniform charge is formed on a latent latent image carrier made of a photoconductive photoconductor made of an inorganic or organic material, and electrostatic charge is generated by a laser beam or the like that modulates an image signal. After forming the latent image, the electrostatic latent image is developed with charged toner to obtain a visualized toner image. Then, the toner image is electrostatically transferred to a transfer material such as a recording medium through an intermediate transfer member or a desired reproduced image is obtained. In particular, an image forming apparatus employing a system (intermediate transfer system) in which the toner image formed on the latent latent image carrier is primarily transferred to an intermediate transfer body, and the toner image on the intermediate transfer body is secondarily transferred to a recording medium. Is disclosed (for example, see Patent Document 1).

  Examples of materials used in the image forming apparatus employing the intermediate transfer body method include polycarbonate resin, PVDF (polyvinylidene fluoride), polyalkylene phthalate, PC (polycarbonate) / PAT (polyalkylene terephthalate) blend material, and ETFE (polyethylene terephthalate). Ethylene tetrafluoroethylene copolymer) / PC, ETFE / PAT, PC / PAT blend material, etc., semi-conductive (hereinafter referred to as "semi-conductive" A proposal has been made to use an endless belt having a value in the following semiconductive region (see, for example, Patent Documents 2 to 7). Further, as a belt material used in an image forming apparatus employing an intermediate transfer body method, an elastic belt with a reinforcing material formed by laminating a woven fabric such as polyester and an elastic member such as NBR (nitrile butadiene rubber) has been proposed. (For example, see Patent Documents 8 and 9).

  In addition, as a material used for the paper conveying belt, a conductive agent is dispersed in an elastic member such as the above-mentioned ETFE (ethylene tetrafluoroethylene copolymer) resin material, CR (chloropyrene), EPDM (ethylene propylene diene polymer), or the like. A proposal has been made to use a semiconductive endless belt.

However, it is very difficult to control the resistance value of the resin material in the semiconductive region (about 10 ⁵ to 10 ¹¹ Ωcm), and the desired resistance can be obtained by adding normal conductive carbon black to a normal resin material. The value can hardly be obtained stably. For this reason, since it is necessary to measure and select the resistance values of all the semiconductive endless belts, the cost is high.

  The reason why it is difficult to control the resistance value is that when carbon black is added to a polymer such as a resin material, the conductivity is small while adding a small amount of carbon black. This is because a conductor circuit is formed, the conductivity is rapidly improved, and a medium resistance value cannot be obtained (for example, see Non-Patent Document 1).

  In the case of the carbon black-dispersed polycarbonate and the carbon black-dispersed ethylene tetrafluoroethylene copolymer, after continuously transferring 3000 sheets or more of paper shorter than the width of the intermediate transfer body such as a postcard, halftone (magenta When the image of 30%) was transferred, there was a problem that the paper running portion slipped out. This white-out image quality defect was particularly remarkable in a low-temperature and low-humidity environment of 10 ° C. and 15% RH. The paper running part slips off because the surface resistivity of the paper running part of the intermediate transfer body is lower than the peripheral part due to the peeling discharge between the intermediate transfer body and the paper when the paper is peeled off at the secondary transfer part. This is because the transfer efficiency is lower than the peripheral part.

  The electric field dependence of the surface resistivity of the carbon black-dispersed polycarbonate and the carbon black-dispersed ethylene tetrafluoroethylene copolymer is at a level of 0.8 to 1.5 (log Ω / □), and the electric field is concentrated by the transfer voltage. As a result, it is considered that the resin component around the highly conductive portion is deteriorated and the surface resistivity is lowered.

  The electric field dependence of the surface resistivity is large because, as described above, it is difficult to uniformly disperse carbon black in the resin component constituting the intermediate transfer member, so that carbon black is unevenly dispersed in the resin. Therefore, locally, there is a portion with high conductivity, and it is considered that the electric field concentrates there.

  In order to impart conductivity to the material constituting the intermediate transfer member, there are a method of imparting a conductive agent imparting electron conductivity such as carbon black and a method of imparting a conductive agent imparting ionic conductivity to the composition material. is there. When a conductive agent that imparts ionic conductivity is applied, the change in the electrical resistance value in the surface of the intermediate transfer member is as extremely small as 0.5 digits or less, and there is a portion where the local conductivity is large. There are few problems that the surface resistance is lowered due to the concentration of the electric field. On the other hand, the electrical resistance value fluctuates greatly with changes in temperature and humidity. For example, a high temperature and high humidity environment (H / H environment) of 30 ° C. and 85% RH and a low temperature and low humidity environment (L / (L environment) has a problem that the difference in electrical resistance value is 1.5 to 4 digits (log Ω).

  Furthermore, in general, the conductive agent imparting ionic conductivity needs to increase the amount of the conductive agent in order to obtain a predetermined electric resistance value at low temperature and low humidity. A new problem arises that the ink oozes out from the surface and shifts (bleeds out) to the surface of the latent latent image bearing member, thereby easily causing image deterioration, contamination, sensitive material erosion, and the like.

  As the above-mentioned countermeasure, a proposal has been made to use a laminate of a material obtained by dispersing a conductive agent that imparts ionic conductivity and a material obtained by dispersing a conductive agent that imparts electronic conductivity (for example, Patent Documents). 10). However, in the case of such a structure of two or more layers, the higher resistance layer dominates the belt resistance, so that the behavior of the material of the high resistance layer is exhibited. For example, if the layer of the material in which the conductive agent of the electron conduction type is dispersed has a higher resistance than the layer of the material in which the conductive agent of the ionic conductivity type is dispersed, the resistance variation is large. There are problems such as large dependency.

  The above-mentioned electric resistance value of the intermediate transfer member is controlled within a predetermined range in order to obtain high-quality transfer image quality, and there is little in-plane variation (maximum resistance value and minimum value) of the intermediate transfer member. In addition, it is required that the electrical resistance value does not change greatly even when the use environment conditions change, and that high quality can be stably obtained. For example, practically, the in-plane variation of the electrical resistance value of the intermediate transfer member is within 1 (logΩ / □), and the low temperature and low humidity environment (L / L environment) of 10 ° C. and 15% RH and 30 ° C. It is required that the change in electrical resistance value with a high-temperature, high-humidity environment (H / H environment) of 85% RH is within 1.5.

  In the prior art, the belt is driven by using two or more metal rolls, a roll formed by coating a resin layer on the metal surface, a rubber roll, and the like. Conventional full-color copiers and printers targeting some corporate users at a high price are becoming a target for a wider range of users, including small and medium offices and general households. Full-color copiers and printers for these users need to be smaller, cheaper, and faster than ever.

  For this reason, it has become necessary to reduce the cost by making the belt drive system a simple configuration. In order to reduce the size of the main body and make the belt drive system simple, it is difficult to obtain a stable belt drive speed when the belt circumference changes significantly and the belt tension changes. In the device use environment (hereinafter referred to as “M / C use environment”), it is required that the belt circumference does not change within a certain range.

  Further, the temperature and humidity of the environment in which the M / C is used change, and the belt circumference changes beyond a certain range, so that the belt tension deviates from the range in which the belt speed can be stably controlled. . For example, when the belt circumference becomes long, the belt tension becomes weak, the grip force with the roll that drives the belt becomes weak, and the belt speed fluctuates due to slipping, so that multi-color toner is superimposed. There may be a problem of displacement.

  In the case of the elastic belt with the reinforcing material, an attempt has been made to reduce the elongation over time due to the tension at the time of driving the belt by using a woven fabric such as polyester as a reinforcing material, but the effect is insufficient. . In the case of a belt, a tension of 5 kgf is necessary to maintain a stable drive, and this belt tension causes an increase in the belt circumference over time. There is a problem that requires replacement.

  On the other hand, as a semiconductive belt that can be used for an intermediate transfer belt, a paper conveying belt, etc., an intermediate transfer belt is proposed in which a conductive filler is dispersed in a polyimide resin having excellent mechanical properties and heat resistance (for example, (See Patent Document 11).

  However, the semiconducting belts made of polyimide resin proposed so far have a poor balance between flexibility and rigidity, and although the intermediate transfer belt and the paper transport belt are satisfactory in characteristics. There wasn't. Furthermore, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, p-phenylenediamine, and polyamic acid (U varnish-S), which is a polymer, are used as raw materials for the polyimide resin, and a conductive filler is added thereto. A dispersed belt is disclosed. This type of intermediate transfer belt has a surface microhardness of 40 or more, excellent mechanical properties, no belt deformation due to stress during driving, and high-quality transfer image quality without color shift can be stably obtained.

  On the other hand, since the polyimide resin material has excellent mechanical characteristics in the transfer portion, the recording paper is pressed against the recording medium using a bias roller and an electric field is applied to electrostatically transfer the toner image. Since the deformation due to the pressing force by the bias roller in the primary transfer portion is small, the pressing force by the bias roller is concentrated. As a result, the toner aggregates and the charge density increases, causing discharge inside the toner layer and causing image quality defects such as line image loss (holographic characters) due to changes in toner polarity. (For example, refer to Patent Document 11).

Further, as a two-layer polyimide resin belt mainly composed of a polyimide resin, the surface layer is a polymer of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine. A polyimide-based two-layer belt has been proposed, but the polyimide resin material of the surface layer has a surface microhardness of 40 or more, and a problem of generating an image quality defect in which a line image is missing (holocharacter). (For example, refer to Patent Document 12).
JP-A-62-206567 Japanese Patent Laid-Open No. 06-095521 Japanese Patent Laid-Open No. 5-200904 JP-A-6-228335 Japanese Patent Laid-Open No. 6-149081 Japanese Patent Laid-Open No. 6-149083 Japanese Patent Laid-Open No. 6-149079 Japanese Patent Laid-Open No. 9-305038 Japanese Patent Laid-Open No. 10-240020 JP-A-8-110711 Japanese Patent Laid-Open No. 10-63115 JP 2002-156835 A Polymer processing, 43, 4, 1977, Sumita

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the object of the present invention is that there is no reduction in belt resistance due to transfer voltage, the uniformity of electrical resistance is improved, the change in electrical resistance due to environmental changes is small, and the dimensional change over time when the belt is used is improved. In addition to the above, it is an object to provide a semiconductive belt capable of obtaining high image quality and an intermediate transfer body comprising the same, and to provide an image forming apparatus capable of stably obtaining high-quality transfer image quality.

The above problem is solved by the following means. That is, the present invention
<1> A semiconductive belt used in an electrophotographic image forming apparatus,
A semiconductive belt comprising a flaky composite particle powder containing a polyimide resin as a resin component and coated with a surface layer that exhibits conductivity by electronic conduction.

<2> The semiconductive belt according to <1>, wherein the flaky composite particle powder is obtained by coating a surface layer containing carbon black on a surface of an inorganic oxide particle powder.

<3> The flaky composite particle powder is characterized in that a surface layer containing carbon black is coated on the surface of a hydrated aluminum potassium silicate particle powder having an aspect ratio (diameter / thickness) of 2 to 500. <1> or <2> is the semiconductive belt.

<4> The flaky composite particle powder is obtained by coating the surface of a hydrated aluminum potassium silicate particle powder with a surface layer containing an organosilane compound or polysiloxane generated from alkoxysilane, and carbon black is formed on the surface layer. The semiconductive belt according to any one of <1> to <3>, which is attached and has an average diameter of 0.001 mm or more and less than 5 mm.

<5> The content of the flaky composite particle powder is in the range of 5 to 50 parts by mass per 100 parts by mass of the resin component, and the half according to any one of <1> to <4> It is a conductive belt.

<6> The semiconductive belt according to any one of <2> to <5>, wherein the carbon black is acidic carbon black having a pH of 5 or less.

<7> A polymer in which the polyimide resin is formed by imide bonding a tetracarboxylic dianhydride having a wholly aromatic skeleton and a diamine component using 4,4′-diaminophenyl ether as a main component. It is a semiconductive belt according to any one of <1> to <6>.

<8> An intermediate transfer member comprising the semiconductive belt according to any one of <1> to <7>.

<9> An image forming apparatus using the semiconductive belt according to any one of <1> to <7> as an intermediate transfer belt.

<10> An image forming apparatus using the semiconductive belt according to any one of <1> to <7> as a paper transport belt.

<11> An image forming apparatus including at least a latent image carrier and an intermediate transfer belt and / or a paper transport belt, wherein the latent image carrier is plural. <9> or <10> The image forming apparatus described in the above.

<12> An image forming apparatus having means for developing at least the electrostatic latent image formed on the surface of the latent image carrier as a toner image with a developer containing toner,
Any one of <9> to <11>, wherein the toner is a spherical toner having a shape factor (ML ² / A) defined by the following formula (1) in a range of 100 to 140. This is an image forming apparatus.
(ML ² / A) = (absolute maximum length of toner particles) ² / (projected area of toner particles) × (π / 4) × 100 (1)

  Thus, according to the present invention, the uniformity of electrical resistance is improved when a conductive agent imparting electronic conductivity is used, the change in electrical resistance due to the environment is small, and the amount of dimensional change over time of the belt. Can be provided, and a semiconductive belt capable of obtaining higher image quality can be provided, and an image forming apparatus capable of stably obtaining high-quality transfer image quality can be provided.

Hereinafter, the present invention will be described in detail.
<Semiconductive belt, intermediate transfer member>
The semiconductive belt according to the present invention (hereinafter sometimes simply referred to as “belt”) is used in an electrophotographic image forming apparatus, includes a polyimide resin composition as a resin component, and exhibits conductivity by electronic conduction. The flaky (plate-like) composite particle powder coated with the surface layer is uniformly dispersed. As a result, a desired resistance value with little change in electrical resistance due to environmental changes can be stably obtained, and there is no reduction in belt resistance due to transfer voltage, and the uniformity of electrical resistance can be improved. Furthermore, the addition of flaky composite particle powder has the effect of increasing the rigidity (Young's modulus) of the resin composition and reducing the thermal expansion coefficient, and reducing the amount of change in the circumferential length of the belt over time. Can do. In addition, it is possible to stably provide a high-quality image without occurrence of the hollow character or the like.

The flaky composite particle powder in the present invention can impart uniform conductivity to the belt by being dispersed in the resin component because the surface layer has conductivity. Since it plays a role as a reinforcing agent, it has an effect of imparting rigidity to the belt. In this case, since the flaky composite particle powder is plate-shaped, it is oriented and dispersed so that the flat surface of the particles is substantially parallel to the belt surface. Therefore, while the strength in the direction parallel to the belt surface is reinforced, the surface of the belt can be made relatively soft, and a belt having both rigidity and surface flexibility can be obtained.
For this reason, the deformation amount when the belt is used can be reduced, and for example, even if the recording paper is pressed against the semiconductive belt which is an intermediate transfer belt in the transfer portion, aggregation of the toner can be suppressed and the holocharacter can be suppressed. Can be reduced.

  The use of the semiconductive belt of the present invention is not particularly limited, but it is preferably used as an intermediate transfer member. In addition, in an image forming apparatus, not only an intermediate transfer belt as an intermediate transfer member, but also paper conveyance It is preferably used also as a belt.

-Flake composite particle powder-
The flaky composite particle powder in the present invention refers to a plate-like particle whose surface is coated with a component different from the mother particle.
In the flaky composite particle powder, an electrically conductive conductive agent is used as the material for the surface layer having conductivity because the developed conductivity is desired to be less affected by the environment.

  The electron conductivity is a metal or alloy such as carbon black, graphite, aluminum, nickel, copper alloy, tin oxide, zinc oxide, potassium titanate, tin oxide-indium oxide or tin oxide-antimony oxide composite oxidation. Examples thereof include metal oxides. Carbon blacks such as furnace black, ketjen black, and channel black are preferably used as a conductive agent used for imparting conductivity that is generally used. More specifically, granular acetylene black manufactured by Electrochemical Co., Ltd., HS-500 manufactured by Asahi Carbon Co., Ltd., Asahi Thermal FT, Asahi Thermal MT, Ketjen Black manufactured by Lion Azo Co., and Cabot Co., Ltd. Vulcan XC-72 made by Cabot, “REGAL 400R”, “MONARCH 1300” from Cabot, “Color Black FW200” from Degussa, “SPECIAL BLACK 4”, “PRINTEX 150T”, “PRINTEX 140T”, “PRINTEX U”, etc. It is done. These may be used alone or in combination of two or more.

  As the conductive agent in the present invention, good dispersibility and dispersion stability in the resin composition (resin component) can be obtained, resistance variation of the semiconductive belt can be reduced, and electric field dependency is also small. Further, acidic carbon black having a pH of 5 or less is preferably used from the viewpoint of improving the stability of electric resistance over time without causing electric field concentration due to a transfer voltage.

  The acidic carbon black having a pH of 5 or less can be produced by oxidizing the carbon black to give a carboxyl group, a quinone group, a lactone group, a hydroxyl group, or the like to the surface. This oxidation treatment is an air oxidation method in which contact is made with air in a high-temperature atmosphere to react, a method of reacting with nitrogen oxides or ozone at room temperature, and air oxidation at high temperature, followed by ozone oxidation at a low temperature. It can be performed by a method or the like. Specifically, acidic carbon black having a pH of 5 or less can be produced by a contact method. Examples of the contact method include a channel method and a gas black method.

  Acidic carbon black can also be produced by a furnace black method using gas or oil as a raw material. Further, if necessary, after performing these treatments, a liquid phase oxidation treatment with nitric acid or the like may be performed. Although acidic carbon black can be produced by the contact method as described above, it is usually produced by a closed furnace method. In this furnace method, only carbon black having a high pH and a low volatile content is usually produced, but the pH can be adjusted by subjecting it to the above-mentioned liquid phase oxidation treatment. For this reason, in the present invention, carbon black obtained by furnace method production and adjusted to have a pH of 5 or less by post-treatment is regarded as being included in acidic carbon black having a pH of 5 or less.

The pH value of the acidic carbon black in the present invention is preferably pH 5.0 or less, more preferably pH 4.5 or less, and further preferably pH 4.0 or less. Acidic carbon having a pH of 5.0 or less has an oxygen-containing functional group such as a carboxyl group, a hydroxyl group, a quinone group, and a lactone group on the surface, so that the dispersibility in the resin is good and good dispersion stability is obtained. The resistance variation of the semiconductive belt can be reduced, and the electric field dependency is also reduced, so that electric field concentration due to the transfer voltage hardly occurs.
The lower limit of the pH value of the acidic carbon black is about 2.

  The pH of the carbon black is determined by adjusting an aqueous suspension of carbon black and measuring it with a glass electrode. Further, the pH of the carbon black can be adjusted by conditions such as the treatment temperature and treatment time in the oxidation treatment step.

  The acidic carbon black having a pH of 5.0 or less preferably has a volatile component content in the range of 1 to 25% by mass, more preferably 3 to 20% by mass, and 3.5 to 15% by mass. More preferably, it is contained in the range of%. When the content of the volatile component is less than 1% by mass, the effect of the oxygen-containing functional group attached to the surface is lost, and the dispersibility to the resin component may be reduced. On the other hand, when the content of the volatile component is higher than 25% by mass, it may be decomposed when dispersed in the resin composition, or the amount of water adsorbed on the oxygen-containing functional group on the surface may increase. The appearance of the belt surface in the present invention may deteriorate.

  On the other hand, the dispersion | distribution in the said resin composition can be made more favorable by making content of the said volatile component into the range of 1-25 mass%. The content of the volatile component can be obtained 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. .

  Specific examples of acidic carbon black having a pH of 5.0 or less include “Printex 150T” (pH 4.5, volatile content 10.0% by mass) and “Special Black 350” (pH 3.5, volatile) manufactured by Degussa. 2.2% by mass), “Special Black 100” (pH 3.3, volatile content 2.2% by mass), “Special Black 250” (pH 3.1, volatile content 2.0% by mass), “ Special Black 5 ”(pH 3.0, volatile content 15.0% by mass),“ Special Black 4 ”(pH 3.0, volatile content 14.0% by mass),“ Special Black 4A ”(pH 3.0, volatile) 14.0% by mass), “Special Black 550” (pH 2.8, volatile content 2.5% by mass), “Special Black 6” (pH 2.5, volatile content 18.0% by mass), “ Carabu FW200 "(pH 2.5, volatile content 20.0% by mass)," Color Black FW2 "(pH 2.5, volatile content 16.5% by mass)," Color Black FW2V "(pH 2.5, volatile) 16.5% by mass), “MONARCH1000” manufactured by Cabot (pH 2.5, volatile content 9.5% by mass), “MONARCH 1300” manufactured by Cabot (pH 2.5, volatile content 9.5% by mass), Cabot Corporation “MONARCH1400” (pH 2.5, volatile matter 9.0% by mass), “MOGUL-L” (pH 2.5, volatile matter 5.0% by mass), “REGAL400R” (pH 4.0, volatile matter 3) 0.5 mass%) and the like.

  The acidic carbon black having a pH of 5.0 or less is more conductive than the general carbon black because it has better dispersibility in the resin composition due to the effect of the oxygen-containing functional group present on the surface as described above. It is preferable to increase the addition amount as a powder. Thereby, since the amount of conductive particles in the semiconductive belt increases, the effect of using acidic carbon black, such as being able to suppress the in-plane variation of the electrical resistance value, can be maximized. it can.

  Hereinafter, an embodiment in which carbon black is used as the electron conductive conductive agent will be described, but it goes without saying that the present invention can be similarly applied even when a conductive agent other than carbon black is used.

  As a suitable form of the flaky composite particle powder in the present invention, an inorganic oxide particle powder surface having an aspect ratio (diameter / thickness) in the range of 2 to 500 and an average diameter of 0.001 mm or more and less than 5 mm is used as a carbon. Examples thereof include composite particle powder formed by coating with a surface layer containing black. Further, particularly preferably as the flaky composite particle powder, the surface of the hydrated aluminum potassium silicate particle powder as the inorganic oxide particle powder is coated with a surface layer containing an organosilane compound or polysiloxane generated from alkoxysilane, and It is a flaky composite particle powder having an average diameter of 0.001 mm or more and less than 5 mm with carbon black attached to the surface layer.

  As the inorganic oxide particle powder in the present invention, specifically, mascovite (muscovite), flocovite gold (mica), biotite (biotite), fluorine represented by the hydrated potassium aluminum silicate formula Preferable examples include flaky inorganic oxide particle powders such as phlogopite (artificial mica).

The aspect ratio (diameter / thickness) of the inorganic oxide particle powder (including hydrous aluminum silicate potassium) in the present invention is preferably in the range of 2 to 500, more preferably in the range of 10 to 400, still more preferably, It is in the range of 50-300.
If the aspect ratio is less than 2, the reinforcing effect on the mechanical properties such as creep properties when the flaky composite particle powder is added to the resin composition is small, and it is necessary to increase the amount of addition. Problems such as worsening may occur. When the aspect ratio exceeds 500, for example, uniform coating treatment with alkoxysilane or polysiloxane and uniform adhesion treatment with carbon black on the surface of the hydrated aluminum potassium silicate particles may be difficult.

The average diameter of the inorganic oxide particle powder (including hydrated aluminum potassium silicate) in the present invention is preferably 0.001 mm or more and less than 5 mm. If the average diameter is less than 0.001 mm, aggregation is likely to occur due to particle refinement. For example, uniform coating treatment with alkoxysilane or polysiloxane and uniform adhesion with carbon black on the surface of hydrous potassium aluminum silicate particle powder Processing may be difficult. If the average diameter is 5 mm or more, the resulting carbon black-coated particles are coarse, which is not preferable.
The average diameter means an average of the maximum lengths of the flat surfaces of the plate-like inorganic oxide particles. For example, when the flat surfaces are in the shape of ellipses, rectangles, etc., the average of the lengths of the major axes is calculated. Say. The average diameter can be measured by an image analysis apparatus.

  Considering the uniform coating treatment with alkoxysilane or polysiloxane and the uniform adhesion treatment with carbon black on the surface of the hydrated aluminum potassium silicate particle powder, and the uniform dispersion of the resulting fine carbon black coated particles, The average diameter is preferably in the range of 0.002 to 4 mm, more preferably in the range of 0.005 to 1 mm.

Further, as described above, the flat surface of the inorganic oxide particles may be an elongated shape having a major axis and a minor axis such as an ellipse or a rectangle. In the present invention, the flat surface is a flaky composite. When the particle powder is dispersed in the resin component, the long axis and the short axis are as equal as possible (the flat surface is a circle, a square shape, etc.) so that anisotropy does not occur in the strength (rigidity) of the belt surface. Preferably there is.
Therefore, the aspect ratio (major axis / minor axis) between the major axis and the minor axis of the flat surface of the inorganic oxide particles in the present invention is preferably in the range of 20/1 to 1/1. A range of 1/1 is more preferable.

  The organosilane compound produced from the alkoxysilane in the present invention (hereinafter referred to as “organosilane compound”) is an organosilane compound produced from alkoxysilane.

  Specific examples of the alkoxysilane include methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, isobutyltrimethoxysilane. Examples include methoxysilane and decyltrimethoxysilane.

  Considering the adhesion effect and desorption rate of carbon black to these as described above, the organosilane compound produced from methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, isobutyltrimethoxysilane, and phenyltriethoxysilane is An organosilane compound formed from methyltriethoxysilane, methyltrimethoxysilane and phenyltriethoxysilane is more preferable.

  As the polysiloxane in the present invention, polysiloxane, modified polysiloxane, terminally modified polysiloxane, or a mixture thereof can be used.

  The coating amount of the organosilane compound or polysiloxane is 0.02 to 5.0 mass in terms of Si with respect to the organosilane compound-coated water-containing aluminum potassium silicate particle powder or the polysiloxane-coated water-containing aluminum potassium silicate particle powder. %, More preferably 0.03 to 4.0% by mass, and even more preferably 0.05 to 3.0% by mass.

  When the coating amount is less than 0.02% by mass, it is difficult to attach 5 parts by mass or more of carbon black to 100 parts by mass of the hydrated aluminum potassium silicate particle powder. If it exceeds 5.0% by mass, 5 to 30 parts by mass of carbon black can be adhered to 100 parts by mass of the hydrated aluminum potassium silicate particle powder, so there is no meaning to cover more than necessary.

  In order to form a surface layer on the surface of the inorganic oxide particles and to attach carbon black to the surface layer, mixing and stirring of the hydrated aluminum potassium silicate particle powder and alkoxysilane or polysiloxane, the carbon black and particles It can be carried out by mixing and stirring with the hydrous iron oxide fine particle powder coated with an organosilane compound or polysiloxane formed from alkoxysilane on the surface. A device capable of applying a shearing force is preferable, and in particular, a device that can perform compression simultaneously with shearing, spatula, etc., for example, a wheel-type kneader, a ball-type kneader, a blade-type kneader, or a roll-type kneader. Can do. In carrying out the present invention, a wheel-type kneader can be used more effectively.

  Specific examples of the wheel type kneader include edge runners (synonymous with “mix muller”, “simpson mill”, “sand mill”), multi-mal, stotz mill, wet pan mill, conner mill, and ring muller. , Preferably an edge runner, multi-mal, Stots mill, wet pan mill, and ring muller, and more preferably an edge runner. Specific examples of the ball kneader include a vibration mill. Specific examples of the blade-type kneader include a Henschel mixer, a planetary mixer, and a nauta mixer. Specific examples of the roll-type kneader include an extruder.

  The conditions at the time of mixing and stirring are, for example, a line load of 19.6 to 1960 N / cm (2 to 200 kg / cm so that alkoxysilane or polysiloxane is coated as uniformly as possible on the particle surface of the hydrated potassium aluminum silicate particles. ), Preferably 98 to 1470 N / cm (10 to 150 kg / cm), more preferably 147 to 980 N / cm (15 to 100 kg / cm), and the treatment time is 5 to 120. The treatment conditions may be appropriately adjusted within a range of minutes, preferably within a range of 10 to 90 minutes. In addition, what is necessary is just to adjust process conditions suitably in the range of 2-2000 rpm, Preferably it is the range of 5-1000 rpm, More preferably, it is the range of 10-800 rpm.

  The addition amount of alkoxysilane or polysiloxane is preferably in the range of 0.15 to 45 parts by mass with respect to 100 parts by mass of the hydrated aluminum potassium silicate particle powder that is inorganic oxide particles. When the amount is less than 0.15 parts by mass, it is difficult to adhere the target carbon black. Carbon black can be made to adhere in the range of 5-30 mass parts with respect to 100 mass parts of hydrous aluminum potassium silicate particle powder by the addition amount of the range of 0.15-45 mass parts.

  Next, carbon black is added to the hydrated aluminum potassium silicate particle powder coated with alkoxysilane or polysiloxane, and mixed and stirred to adhere the carbon black to the alkoxysilane coating or polysiloxane coating. If necessary, drying or heat treatment may be further performed.

-Belt composition resin composition-
The resin composition (belt constituent material in which a resin component and flaky composite particle powder and the like are mixed) in the present invention is formed by coating a resin component which is a polyamide resin described later with a surface layer that develops conductivity by electronic conduction. The flaky composite particle powder is mixed well in advance, and then a strong shearing action is applied using a kneader or disperser to break down the agglomerates of the fine particle powder that covers the surface layer containing fine carbon black. The fine particle powder formed by coating the surface layer containing fine carbon black in the resin composition is uniformly dispersed, and then molded into a shape suitable for the purpose.

  The amount of the flaky composite particle powder added is preferably in the range of 5 to 50 parts by mass, more preferably 20 to 45 parts by mass, per 100 parts by mass of the resin component. When the amount is less than 5 parts by mass, it may be difficult to stably obtain a predetermined electric resistance value, and there may be a problem that the effect of reducing the creep deformation amount and the thermal expansion coefficient is small. If it is larger than 50 parts by mass, problems such as deterioration of the belt appearance may occur.

-Polyimide resin-
As the resin component in the present invention, a polyimide resin material having excellent mechanical strength and excellent shape stability over time is used. In addition, as the polyimide resin, a polymer formed by imide bonding of a tetracarboxylic dianhydride having a wholly aromatic skeleton that is a tetracarboxylic acid residue and a diamine component having a diphenyl ether skeleton that is a diamine residue, That is, it is preferable that a polyimide resin having an ether skeleton in the diamine residue is a main component. By using a polyimide resin having an ether skeleton in the diamine residue as a main component, the polyimide resin surface described later can have a flexibility with a surface microhardness of 30 degrees or less.

  Examples of the diamine component having the diphenyl ether skeleton include 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, and compounds obtained by substituting these aromatic rings with lower alkyl groups. Diaminodiphenyl ether is preferred because the resulting belt surface can be made relatively soft.

  Examples of the tetracarboxylic dianhydride having a wholly aromatic skeleton include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4 ′. -Biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalene Examples thereof include tetracarboxylic dianhydrides or compounds obtained by substituting these aromatic rings with lower alkyl groups. Among these, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is particularly preferable.

  The polyimide resin in the present invention is mainly composed of a polymer formed by imide bonding of a tetracarboxylic dianhydride having a wholly aromatic skeleton and a diamine component having a diphenyl ether skeleton, and the surface microhardness of the surface of the polyimide resin. However, if it is 30 degrees or less, a polymer formed by imide bonding between a tetracarboxylic dianhydride having a wholly aromatic skeleton and a diamine component having a p-phenylene skeleton may be included.

  For example, the polyimide resin belt (semiconductive belt) is formed by adding the flaky composite to the polyamic acid solution obtained by polymerizing the tetracarboxylic dianhydride having the wholly aromatic skeleton and the diamine component. A method of developing a mixed liquid containing a desired amount of particle powder by an appropriate method, drying the formed layer to form a film, and heat-treating the molded product to convert the polyamic acid to an imide, etc. Can be performed.

  Also, when forming a seamless belt, for example, a method of immersing the mixed solution in the outer peripheral surface of a cylindrical mold, a method of applying to the inner peripheral surface, a method of further centrifuging, or a method of filling a casting mold Conventional methods such as a method of spreading the ring layer in an appropriate manner, forming the dried layer into a bell-shaped mold, heat-treating the molded product to convert the polyamic acid into an imide, and recovering it from the mold (See JP-A-61-95361, JP-A-62-2514, JP-A-3-180309, etc.). In forming the seamless belt, an appropriate treatment such as mold release treatment or defoaming treatment can be performed.

(Coefficient of thermal expansion by adding flaky composite particle powder)
The thermal expansion coefficient of the resin material by adding the flaky composite particle powder is defined by the composite rule of the flaky composite particle powder. The thermal expansion coefficient of the resin material (composite material) to which the flaky composite particle powder is added is expressed by the following equation (2).
αc = αm (1-vf) + αfVf (2)

  In the above formula (2), αc is the thermal expansion coefficient of the composite material to which the flaky composite particle powder (inorganic filler material) is added, αm is the thermal expansion coefficient of the resin material, and αf is the flaky composite particle powder (inorganic filler). The thermal expansion coefficient Vf of the material) represents the volume fraction of the flaky composite particle powder (inorganic filler).

  Here, the thermal expansion coefficient of the flaky composite particle powder is 4 to 8 ppm / ° K, which is about 1/3 to 1/10, which is 20 to 40 ppm / ° K which is a thermal expansion coefficient of a general resin material. Since it is small in the range, it can be reduced by adding composite particles based on the formula (2) than before adding.

  The thermal expansion coefficient is obtained from the amount of change in the reference length while increasing the temperature at 10 ° C./min using a thermal analysis device TMA-50 manufactured by Shimadzu Corporation as a reference length of 10 mm. Can do.

(Surface micro hardness)
The present inventors have found that there is a very accurate correlation between the surface microhardness of the semiconductive belt and the generation level of the holocharacter. That is, when the surface microhardness is 25 or less, more preferably 15 or less, and still more preferably 15 or less, the semiconductive belt of the present invention is used as an intermediate transfer belt or a paper transport belt in an image forming apparatus described later. In this case, the transfer surface of the belt is deformed by the pressing force of the bias roller, whereby the pressing force concentrated on the toner on the surface of the semiconductive belt is dispersed. For this reason, the toner does not aggregate, and image quality defects such as a holocharacter in which the line image disappears are not generated.

The surface microhardness can be determined by a method of measuring how much the indenter has entered the sample. Hereinafter, a method for measuring the surface microhardness will be described.
FIG. 1 is a schematic cross-sectional view showing the measurement principle of the surface microhardness of the surface layer. In FIG. 1, 60 represents a belt surface, 61 represents a needle-like indenter, and an arrow represents a load applied to the needle-like indenter 61. means.

When measuring the surface microhardness, the tip of the needle-shaped indenter 61 having a predetermined shape is pressed onto the outermost surface portion of the belt surface 60 until the load L (mN) is changed from the load 0 to the predetermined load P. When the biting depth in the vertical direction of the needle-shaped indenter 61 into the belt surface 60 at this time is D (μm), the surface microhardness DH is expressed by the following equation (3).
DH = αP / D ² (3)
Here, α is a constant depending on the shape of the indenter, and α = 3.8854 (used indenter: in the case of a triangular pyramid indenter).

  This surface microhardness is the hardness obtained from the excessive weight and indentation depth in the process of indenting the indenter, and represents the strength characteristics of the material including not only plastic deformation of the sample but also elastic deformation. is there. In addition, the measurement area is very small, and more accurate hardness measurement is possible within a range close to the toner particle diameter.

The surface microhardness of the belt was specifically determined by the following method. A sheet of material (semiconductive belt) 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 addition, the semiconductive belt of the present invention preferably has a Young's modulus of 2500 MPa or more, more preferably 3000 MPa or more, and particularly preferably 4000 MPa or more. The relationship between the Young's modulus of the belt and the amount of displacement of the belt due to disturbance (load fluctuation) during driving of the belt can be expressed by the following equation (4).
Δl = P · l · α / (t · w · E) (4)

In said formula (4), each parameter | index represents the following.
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 )

  As described above, the belt expansion / contraction (displacement amount) due to disturbance (load fluctuation) during belt driving is inversely proportional to the Young's modulus and thickness of the belt material. When a belt having a high Young's modulus (4000 MPa or more) is used, the amount of displacement of the belt due to disturbance (load fluctuation) at the time of driving the belt is reduced, belt deformation due to stress at the time of driving is reduced, and good image quality is stably obtained. be able to. However, when 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 system roll increases, and a good image quality may not be obtained. Further, the deformation amount between the outer side and the inner side of the belt increases, and there may be a problem that the belt breaks due to local repeated stress.

(Surface resistivity)
When the semiconductive belt of the present invention is used as an intermediate transfer belt (intermediate transfer member), the surface resistivity of the semiconductive belt is preferably in the range of 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ω / □, A range of 1 × 10 ¹¹ to 1 × 10 ¹³ Ω / □ is more preferable. When this surface resistivity is higher than 1 × 10 ¹⁴ Ω / □, peeling discharge is likely to occur at the post-nip portion where the latent image carrier and the intermediate transfer member in the primary transfer portion are peeled off, and discharge is generated. In the portion, an image quality defect that causes white spots may occur. On the other hand, when the surface resistivity 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, so the graininess of the image quality deteriorates. Sometimes. Therefore, by setting the surface resistivity within the above range, it is possible to prevent white spots due to discharge that occurs when the surface resistivity is high and deterioration of image quality that occurs when the surface resistivity is low.

  Further, the in-plane variation of the surface resistivity is preferably 1.2 (logΩ / □) or less, and more preferably 0.8 (logΩ / □) or less. When the in-plane variation is 1.2 (log Ω / □) or less, a transfer voltage can be applied uniformly, and a uniform transfer image quality can be obtained. In addition, since there are few locally highly conductive parts, the problem that the surface resistivity is locally reduced is less likely to occur. Here, the in-plane variation of the surface resistivity refers to a difference in common logarithm between the maximum value and the minimum value of the surface resistivity in the semiconductive belt surface.

The surface resistivity can be measured according to JIS K6991 using a circular electrode (for example, “HR probe” of Hiresta IP manufactured by Mitsubishi Oil Chemical Co., Ltd.). The method for measuring the surface resistivity will be described with reference to FIG. FIG. 2 is a schematic plan view (a) and a schematic cross-sectional view (b) showing an example of a circular electrode. The circular electrode shown in FIG. 2 includes a first voltage application electrode A and a plate-like insulator B. The first voltage application electrode A has a cylindrical electrode portion C and a cylindrical ring electrode having an inner diameter larger than the outer diameter of the cylindrical electrode portion C and surrounding the cylindrical electrode portion C at a constant interval. Part D is provided. The intermediate transfer body T is sandwiched between the cylindrical electrode portion C and the ring electrode portion D in the first voltage application electrode A and the plate insulator B, and the cylindrical electrode portion C and the ring in the first voltage application electrode A are sandwiched. The current I (A) flowing when the voltage V (V) is applied to the electrode portion D is measured, and the surface resistivity ρs (Ω / Ω) of the transfer surface of the intermediate transfer member T is calculated by the following equation (5). □) can be calculated. Here, in the following formula (5), d (mm) indicates the outer diameter of the cylindrical electrode portion C, and D (mm) indicates the inner diameter of the ring-shaped electrode portion D.
ρs = π × (D + d) / (D−d) × (V / I) (5)

(Volume resistivity)
When the semiconductive belt of the present invention is used as an intermediate transfer member (intermediate transfer member), the volume resistivity of the semiconductive belt is preferably in the range of 1 × 10 ⁸ to 1 × 10 ¹³ Ωcm. A range of 10 ⁹ to 1 × 10 ¹² Ωcm is more preferable. When this volume resistivity is less than 1 × 10 ⁸ Ωcm, the electrostatic force that holds the charge of the unfixed toner image transferred from the latent latent image carrier to the intermediate transfer member becomes difficult to work. The electrostatic repulsive force between the toners or the fringe electric field near the image edge may cause the toner to scatter around the image (blur), resulting in the formation of a noisy image. On the other hand, if the volume resistivity is higher than 1 × 10 ¹³ [Omega] cm, in order retention of charge is large, it is necessary to neutralizing mechanism for the intermediate transfer member surface by the transfer electric field at the primary transfer is charged Sometimes. Therefore, by setting the volume resistivity 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 can be measured in accordance with JIS K6991 using a circular electrode (for example, HR probe of Hirester IP manufactured by Mitsubishi Yuka Co., Ltd.). A method for measuring the volume 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. The circular electrode shown in FIG. 3 includes a first voltage application electrode A ′ and a second voltage application electrode B ′. The first voltage application electrode A ′ has a cylindrical electrode part C ′ and a cylindrical shape having an inner diameter larger than the outer diameter of the cylindrical electrode part C ′ and surrounding the cylindrical electrode part C ′ at a constant interval. Ring-shaped electrode portion D ′. The intermediate transfer body T is sandwiched between the cylindrical electrode portion C ′ and the ring-shaped electrode portion D ′ and the second voltage application electrode B ′ in the first voltage application electrode A ′, and the circle in the first voltage application electrode A ′. The current I (A) that flows when the voltage V (V) is applied between the columnar electrode portion C ′ and the second voltage application electrode B ′ is measured, and the volume of the intermediate transfer member T is calculated by the following equation (6). The resistivity ρv (Ωcm) can be calculated. Here, in the following formula (6), t represents the thickness of the intermediate transfer member T.
ρv = 19.6 × (V / I) × t (6)

When the semiconductive belt of the present invention is used as a paper conveying belt, the volume resistivity is preferably in the range of 1 × 10 ⁶ to 1 × 10 ¹² Ωcm. When the volume resistivity is less than 1 × 10 ⁶ Ωcm, toner may be scattered around the image. When the volume resistivity exceeds 1 × 10 ¹² Ωcm, it is necessary for transfer. The electric field may increase, and the burden on the power source for applying a voltage to the belt may increase.

  When the semiconductive belt of the present invention is used as an intermediate transfer belt (intermediate transfer member), the electric field dependency of the surface resistivity of the transfer surface of the intermediate transfer belt may be 0.7 (log Ω / □) or less. Preferably, 0.5 (log Ω / □) is suitable. If the electric field dependency of the surface resistivity is 0.7 (log Ω / □) or less, the electric field concentration due to the transfer voltage as described above is less likely to occur. In the halftone image, it is possible to prevent the occurrence of image quality defects such as the paper running section being white. The electric field dependency of the surface resistivity indicates a difference in common logarithm of the surface resistivity obtained by applying a voltage of 100 V and a voltage of 1000 V to the semiconductive belt.

  When the semiconductive belt of the present invention is used as an intermediate transfer belt (intermediate transfer member), the common logarithm of the surface resistivity at 30 ° C. and 85% RH and the surface resistivity at 10 ° C. and 15% RH is used. The difference is preferably 1.0 or less (logΩ / □), and more preferably 0.6 or less (logΩ / □). In the present invention, by using the electron conductive conductive agent, the difference in the common logarithm of the surface resistivity depending on the environment between 30 ° C. and 85% RH and 10 ° C. and 15% RH is 1.0 or less. Can be suppressed.

  Even when the semiconductive belt according to the present invention is used as a paper conveying belt, the electric field dependency and the environment dependency of the surface resistivity are required to be about the same as those used for the intermediate transfer belt.

  The semiconductive belt of the present invention described above can be suitably applied as, for example, an intermediate transfer member in an image forming apparatus or a paper transport belt.

<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 and a paper transport belt type image forming apparatus. For example, a normal monocolor image forming apparatus that contains only a single color toner in the developing device, or a color that repeats primary transfer of a toner image carried on a latent latent image carrier such as a photosensitive drum to an intermediate transfer body in sequence. The present invention is applied to an image forming apparatus, a tandem type color image forming apparatus in which a plurality of latent latent image carriers having developing units for respective colors are arranged in series on an intermediate transfer member.

  Hereinafter, a color image forming apparatus that repeats primary transfer will be described as an example of the image forming apparatus of the present invention. FIG. 4 is a schematic configuration diagram showing an example of the image forming apparatus of the present invention.

  4 includes a photosensitive drum 1 as a latent image carrier, an intermediate transfer belt 2 as an intermediate transfer member, a bias roll 3 as a transfer electrode, a tray 4 for supplying recording paper as a recording medium, and Bk. (Black) toner developing device 5, Y (yellow) toner developing device 6, M (magenta) toner developing device 7, C (cyan) toner developing device 8, belt cleaner 9, peeling claw 13, belt roll 21 , 23 and 24, backup roll 22, conductive roll 25, electrode roll 26, cleaning blade 31, pickup roll 42, and feed roll 43. The intermediate transfer belt 2 includes the semiconductive belt of the present invention.

In FIG. 4, the photosensitive drum 1 rotates in the direction of arrow A, and its surface is uniformly charged by a charging device (not shown). An electrostatic latent image of the first color (for example, Bk) is formed on the charged photosensitive drum 1 by image writing means such as a laser writing device. The electrostatic latent image is developed by the developing device 5 to form a visualized toner image T. The toner image T reaches the primary transfer portion where the conductive roll 25 is disposed by the rotation of the photosensitive drum 1, and an electric field having a reverse polarity is applied from the conductive roll 25 to the toner image T, whereby the toner image T Is transferred to the transfer belt 2 while being electrostatically attracted to the transfer belt 2 by the rotation in the arrow B direction.
Thereafter, similarly, a second color toner image, a third color toner image, and a fourth color toner image are sequentially formed and superimposed on the surface of the transfer belt 2 to form a multiple toner image.

  The multiple toner image transferred to the intermediate transfer belt 2 reaches the secondary transfer portion where the bias roll 3 is installed by the rotation of the intermediate transfer belt 2. The secondary transfer unit includes a bias roll 3 installed on the surface side of the transfer belt 2 on which the toner image is carried, a backup roll 22 arranged to face the bias roll 3 from the back side of the intermediate transfer belt 2, and The electrode roll 26 is configured to rotate in pressure contact with the backup roll 22.

  The recording paper 41 (recording medium) is taken out one by one from the recording paper bundle accommodated in the recording paper tray 4 by the pickup roll 42, and is fed between the transfer belt 2 and the bias roll 3 of the secondary transfer section by the feed roll 43. Are fed at a predetermined timing. The toner image carried on the surface of the intermediate transfer belt 2 is transferred to the fed recording paper 41 by the pressure contact conveyance by the bias roll 3 and the backup roll 22 and the rotation of the intermediate transfer belt 2.

The recording paper 41 to which the toner image has been transferred is peeled from the transfer belt 2 by operating the peeling claw 13 in the retracted position until the primary transfer of the final toner image is completed, and is conveyed to a fixing device (not shown). The toner image is fixed to the recording paper 41 by heat treatment, and is made a permanent image.
The intermediate transfer belt 2 on which the transfer of the multiple toner images to the recording paper 41 has been completed is subjected to removal of residual toner by a belt cleaner 9 provided downstream of the secondary transfer portion, and is prepared for the next transfer. A cleaning blade 31 made of polyurethane or the like is always in contact with the bias roll 3 to remove foreign matters such as toner particles and paper dust adhered during transfer.

In the case of transfer of a single color image, the toner image T that has been primarily transferred is immediately secondarily transferred and conveyed to the fixing device. However, in the case of transfer of a multicolor image by superimposing a plurality of colors, the toner image of each color is primary. The rotation of the intermediate transfer belt 2 and the photosensitive drum 1 is synchronized so that the toner images of the respective colors do not shift so that they coincide accurately at the transfer portion.
In the secondary transfer section, an output pressure (transfer voltage) having the same polarity as the polarity of the toner image is applied to the electrode roll 26 that is in pressure contact with the backup roll 22 that is disposed to face the bias roll 3 and the transfer belt 2. As a result, the toner image is transferred to the recording paper 41 by electrostatic repulsion.
As described above, an image can be formed.

Next, a tandem color image forming apparatus will be described as another preferred example of the image forming apparatus of the present invention. FIG. 5 is a schematic configuration diagram showing another example of the image forming apparatus of the present invention.
The image forming apparatus shown in FIG. 5 includes image forming units 100Y, 100M, 100C, and 100Bk, a paper transport belt 106, transfer rolls 107Y, 107M, 107C, and 107Bk, a paper transport roll 108, and a fixing device 109. doing. The paper conveying belt 106 includes the semiconductive belt of the present invention.

  The image forming units 100Y, 100M, 100C, and 100Bk are respectively provided with photosensitive drums (latent image carriers) 101Y, 101M, 101C, and 101Bk that rotate at a predetermined peripheral speed (process speed) in the clockwise direction of an arrow. Around the photosensitive drums 101Y, 101M, 101C, and 101Bk, there are scorotron chargers 102Y, 102M, 102C, and 102Bk, exposure units 103Y, 103M, 103C, and 103Bk, and color developing units (yellow developing unit 104Y and magenta developing unit). 104M, cyan developing device 104C, black developing device 104Bk), and photoreceptor cleaners 105Y, 105M, 105C, 105Bk, respectively.

  The four image forming units 100Y, 100M, 100C, and 100Bk are arranged in parallel with the sheet conveying belt 106 in the order of the image forming units 100Y, 100M, 100C, and 100Bk, but the image forming units 100Bk, 100Y, and 100C are arranged. , 100M order, etc., an appropriate order can be set according to the image forming method.

  The paper transport belt 106 can be rotated by the support rolls 110, 111, 112, 113 in the counterclockwise direction indicated by the arrow at the same peripheral speed as the photosensitive drums 101Y, 101M, 101C, 101Bk. The photosensitive drums 101Y, 101M, 101C, and 101Bk located in the middle of each of the photosensitive drums 101 and 101Bk are arranged so as to contact each other. The sheet conveying belt 106 is provided with a belt cleaning device 114. The support roll 111 plays the role of a tension roll, and is arranged so as to be movable in the direction of the surface of the paper transport belt 106, and can adjust the tension of the paper transport belt 106.

  The transfer rolls 107Y, 107M, 107C, and 107Bk are disposed inside the paper transport belt 106 at positions facing the portions where the paper transport belt 106 is in contact with the photosensitive drums 101Y, 101M, 101C, and 101Bk, respectively. A transfer region (nip portion) for transferring the toner image onto the recording paper (recording medium) P is formed via the photosensitive drums 101Y, 101M, 101C, and 101Bk and the paper transport belt 106.

  The recording paper P is transported to the paper transport belt 106 by the paper transport roll 108. The fixing device 109 is arranged so that the recording paper P can be transported after the recording paper P passes through the transfer regions (nip portions) of the paper transport belt 106 and the photosensitive drums 101Y, 101M, 101C, and 101Bk. ing.

For example, in the image forming unit 100Bk of the image forming apparatus shown in FIG. 5, when the photosensitive drum 101Bk is driven to rotate, a predetermined voltage is applied to the surface of the photosensitive drum 101Bk by the scorotron charger 102Bk.・ Electrically charged to potential. The photosensitive drum 101Bk whose surface is uniformly charged is then exposed by the exposure device 103Bk, and an electrostatic latent image is formed on the surface.
Subsequently, the electrostatic latent image is developed by the black developing device 104Bk, and a toner image is formed on the surface of the photosensitive drum 101Bk.

This toner image is electrostatically attracted to the paper conveyance belt 106 and is transferred to the surface of the recording paper P conveyed to the transfer area (nip portion) between the photosensitive drum 101Bk and the paper conveyance belt 106. Simultaneously with the transfer, the image is transferred by the electric field formed by the transfer bias applied from the transfer roll 107Bk.
Thereafter, the toner remaining on the surface of the photosensitive drum 101Bk is cleaned and removed by the photosensitive cleaner 105Bk. The photosensitive drum 101Bk is subjected to the next charging / developing / transfer cycle.
The above cycle is similarly performed in the image forming units 100C, 100M, and 100Y. On the other hand, the recording paper P is conveyed to a transfer position in the next image forming unit.

As described above, the recording paper P onto which the toner images are sequentially transferred by the transfer rolls 107Bk, 107C, 107M, and 107Y is further conveyed to the fixing device 109 and fixed.
Thus, a desired image is formed on the surface of the recording paper P.

  Furthermore, when the semiconductive belt of the present invention is incorporated and used as an intermediate transfer belt or transfer / conveying belt in an image forming apparatus, it is preferable to use a spherical toner as the toner. By using spherical toner as the toner, the material constituting the transfer surface has low surface hardness and high volume resistance, and can further improve transfer efficiency. High quality transfer image quality can be obtained.

Here, the spherical toner means a toner having a shape factor (ML ² / A) in the range of 100 to 140. The shape factor is preferably in the range of 100 to 130, more preferably in the range of 100 to 120. When this shape factor (ML ² / A) is larger than 140, the transfer efficiency is lowered, and the deterioration of the image quality of the print sample can be visually confirmed.

Here, the shape factor (ML ² / A) is a factor defined by the following equation (1).
(ML ² / A) = (absolute maximum length of toner particles) ² / (projected area of toner particles) × (π / 4) × 100 (1)
The absolute maximum length of the toner particles and the projected area of the toner particles are measured by using an optical microscope image of the toner dispersed on the slide glass using a Luzex image analyzer (manufactured by Nireco Corporation, LUZEX III). Through a Luzex image analyzer and processed by image processing.

  The spherical toner in the present invention contains at least a binder resin and a colorant. As the spherical toner, particles having a volume average particle diameter in the range of 2 to 12 μm, more preferably particles having a volume average particle diameter in the range of 3 to 9 μm can be used.

  Examples of the binder resin include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate, and acrylic acid. Α-methylene aliphatic monocarboxylic acid esters such as methyl, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; Homopolymers and copolymers of vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone; Particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-anhydrous maleate. Examples include acid copolymers, polyethylene, and polypropylene. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax, and the like can also be mentioned.

  Examples of the colorant include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and lamp. Black, Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be cited as a representative example.

  The spherical toner may be internally added or externally added with known additives such as a charge control agent, a release agent, and other inorganic fine particles. Typical examples of the release agent include low molecular polyethylene, low molecular polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination.

As other inorganic fine particles, small-diameter inorganic fine particles having an average primary particle size of 40 nm or less are used for the purpose of powder flowability, charge control, etc., and if necessary, larger diameters are used to reduce adhesion. Inorganic or organic fine particles may be used in combination. As these other inorganic fine particles, known ones can be used. Examples thereof include silica, alumina, titania, metatitanic acid, zinc oxide, zirconia, magnesia, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide, and strontium titanate.
In addition, the surface treatment of the small-diameter inorganic fine particles is effective because the dispersibility becomes high and the effect of increasing the powder fluidity increases.

  The spherical toner is not particularly limited by the production method, and can be obtained by a known method. Specifically, for example, a kneading and pulverizing method in which a binder resin and a colorant and, if necessary, a release agent and a charge control agent are kneaded, pulverized and classified, and particles obtained by the kneading and pulverizing method are mechanically impacted. Method of changing shape by force or heat energy, emulsion polymerization of binder resin polymerizable monomer, dispersion of formed dispersion, colorant, release agent and charge control agent as required Liquid emulsion, agglomeration, heat fusion to obtain spherical toner, emulsion polymerization aggregation method, polymerizable monomer for obtaining binder resin, colorant, release agent if necessary, charge control agent A suspension polymerization method in which a solution such as a suspension is polymerized by suspending in an aqueous solvent, a binder resin and a colorant, and a release agent and a charge control agent as necessary are suspended in an aqueous solvent and granulated. Examples thereof include a dissolution suspension method. Further, a manufacturing method may be performed in which the spherical toner obtained by the above method is used as a core, and further, aggregated particles are attached and heat-fused to give a core-shell structure. When the external additive is added, it can be produced by mixing the spherical toner and the external additive with a Henschel mixer or a V blender. In addition, when the spherical toner is manufactured by a wet method, it can be externally added by a wet method.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention. In addition, it is not limited to the resin material used as an example.

<Example 1>
(Production of flaky composite particle powder (A))
Hydrous aluminum potassium silicate particle powder (mascobite, KAl ₂ AlSi ₃ O ₁₀ (OH) ₂ , average diameter: 1 mm, aspect ratio (diameter / thickness): 100, aspect ratio (major axis / minor axis): 3) 1 .1 kg is put into edge runner “MPUV-2 type” (product name, manufactured by Matsumoto Casting Iron Works Co., Ltd.), and 22 g of methyltriethoxysilane (trade name: TSL8123, manufactured by Toshiba Silicone Co., Ltd.) is added with 20 ml of ethanol. The methyltriethoxysilane solution obtained by mixing and diluting was added to the hydrated aluminum potassium silicate particle powder while operating the edge runner, and mixed and stirred for 20 minutes at a linear load of 392 N / cm (40 kg / cm). . In addition, the stirring speed at this time was 22 rpm.

  Next, as carbon black, oxidized carbon black (SPECIAL BLACK4 (manufactured by Degussa, pH: 3.0, volatile content: 14.0% by mass), 110 g was added over 10 minutes while operating the edge runner. Further, the mixture was stirred for 20 minutes with a linear load of 392 N / cm (40 kg / cm) to deposit carbon black on the methyltriethoxysilane coating (surface layer), and then at 105 ° C. using a dryer. Heat treatment was performed for 60 minutes to obtain a flaky composite particle powder (A) coated with a surface layer containing carbon black, at which the stirring speed was 22 rpm.

  The obtained fine flaky composite particle powder (A) was a plate-like particle powder having an average diameter of 0.01 mm and an aspect ratio (diameter / thickness) of 10 to 100. Moreover, the coating amount of the organosilane compound produced from methyltriethoxysilane was 0.30% by mass in terms of Si.

(Preparation of polyamic acid solution (A))
N-methyl-2pyrrolidone (NMP) solution of polyamic acid composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-diaminodiphenyl ether (DDE) (Ube Industries) The flaky composite particle powder (A) coated with the carbon black surface layer is added to Euvarnish A, solid content: 18% by mass) to 34 parts by mass with respect to 100 parts by mass of the polyimide resin solid content. Then, using a collision type disperser (GeanusPY made by Sinus), with a pressure of 200 MPa and a minimum area of 1.4 mm ² , collided after being divided into two parts, passed again through the path divided into two parts, mixed, and flaky A polyamic acid solution (A) in which the composite particle powder was mixed was obtained.

(Production of semiconductive belt)
The polyamic acid solution (A) was applied to the inner surface of a cylindrical mold having an inner diameter of 170 mm and a length of 550 mm to a thickness of 0.5 mm via a dispenser, and rotated at 1500 rpm for 15 minutes to form a spread layer having a uniform thickness. Thereafter, while rotating at 250 rpm, hot air of 60 ° C. was applied from the outside of the mold for 30 minutes, heated at 150 ° C. for 60 minutes, and then cooled to room temperature. Next, the polyimide precursor in which the flaky composite particle powder obtained in this state is dispersed is coated on a metal core body having an outer diameter of 168 mm and a length of 500 mm, and the temperature rising rate is 2 ° C./min up to 360 ° C. The mixture was further heated at 360 ° C. for 30 minutes to remove the solvent, dehydrated ring-closing water, and complete the imide conversion reaction. Thereafter, the temperature was returned to room temperature, and it was peeled off from the metal core to obtain the intended semiconductive belt.
The total thickness of this semiconductive belt was 0.08 mm, the width was 350 mm, and the outer diameter was 168 mm.

<Example 2>
(Preparation of polyamic acid solution (B))
As tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) are combined in a molar ratio of 2: 1. The flaky composite particle powder produced in Example 1 in an N-methyl-2-pyrrolidone (NMP) solution of polyamic acid composed of 4,4′-diaminodiphenyl ether (DDE) as a diamine component (solid content 20 mass%) Is added to 32 parts by mass with respect to 100 parts by mass of the polyimide resin solid content, and collision is performed after splitting into ^two at a pressure of 200 MPa and a minimum area of 1.4 mm ² using a collision type disperser (GeanusPY manufactured by Seanas). The polyamic acid solution (B) in which the flaky composite particle powder was dispersed was obtained by allowing the mixture to pass through a path that was divided into two parts again and mixing.

(Production of semiconductive belt)
In the same manner as in Example 1, the intended semiconductive belt was obtained. The total thickness of this semiconductive belt was 0.08 mm, the width was 350 mm, and the outer diameter was 168 mm.

<Example 3>
(Production of flaky composite particle powder (B))
In the production of the flaky composite particle powder (A) of Example 1, instead of SPECIAL BLACK4, as the carbon black, an oxidized carbon black having a pH of 4.5 (Printex 140V, manufactured by Degussa, pH: 4.5, volatile content: A flaky composite particle powder (B) was produced in the same manner as in Example 1 except that 5% by mass) was used.

(Preparation of polyamic acid solution (C))
As tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) are combined in a molar ratio of 2: 1. The flaky composite particle powder (B) is added to an N-methyl-2-pyrrolidone (NMP) solution of polyamic acid composed of 4,4′-diaminodiphenyl ether (DDE) as a diamine component (solid content: 20% by mass). Add to 30 parts by mass with respect to 100 parts by mass of polyimide resin solids, and use collision type disperser (GeanusPY from Seanas), pressure 200 MPa, minimum area 1.4 mm ² The polyamic acid solution (C) in which the flaky composite particle powder was dispersed was obtained by allowing the mixture to pass through a path that was divided into two parts again and mixing.

(Production of semiconductive belt)
In the same manner as in Example 1, the intended semiconductive belt was obtained. The total thickness of this semiconductive belt was 0.08 mm, the width was 350 mm, and the outer diameter was 168 mm.

<Comparative Example 1>
(Preparation of polyamic acid solution (D))
N-methyl-2-pyrrolidone (NMP) solution of polyamic acid consisting of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA) (Uwanisu S manufactured by Ube Industries) , Solid content: 18% by mass), and Ketchen Black EC (pH: 9.0, volatile content: 1.5% by mass) manufactured by Lion Aguso Co., Ltd. as dry carbon black with respect to 100 parts by mass of polyimide resin solid content. Then, using a collision-type disperser (GeanusPY manufactured by Seanas), the collision is performed after two divisions at a pressure of 200 MPa and a minimum area of 1.4 mm ² , and again divided into two parts five times. The solution was passed through and mixed to obtain a polyamic acid solution (D) in which carbon black was dispersed.

(Production of semiconductive belt)
The polyamic acid solution (D) was applied to the inner surface of a cylindrical mold having an inner diameter of 170 mm and a length of 550 mm to a thickness of 0.5 mm via a dispenser, and rotated at 1500 rpm for 15 minutes to form a spread layer having a uniform thickness. Thereafter, while rotating at 250 rpm, hot air of 60 ° C. was applied from the outside of the mold for 30 minutes, heated at 150 ° C. for 60 minutes, and then cooled to room temperature. Next, the carbon black-containing dispersed polyimide precursor obtained in this state was coated on a metal core having an outer diameter of 168 mm and a length of 500 mm, and the temperature was raised to 400 ° C. at a rate of 2 ° C./min. Furthermore, the mixture was heated at 400 ° C. for 30 minutes to remove the solvent, dehydrated ring-closing water, and complete the imide conversion reaction. Thereafter, the temperature was returned to room temperature, and it was peeled off from the metal core to obtain the intended semiconductive belt.
The total thickness of this semiconductive belt was 0.08 mm, the width was 350 mm, and the outer diameter was 168 mm.

<Comparative Example 2>
(Preparation of polyamic acid solution (E))
As tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) are combined at a molar ratio of 1: 1, As a diamine component, N-methyl-2-pyrrolidone (NMP) solution of polyamic acid composed of 4,4′-diaminodiphenyl ether (DDE) (solid content 20% by mass) and dried carbon black (acetylene black, electrochemical industry) Co., Ltd., pH: 5.7, volatile content: 0.89% by mass) is added to 100 parts by mass of the polyimide resin solids so as to be 15 parts by mass. column at a pressure 200 MPa, the minimum area collide after two split 1.4 mm ^2, by passing five times a path divided into two again, mixed, acidic carbon To obtain a rack containing polyamic acid solution (E).

(Production of semiconductive belt)
In the same manner as in Example 1, the intended semiconductive belt was obtained. The total thickness of this semiconductive belt was 0.08 mm, the width was 350 mm, and the outer diameter was 168 mm.

<Reference example>
Resin composition obtained by dispersing 26 parts by mass of flaky composite particle powder (A) prepared in Example 1 in 100 parts by mass of resin using crystalline polyester PCTG5445 manufactured by Eastman Chemical Co., Ltd. as a resin component. Got. Further, the resin composition pellets were extruded into a tube shape at a heating temperature of 220 ° C. using a single screw extruder to obtain an endless belt having a thickness of 0.13 mm, a width of 350 mm, and an outer diameter of 168 mm. It was.

<Evaluation>
Regarding the semiconductive belts obtained in Examples 1 to 3, Comparative Examples 1 and 2 and Reference Example, in-plane variation of surface resistivity, volume resistivity and surface resistivity (maximum common logarithm of surface resistivity) Value and minimum value), surface resistivity 28 ° C, 85% RH high temperature high humidity environment (H / H environment) and 10 ° C 15% RH low temperature low humidity environment (L / L environment) Difference in logarithmic value, surface microhardness, thermal expansion coefficient, Young's modulus, transfer image quality evaluation, change in surface resistivity after 3000 copies of postcards (difference in common logarithm), and 3000 copies of postcards Later, the occurrence of white spots when copying a halftone of 30% magenta was evaluated. These results are shown in Table 1.

In addition, regarding each said measurement, it carried out as follows.
(Surface resistivity)
As described above, the surface resistivity is measured using the circular electrode shown in FIG. 2 (High Lester IP HR probe manufactured by Mitsubishi Yuka Co., Ltd.) and the cylindrical electrode portion C and ring of the first voltage application electrode A. A voltage of 100 (V) was applied between the electrode part D and the current value after 10 seconds.

(Volume resistivity)
As described above, the volume resistivity is measured using the circular electrode shown in FIG. 3 (HR probe of Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd.) and the cylindrical electrode portion C ′ in the first voltage application electrode A ′. A voltage of 100 (V) was applied between the second voltage application electrode B ′ and the current value after 30 seconds was obtained.

(In-plane variation of surface resistivity)
The in-plane variation of the surface resistivity (difference between the maximum value and the minimum value) was obtained by dividing the produced intermediate transfer belt having an outer diameter of 168 mm and a width of 350 mm into 8 parts in the length direction and 3 parts in the width direction. The surface resistivity was measured for the points, the logarithm of the surface resistivity was taken, and the difference between the maximum value and the minimum value was regarded as variation (ΔR).

(Environmental fluctuation range of surface resistivity)
The environmental fluctuation range of the surface resistivity is the common logarithm of the surface resistivity ρs3 (Ω / □) at 30 ° C. and 85% RH and the common pair of the surface resistivity ρs4 (Ω / □) at 10 ° C. and 15% RH. The difference from the numerical value was calculated as | logρs3−logρs4 |.

(Surface micro hardness)
About the obtained semiconductive belt, it measured on condition of the following using the apparatus (Ultra micro hardness meter DUH-201S (made by Shimadzu Corporation)) shown in FIG.
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

(Coefficient of thermal expansion)
The thermal expansion coefficient is a reference length from 20 ° C. to 80 ° C. while using a thermal analysis device TMA-50 manufactured by Shimadzu Corporation, with a sample length of 10 mm as the reference length and increasing the temperature at 10 ° C./min. It calculated | required from the variation | change_quantity and evaluated by the following references | standards.
○: Less than 40 ppm ×: 40 ppm or more

(Young's modulus)
In accordance with JISK6251, a semiconductive belt was punched into a JIS3 shape and subjected to a tensile test. A tangent line was drawn to the curve in the initial strain region of the obtained stress / strain curve, and the Young's modulus was obtained from the slope.

(Evaluation of transfer image quality)
The obtained semiconductive belt is attached to Fuji Xerox Co., Ltd. Docu Color 1255CP having the structure shown in FIG. 4 as an intermediate transfer belt, and a toner having a shape factor ML ² / A of 115 is used as a toner. Evaluated.

-Holocharacter evaluation-
The occurrence of holocharacters was evaluated according to the following criteria.
○: No occurrence of holo-character △: Little occurrence of holo-character, no problem in image quality ×: Some occurrence of holo-character, there is a problem in image quality

-Color registration (color shift) evaluation-
The occurrence of color misregistration when copying images was evaluated according to the following criteria.
○: No color misregistration △: Color misregistration is slight and there is no problem in image quality ×: Color misregistration occurs and there is a problem in image quality

-Evaluation of white spots-
After 3000 copies of postcards were continuously copied, the occurrence of white spots when copying a halftone of 30% magenta was evaluated according to the following criteria.
○: No white spot occurs ×: White spot occurs and there is a problem in image quality

  Here, as shown in FIG. 6, in a low-temperature and low-humidity environment of 10 ° C. and 15% RH, the sheet (postcard) continuously travels and 3000 sheets are continuously copied. A decrease occurs ((a) in FIG. 6). When a halftone of 30% magenta is copied in a state where the sheet traveling unit 201 is lower than the surrounding surface resistivity by, for example, 1.1 (logΩ / □) or more, the sheet traveling has a lower resistance than the non-sheet traveling unit 202. It becomes difficult to print on the part 201 ((b) in FIG. 6). As a result, white spots occur.

  Here, as shown in FIG. 7, for example, immediately after the secondary transfer, the surface of the intermediate transfer belt 2 is charged to the plus side, and the belt side of the recording paper 41 is charged to the minus side. Therefore, it is considered that peeling discharge is generated between the intermediate transfer belt 2 and the recording paper 41, and the surface of the intermediate transfer belt 2 is deteriorated.

  From the results in Table 1, the semiconductive belts of Examples 1 to 3 of the present invention have no variation in surface resistivity, and the surfaces in a high temperature and high humidity (H / H) environment and a low temperature and low humidity (L / L) environment. It can be seen that excellent environmental image quality can be obtained stably over a long period of time with little environmental variation in resistivity. On the other hand, Comparative Example 1 and Comparative Example 2 disperse carbon black, which is an electron conductive conductive agent, and there is little environmental variation in resistance, but the variation in surface resistivity (ΔR) in the belt surface is large, It can be seen that there is a problem that image quality defects (white spots) occur in continuous copying of 3000 sheets.

  Moreover, since the comparative example 1 had the hard surface, the image quality defect (holo character) generate | occur | produced. In Comparative Example 2, there was a problem that the color registration was poor because the coefficient of thermal expansion was large and the Young's modulus was small. Further, since carbon black that has not been oxidized is used as a conductive agent, image quality defects (white spots) occurred when copying a halftone of 30% magenta after continuously copying 3000 postcards. In the reference example, excellent characteristics were exhibited as a whole, but a slight color shift was observed due to the small Young's modulus.

It is a figure which shows the measuring method of surface micro hardness. It is the schematic plan view (a) and schematic sectional drawing (b) which show an example of the circular electrode which measures surface resistivity. It is the schematic plan view (a) and schematic sectional drawing (b) which show an example of the circular electrode which measures volume resistivity. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention. It is a schematic block diagram which shows another example of the image forming apparatus of this invention. FIG. 10 is an explanatory diagram showing a white-out occurrence state when copying a postcard of 3000 sheets continuously and then copying a halftone of 30% magenta. It is explanatory drawing for demonstrating the fall of the surface resistivity of the secondary transfer part of an intermediate transfer body.

Explanation of symbols

1 Photosensitive drum (latent image carrier)
2 Intermediate transfer belt (intermediate transfer member)
3 Bias roller (second transfer means)
4 Paper tray 5 Black developing device 6 Yellow developing device 7 Magenta developing device 8 Cyan developing device 9 Intermediate transfer member cleaner 10 Transfer roller 13 Peeling claw 14 Conveying belt 16 Photoconductor cleaner 21 Belt roller 22 Backup roller 23 Belt roller 24 Belt roller 25 Conductive roller (first transfer means)
26 Electrode roller 30 Intermediate transfer drum 31 Cleaning blade 41 Recording paper 42 Pickup roller 43 Feed roller 60 Belt surface 61 Needle-shaped indenter

Claims (11)

A semiconductive belt used in an electrophotographic image forming apparatus,
A semiconductive belt comprising a flaky composite particle powder containing a polyimide resin as a resin component and coated with a surface layer exhibiting conductivity by electronic conduction.   The semiconductive belt according to claim 1, wherein the flaky composite particle powder is formed by coating a surface layer containing carbon black on the surface of the inorganic oxide particle powder.   The flaky composite particle powder is formed by coating a surface layer containing carbon black on the surface of a hydrated aluminum potassium silicate particle powder having an aspect ratio (diameter / thickness) of 2 to 500. Item 3. The semiconductive belt according to Item 1 or 2.   The flaky composite particle powder is formed by coating the surface of the hydrated aluminum potassium silicate particle powder with a surface layer containing an organosilane compound or polysiloxane generated from alkoxysilane, and carbon black is adhered to the surface layer. The semiconductive belt according to any one of claims 1 to 3, wherein the average diameter is 0.001 mm or more and less than 5 mm.   5. The semiconductive belt according to claim 1, wherein the content of the flaky composite particle powder is in the range of 5 to 50 parts by mass per 100 parts by mass of the resin component.   The semiconductive belt according to any one of claims 2 to 5, wherein the carbon black is acidic carbon black having a pH of 5 or less.   The polyimide resin is a polymer formed by imide bonding of a tetracarboxylic dianhydride having a wholly aromatic skeleton and a diamine component using 4,4′-diaminophenyl ether as a main component. The semiconductive belt according to any one of claims 1 to 6.   An intermediate transfer member comprising the semiconductive belt according to claim 1.   An image forming apparatus using the semiconductive belt according to claim 1 as an intermediate transfer belt.   An image forming apparatus using the semiconductive belt according to claim 1 as a paper conveying belt.   11. The image forming apparatus according to claim 9, wherein the image forming apparatus includes at least a latent image carrier and an intermediate transfer belt and / or a paper transport belt, wherein the latent image carrier is plural. apparatus.

Images