JP2008102323A - Semiconductive belt and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductive belt hardly causing micro-slip and capable of suppressing deterioration in color registration, and an image forming apparatus equipped with the same. <P>SOLUTION: The semiconductive belt is equipped with a base material, and a surface layer provided on the base material, containing conductive organic fiber, and having durometer hardness of A30 to A70. The image forming apparatus is equipped with the semiconductive belt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductive belt and an image forming apparatus using the semiconductive belt.

In an image forming apparatus using an electrophotographic method, first, a uniform charge is formed on the surface of an image carrier made of a photoconductive photoconductor made of an inorganic or organic material, and the image signal is modulated with laser light or the like. After the electric image is formed, the electrostatic image is developed with a charged toner, and a visualized toner image is formed. Then, the toner image is electrostatically transferred to a transfer material such as recording paper via an intermediate transfer member, and fixed on the recording material, whereby a required reproduced image is obtained.
In particular, there is known an image forming apparatus that employs a system in which a toner image formed on the image carrier is primarily transferred to an intermediate transfer member, and a toner image on the intermediate transfer member is secondarily transferred to a recording sheet (for example, , See Patent Document 1).

  Further, as a semiconductive belt that can be used for an intermediate transfer belt, a transfer conveyance belt, and the like, an intermediate transfer belt in which a conductive filler is dispersed in a polyimide resin excellent in mechanical properties and heat resistance has been proposed (for example, (See Patent Documents 2 and 3.)

  However, the above-mentioned ones are inferior in toner transferability due to their high hardness, and in recent years, special papers with irregularities on the surface such as colored paper and embossing have also been used. Since the followability of the toner is particularly bad, there is a problem that the transferability of the toner is extremely inferior.

  In addition, as a belt material having a multilayer structure, for example, an endless belt having a multilayer structure made of plastic, or a belt in which a polyolefin urethane layer is applied to a rubber belt surface has been proposed (see, for example, Patent Documents 4 and 5). .

  However, endless belts with a multilayer structure made of plastics have poor toner transferability due to the high hardness described above, and in recent years, special papers with irregularities on the surface such as colored paper and embossing have also been used. Therefore, since the following ability to paper is particularly bad, there is a problem that the transferability of toner is remarkably inferior. In addition, since the stress is large, the toner is easily destroyed, toner filming on the belt occurs, and the durability is inferior.

  In addition, the belt of which the polyolefin-based urethane layer, which is a thermoplastic elastomer, is applied to the rubber belt surface, because the polyolefin-based urethane is spray-coated on the rubber belt, the coating thickness varies in the surface direction, There is a drawback that the dimensional accuracy is poor. In addition, polyolefin-based urethane has a large amount of sag (deformation with time), and has a disadvantage that it adversely affects a copied image.

  Moreover, as a two-layer constitution belt using a thermosetting urethane resin, the thermosetting urethane resin of the surface layer has a JIS A hardness of 30 to 70 degrees, and the thermosetting urethane resin of the base material has a JIS A hardness of 75 degrees or more. By doing so, it is said that good transfer image quality can be obtained even on a sheet with low surface smoothness (see, for example, Patent Document 6).

  However, when the surface layer includes a thermosetting urethane resin member, micro slip occurs between the opposing image holding members, and problems such as deterioration of color registration occur. Furthermore, even if a high-hardness thermosetting urethane resin is used as the base material, the Young's modulus is lower than that of the resin material. Therefore, in order to obtain strength, it is necessary to increase the thickness of the belt. By increasing the thickness of the substrate, the deformation of the surface layer at the roll bending portion increases, and the surface layer deteriorates during long-term use, resulting in problems such as no good transfer image quality.

As a rubber 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 a resin member has been proposed. However, since the elastic belt with a reinforcing material uses insulating fibers as the reinforcing material, there is a problem that the resistance value variation of the conductive member is deteriorated. In addition, since the amount of the insulating fiber added cannot be increased, the elastic belt with a reinforcing material may cause a problem of color misregistration due to creep deformation of the belt material over time (for example, Patent Document 7). , 8 and 9).
JP-A-62-206567 JP-A-5-77252 Japanese Patent Laid-Open No. 10-63115 Japanese Patent Laid-Open No. 11-24428 Japanese Patent Laid-Open No. 11-45015 JP 2001-282009 A Japanese Patent Laid-Open No. 9-305038 Japanese Patent No. 3445082 Japanese Patent No. 3517544

An object of the present invention is to achieve the following object in consideration of the problems in the prior art.
It is an object of the present invention to suppress the occurrence of color slip and suppress the deterioration of color registration. Another object of the present invention is to provide an image forming apparatus including the semiconductive belt.

Means for solving the above-described problems can be achieved by the present invention described below.
That is, the present invention
<1> A semiconductive belt comprising a base material and a surface layer provided on the base material, containing conductive organic fibers, and having a durometer hardness of A30 to A70.

  <2> The semiconductive belt according to <1>, wherein the conductive organic fiber has a diameter of 10 to 50 μm.

<3> The semiconductive belt according to <1> or <2>, wherein the surface layer includes the conductive organic fiber as an aggregate, and an inter-fiber distance of the aggregate is 100 to 1000 μm.

<4> The semiconductive belt according to any one of <1> to <3>, wherein the conductive organic fiber has a volume resistivity of 1 × 10 ³ Ωcm to 1 × 10 ⁹ Ωcm.

  <5> The semiconductive belt according to any one of <1> to <4>, wherein the surface layer further contains a lubricating component.

  <6> The semiconductive belt according to <5>, wherein the lubricating component is a compound containing a fluorine atom.

  <7> The semiconductive belt according to any one of <1> to <6>, wherein the surface layer contains a thermosetting urethane resin.

  <8> The semiconductive belt according to any one of <1> to <7>, wherein the surface layer has a thickness of 0.1 to 0.5 mm.

  <9> The semiconductive belt according to any one of <1> to <8>, wherein the base material has a Young's modulus of 1000 MPa to 8000 MPa.

  <10> The semiconductive belt according to <9>, wherein the base material contains a polyimide resin.

  <11> An image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming a latent image on the surface of the image carrier, and developing the latent image with toner to form a toner image Developing means, transfer means for transferring the toner image to a recording medium, and fixing means for heat-fixing the toner image to the recording medium. The transfer means is provided on a base material and the base material. And a semiconductive belt comprising a conductive organic fiber and a surface layer having a durometer hardness of A30 to A70.

  <12> The image forming apparatus according to <11>, wherein the surface layer has a thickness of 0.1 to 0.5 mm.

<13> The image forming apparatus according to <11> or <12>, wherein a shape factor SF of the toner defined by the following formula (1) is 100 to 140.
Formula (1)
SF = [(maximum length of toner particles) ² ] / [(projected area of toner particles) × π × 1/4 × 100]

  According to the present invention, the occurrence of microslip is small, and deterioration of color registration can be suppressed. In addition, the present invention can provide an image forming apparatus including the semiconductive belt.

[Semiconductive belt]
The semiconductive belt of the present invention will be described with reference to FIG. As shown in FIG. 1, a semiconductive belt 1 of the present invention is suitably used in an electrophotographic image forming apparatus, and is a base 3 and a surface layer provided on the outer peripheral surface of the base 3. And surface layer 2 having a durometer hardness of A30 to A70. Here, FIG. 1 is a sectional view showing an example of the configuration of the semiconductive belt of the present invention.

Furthermore, by making the semiconductive belt of the present invention a two-layer structure composed of the surface layer 2 and the base material 3, it is possible to satisfy the balance between flexibility and rigidity that cannot be obtained with a single material configuration. it can.
In addition to the surface layer 2 and the base material 3, the semiconductive belt of the present invention is provided with, for example, an elastic layer between the surface layer 2 and the base material 3, and a surface protective layer on the outer peripheral surface of the surface layer. Further, it is possible to further increase the number of layers as long as the effects of the present invention are not impaired.

<Surface layer>
The surface layer contains conductive organic fibers and has a durometer hardness of A30 to A70. Specifically, the surface layer includes, for example, conductive organic fibers and a resin material. Moreover, you may contain the lubricity component and other additive which make a surface layer express lubricity as needed.

By containing at least conductive organic fibers as the material of the surface layer, the surface layer can suppress deformation in the direction along the surface, thereby preventing the occurrence of microslip. In addition, by setting the durometer hardness within the above range, it is excellent in forming a nip shape at the transfer part, and there are image quality defects such as line image dropout (holocharacter), toner scattering (blur), and color shift. Remarkably reduced.
In addition, by making the durometer hardness of the surface layer within the above range, the followability to special paper with irregularities on the surface of colored paper and embossing etc. will improve, so irregularities will be added to the surface of colored paper and embossing etc. In addition, the transfer property of the special paper toner can be improved, and a high-quality transfer image quality can be stably obtained.

  Further, as will be described later, when a thermosetting elastomer composition is used as the resin material, a surface layer that is less likely to be deformed with time and excellent in durability can be formed. Further, by dispersing a lubricating component that expresses lubricating properties, toner filming on the belt is less likely to occur, and the problem of sticking (stacking) with the opposing image carrier is less likely to occur, so the durability is further improved. A surface layer can be formed.

(Conductive organic fiber)
The conductive organic fiber is used as a filler for the surface layer. As the conductive organic fibers, resin-based short fibers are preferably used. Examples of the resin-based short fibers include cotton, hemp, silk, rayon, acetate, nylon, acrylic, vinylon, vinylidene, polyester, polystyrene, polypropylene, Examples thereof include resin-based conductive organic fibers such as aramid.
Specific examples of the conductive organic fiber include aromatic polyamide fibers because they have a large reinforcing effect when added to a resin material. Specific examples of the para-type aromatic polyamide fiber include copolyparaphenylene • 3,4′-oxydiphenylene • terephthalamide fiber (“Technola” manufactured by Teijin Techno Products Co., Ltd.). Examples of the meta-type aromatic polyamide fiber include polymetaphenylene isophthalamide fiber (“Conex” manufactured by Teijin Techno Products Co., Ltd.).
In order to impart conductivity, the conductive organic fibers are kneaded and dispersed with metal oxide particles, metal filler, conductive carbon black (furnace black, acetylene black, ketjen black, etc.) and the like. Also good.

  10-40 mass parts is preferable with respect to 100 mass parts of resin, and, as for the compounding quantity with respect to resin (matrix resin which comprises a surface layer: resin material) of the said conductive organic fiber, 20-30 mass parts is still more preferable. Here, when the conductive organic fiber is less than 10 parts by mass, sufficient physical properties are not obtained even when combined with other reinforcing agents, and when it exceeds 50 parts by mass, the workability is deteriorated and a problem that molding cannot be performed may occur.

  10-50 micrometers is preferable and, as for the diameter (maximum diameter) of the said conductive organic fiber, 15-40 micrometers is more preferable. When the diameter is less than 10 μm, the reinforcing effect may be small. When the diameter exceeds 50 μm, it is difficult to disperse the conductive organic fibers, or the surface of the resin material is deteriorated. There is.

“Conductivity” of the conductive organic fiber means a volume resistivity in the range of 1 × 10 ³ to 1 × 10 ⁹ Ωcm.
The volume resistivity of the conductive organic fiber is equal to the resistance value of the belt or slightly lower in consideration of the resistance at the contact interface, which is preferable for leveling the electric characteristics of the belt, and the volume resistivity is 1 × It is preferably in the range of 10 ³ to 1 × 10 ⁹ Ωcm. A more preferable range of volume resistivity is 1 × 10 ⁴ to 1 × 10 ⁸ Ωcm.
When the volume resistivity is less than 1 × 10 ³ Ωcm, when the conductive material is dispersed in the fiber, the concentration of the conductive material becomes excessive, and it may be difficult to produce the yarn. On the other hand, when the volume resistivity exceeds 1 × 10 ⁹ Ωcm, the resistance value in the fiber axis direction becomes too high, and the conductivity may be poor.

  The form of the conductive organic fiber is not particularly limited, such as long fiber and spun yarn, and may be used in the form of blended yarn (for example, blended yarn of para-type aromatic polyamide fiber and meta-type aromatic polyamide fiber).

The conductive organic fiber is not limited to a form in which short fibers are dispersed and reinforced in the surface layer, but may be in a form in which the surface layer is reinforced by an aggregate of fibers.
Examples of fiber aggregates include woven fabrics, nonwoven fabrics, and spirally wound cords made of fibers.
As a method for incorporating a fiber aggregate into the surface layer, for example, a fiber aggregate is installed on the outer peripheral surface of the substrate (or a cord is wound), and then a resin material (or a precursor thereof) is formed on the substrate surface. To do.

  In the fiber assembly, the intermediate transfer belt is always subjected to a high load in the moving direction (circumferential direction) and is stretched. Therefore, in the moving direction of the belt, fibers having higher modulus and lower elongation (for example, para-type aromatics). It is preferable to weave (polyamide).

The distance between the fibers is preferably 100 to 1000 μm, and more preferably 200 to 800 μm. When the thickness is less than 100 μm, the resistance uniformity of the resin material may be deteriorated, and when it exceeds 1000 μm, the reinforcing effect may be small.
The interfiber distance is the distance between the outer surface of the fibers adjacent to each other and the outer surface of the fibers.

  The preferred properties of the above fibers, nonwoven fabrics, etc. are shown below. The fiber diameter (maximum diameter) is preferably 10 to 50 μm, and more preferably 15 to 40 μm. Moreover, in the case of a nonwoven fabric, the distance between fibers is preferably 100 to 1000 μm, and more preferably 200 to 800 μm.

(Resin material)
Examples of the resin material that can be used for the surface layer include thermosetting elastomers. As this thermosetting elastomer, any resin having a urethane bond or an ester bond in the repeating unit can be used. Among these, a thermosetting polyurethane resin is preferable from the viewpoint of flexibility of the obtained semiconductive belt surface layer.

  The thermosetting polyurethane resin can be obtained by reacting a polyol such as linear polyester, polyether or polyesteramide with an isocyanate such as diisocyanate with a chain extender or a crosslinking agent.

(Lubricity component)
Although it does not specifically limit as a lubricity component, The compound containing a fluorine atom is mentioned. Specific examples include a monomer obtained by grafting fluorine at the terminal (hereinafter referred to as a lubricity-imparting monomer) and a lubricating filler (for example, a fluorinated compound or a resin powder).

-Lubricity imparting monomer-
The lubricity-imparting monomer is not particularly limited, and examples thereof include an acrylic monomer (Soken Kagaku Co., Ltd. Chemitry LF-700) obtained by grafting fluorine at the terminal.

  The addition amount of the lubricity-imparting monomer is 10 to 60 parts by mass, preferably 20 to 50 parts by mass with respect to 100 parts by mass of the resin material. When the addition amount of the lubricity-imparting monomer is less than 10 parts by mass, the effect of lubricity may not be exhibited. When 60 parts by mass or more is added, the thermosetting elastomer that forms the surface layer is soft. As a result, the above-described micro slip problem may occur.

-Lubricating filler-
Examples of the lubricating filler include polyvinyl fluoride, PVDF, tetrafluoroethylene (TFE) resin, chlorotrifluoroethylene (CTFE) resin, ETFE, CTFE-ethylene copolymer, and PFA (TFE-perfluoroalkyl vinyl ether copolymer). ), FEP (TFE-hexafluoropropylene (HFP) copolymer), EPE (TFE-HFP-perfluoroalkyl vinyl ether copolymer), etc. It is done.

  As the fluororesin, a powder having an average particle diameter of 1 μm or less is preferably used. When the average particle diameter is larger than 1 μm, the belt surface becomes rough and the transferability deteriorates. Moreover, the addition amount of a lubricous filler is 5-80 mass parts with respect to 100 mass parts of resin materials, Preferably, it is 10-60 mass parts. When the addition amount of the lubricating filler is less than 5 parts by mass, the effect of the lubricating filler may not be exhibited. When 80 parts by mass or more is added, for example, a thermosetting elastomer that forms the surface layer In some cases, it becomes hard and it becomes impossible to follow a special paper with uneven surfaces such as colored paper or embossing.

(Surface roughness of surface layer)
Furthermore, the surface roughness (ten-point average roughness) Rz of the surface layer 2 may be appropriately selected, but is preferably 1.5 μm or more and 9.0 μm or less. If it is less than 1.5 μm, there is a concern that it may be in close contact with a member such as an image carrier, and if it exceeds 9.0 μm, toner that is an image material adheres, and image quality deterioration such as uneven halftone may occur. There is.
The surface roughness (ten-point average roughness) Rz was measured according to JISB0601 (1994) using a surface roughness shape measuring instrument (Surfcom Co., Ltd. 1400A series manufactured by Tokyo Seimitsu). Specifically, the measurement was performed under the conditions of a measurement length of 2.5 mm, a cutoff wavelength of 0.8 mm, and a measurement speed of 0.60 mm / s.

(Hardness of surface layer)
The durometer hardness of the surface layer is a durometer hardness according to JIS K7215 (1986), and is A30 to A70, preferably A40 to A60. Since the A layer hardness of the surface layer material is A30 to A70, the followability to special paper with irregularities on the surface such as colored paper or embossing is improved, so the toner transferability can be improved. When the surface layer has an A hardness exceeding A70, the followability to a special paper with irregularities on the surface such as colored paper or embossing is deteriorated, so that the toner transferability may be deteriorated. If the A hardness is less than A30, there may be a problem that the surface layer is easily damaged by a metal cleaning member, paper dust (calcium carbonate contained in the paper), or the like.
The durometer hardness of the surface layer was measured in accordance with JIS K7215 by laminating a sheet-shaped surface layer to a thickness of 6 mm.

<Base material>
As the material of the belt base material, it is preferable to use a resin material having a Young's modulus of 1000 MPa or more, more preferably 1500 MPa or more, and further preferably 2000 MPa or more to satisfy the mechanical properties. If a resin material with a Young's modulus of 1000 MPa or more is used as the base material, the amount of belt displacement due to disturbance (load fluctuation) during belt driving decreases, belt deformation due to stress during driving decreases, and good image quality is achieved. It can be obtained stably. In addition, the upper limit of Young's modulus for manufacturing is about 8000 MPa. With this configuration, the belt can satisfy the balance between flexibility and rigidity, which cannot be obtained more effectively with a single material configuration.

  Examples of the resin material used for such a base material include polyimide resin, polyamideimide resin, fluorine resin, vinyl chloride vinyl acetate copolymer, polycarbonate resin, polyethylene terephthalate resin, vinyl chloride resin, ABS resin, and polymethyl. Examples thereof include a methacrylate resin and a polybutylene terephthalate resin. These may be used alone or in combination of two or more. Among these, a polyimide resin is preferably used because it is excellent in both strength and bending fatigue.

  Examples of the polyimide resin include those obtained by reacting an aromatic tetracarboxylic acid component and an aromatic diamine component in an organic polar solvent.

  As aromatic tetracarboxylic acid components, pyromellitic acid, naphthalene-1,4,5,8-tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, 2,3,5,6-biphenyl Tetracarboxylic acid, 2,2 ′, 3,3′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-diphenylethertetracarboxylic acid Acid, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid, 3,3 ′, 4,4′-azobenzenetetracarboxylic acid bis (2 , 3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenyl) methane, β, β-bis (3,4-dicarboxyphenyl) propane, β, β-bis (3,4-dicarbo) Shifeniru) has hexa off Oro propane or a mixture of these tetracarboxylic acids.

  The aromatic diamine component is not particularly limited, and m-phenyldiamine, p-phenyldiamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminochlorobenzene, m-xylylenediamine , P-xylylenediamine, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4′-diaminonaphthalenediphenyl, benzidine, 3,3-dimethylbenzidine, 3,3 '-Dimethoxybenzidine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether (oxy-p, p'-dianiline; ODA), 4,4'-diaminodiphenyl sulfide, 3, 3'-diaminobenzophenone, 4,4'-diaminophenyl sulfone, 4,4'-diaminoa Benzene, 4,4'-diaminodiphenylmethane, beta, beta-bis (4-amine phenyl) propane.

  Examples of the organic polar solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphortriamide and the like. These organic polar solvents can be mixed with phenols such as cresol, phenol and xylenol, and hydrocarbons such as hexane, benzene and toluene, if necessary. These solvents are also used alone or as a mixture of two or more.

(Conductive agent)
To the resin composition used for these surface layers and base materials, a conductive agent imparting electron conductivity or a conductive agent imparting ionic conductivity may be added, if necessary, in combination of one type or two or more types. Is preferred.

  As an electron conductive conductive agent, metal or alloy such as carbon black, graphite, aluminum, nickel, copper alloy, tin oxide, zinc oxide, kalim titanate, tin oxide-indium oxide or tin oxide-antimony oxide composite oxide, etc. Examples of the metal oxide can be given.

  Examples of the ion conductive conductive agent include sulfonates and ammonia salts, and various surfactants such as cationic, anionic, and nonionic surfactants. Furthermore, there is a method of blending conductive polymers. Examples of conductive polymers include various (for example, styrene) copolymers with (meth) acrylates that bind a quaternary ammonium base to a carboxyl group, and a quaternary ammonium base. Polymers that bind quaternary ammonium bases, such as a copolymer of maleimide and methacrylate, which binds to styrene, polymers that bind alkali metal salts of sulfonic acids such as sodium polysulfonate, hydrophilic units of at least alkyl oxide in the molecular chain For example, polyethylene oxide, polyethylene glycol-based polyamide copolymer, polyethylene oxy-epichlorohydrin copolymer polyether amide imide, block type polymer having polyether as a main segment, and polyaniline , Polythiophene, polyacetylene, can be mentioned polypyrrole, polyphenylene vinylene and the like, can be used These conductive Porima undoped state, or in a doped state. The above-described electrical resistance can be stably obtained by using one or two or more of the above-mentioned conductive agent, conductive polymer, or surfactant.

  As the conductive agent, good dispersion stability is obtained because of its good dispersibility in the resin composition, resistance variation of the semiconductive belt can be reduced, electric field dependency is also reduced, and transfer is further improved. It is preferable to use oxidized carbon black having a pH of 5 or lower because the electric field concentration due to voltage becomes less likely to improve the stability of electrical resistance over time.

(Oxidized carbon black of pH 5 or less)
The oxidation-treated carbon black having a pH of 5 or less can be produced by oxidizing the carbon black to impart a carboxyl group, a quinone group, a lactone group, a hydroxyl group or the like to the surface of the carbon black. 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, oxidized 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. Oxidized carbon black can also be produced by a furnace 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.

  Acidic carbon black can be produced by a contact method, but is usually produced by a closed furnace method. In the furnace method, only carbon black having a high pH and a low volatile content is usually produced, but the pH can be adjusted by performing the above-described liquid phase oxidation treatment. For this reason, in the present invention, carbon black obtained by the furnace method and adjusted to have a pH of 5 or less by post-treatment is regarded as being included in the oxidized carbon black having a pH of 5 or less.

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

  The pH of the oxidation-treated carbon black is determined by adjusting an aqueous suspension and measuring 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 content of the volatile component in the oxidized carbon black is preferably 1 to 25 parts by mass, more preferably 3 to 20 parts by mass, and still more preferably 3.5 to 15 parts by mass. When the content of the volatile component is less than 1 part by mass, the effect of the oxygen-containing functional group attached to the surface is lost, and the dispersibility in the binder resin may be reduced. On the other hand, when the content of the volatile component is more than 25 parts by mass, it may be decomposed when the oxidized carbon black is dispersed in the resin composition or adsorbed on the oxygen-containing functional group on the surface of the carbon black. The appearance of the surface layer or the substrate may be deteriorated due to an increase in the amount of water that has been discharged.

  On the other hand, the dispersion | distribution in the said resin composition can be made more favorable because content of a volatile component shall be 5-25 mass parts. The content of the volatile component can be determined from the ratio of organic volatile components (carboxyl group, hydroxyl group, quinone group, lactone group, etc.) that come out when carbon black is heated at 950 ° C. for 7 minutes.

  Here, two or more types of carbon black as the conductive agent may be contained. At that time, it is preferable that these carbon blacks have substantially different conductivity from each other, for example, those having different physical properties such as the degree of oxidation treatment, DBP oil absorption, specific surface area by BET method utilizing nitrogen adsorption, etc. Is used. Here, the DBP oil absorption refers to the amount (ml) of DBP absorbed by 100 g of carbon black. Carbon blacks with a higher DBP oil absorption form longer chain bonds.

  When two or more types of carbon blacks having different conductivity are added in this way, for example, carbon black that expresses high conductivity is preferentially added, and then carbon black with low conductivity is added to adjust the surface resistivity. It is possible to do. Even when two or more types of carbon black are contained in this way, at least one of them can be mixed and dispersed by using an oxidation-treated carbon black having a pH of 5.0 or less.

  Specifically, as the oxidation-treated carbon black, “Printex 150T” (pH 4.5, 10.0 parts by mass of volatile content) manufactured by Degussa Co., Ltd., “Special Black 350” (pH 3.5, volatile content 2) 2 parts by mass), "Special Black 100" (pH 3.3, volatile matter 2.2 parts by mass), "Special Black 250" (pH 3.1, volatile matter 2.0 parts by mass), "Special Black" 5 "(pH 3.0, volatile matter 15.0 parts by mass)," Special Black 4 "(pH 3.0, volatile matter 14.0 parts by mass)," Special Black 4A "(pH 3.0, volatile matter 14) , "Special Black 550" (pH 2.8, volatile matter 2.5 parts by mass), "Special Black 6" (pH 2.5, volatile matter 18.0 parts by mass), "Color Black" F 200 ”(pH 2.5, volatile matter 20.0 parts by mass),“ Color Black FW2 ”(pH 2.5, volatile matter 16.5 parts by mass),“ Color Black FW2V ”(pH 2.5, volatile matter 16) .5 mass parts), “MONARCH1000” (pH 2.5, volatile content 9.5 mass parts) manufactured by Cabot Corporation, “MONARCH 1300” (pH 2.5, 9.5 mass parts volatile content) manufactured by Cabot Corporation, “manufactured by Cabot Corporation” “MONARCH1400” (pH 2.5, volatile matter 9.0 parts by mass), “MOGUL-L” (pH 2.5, volatile matter 5.0 parts by mass), “REGAL400R” (pH 4.0, volatile matter 3.5) Mass parts) and the like.

  Oxidized carbon black has better dispersibility in the resin composition due to the effect of oxygen-containing functional groups present on the surface as described above compared to general carbon black. It is preferable to increase it. Thereby, since the amount of carbon black in the semiconductive belt increases, the effect of using the oxidized carbon black that can suppress the in-plane variation of the electrical resistance value can be maximized. .

It is preferable that the content of the oxidized carbon black with respect to the surface layer and the base material is 10 to 30 parts by mass because the effect of the oxidized carbon black can be exhibited, such as suppressing in-plane variation of the surface resistivity of the semiconductive belt. .
If the oxidation-treated carbon black is less than 10 parts by mass, the uniformity of electrical resistance is lowered, and the in-plane unevenness of the surface resistivity and the electric field dependency may increase. On the other hand, if the content of the oxidized carbon black exceeds 30 parts by mass, it may be difficult to obtain a desired resistance value. Furthermore, it is more preferable to contain 18 to 30 parts by mass of oxidized carbon black. By containing 18 to 30 parts by mass of oxidized carbon black, the effect can be maximized, and the in-plane unevenness of the surface resistivity and the electric field dependency can be remarkably improved.

<Volume resistivity>
The volume resistivity of the surface layer and the base material in the semiconductive belt of the present invention is preferably 1 × 10 ⁸ to 1 × 10 ¹³ Ωcm, more preferably 1 × 10 ⁹ to 1 × 10 ¹² Ωcm. It is.
If the volume resistivity of the surface layer and the substrate is 1 × 10 ⁸ to 1 × 10 ¹³ Ωcm, the toner is surrounded around the image by the electrostatic repulsion between the toners and the force of the fringe electric field near the image edge. The problem of scattering (blur) is less likely to occur. In addition, within the above range, the volume resistivity of the semiconductive belt (especially when applied to an intermediate transfer member) is in a range where the charged charge is appropriately attenuated. Image formation can be performed continuously.

  Here, the volume resistivity can be measured according to JIS K 6911 (1995) using a circular electrode (for example, Hiresta UPMCP-450 UR probe manufactured by Dia Instruments Co., Ltd.). A method for measuring the volume resistivity will be described with reference to the drawings.

  FIG. 2 is a schematic plan view (a) and a schematic cross-sectional view (b) showing an example of a circular electrode. As shown in FIG. 2, the circular electrode includes a first voltage application electrode A ′ and a second voltage application electrode B ′. The first voltage application electrode A ′ has a cylindrical electrode part C ′ and a cylindrical shape having an inner diameter larger than the outer diameter of the cylindrical electrode part C ′ and surrounding the cylindrical electrode part C ′ at a constant interval. Ring-shaped electrode portion D ′.

The semiconductive belt 1 is sandwiched between the cylindrical electrode portion C ′ and ring-shaped electrode portion D ′ and the second voltage application electrode B ′ in the first voltage application electrode A ′, and the first voltage application electrode A ′. The current I (A) that flows when the voltage V (V) is applied between the cylindrical electrode portion C ′ and the second voltage application electrode B ′ is measured, and the volume resistance of the semiconductive belt 1 is calculated by the following equation. The rate ρv (Ωcm) can be calculated. Here, in the following formula, t (cm) indicates the thickness of the semiconductive belt 1.
Formula: ρv = 19.6 × (V / I) × t

As the thickness of the belt increases, the amount of deformation of the outer surface of the belt at a belt bending portion such as a drive system roll increases, and 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. The thickness of the semiconductive belt of the present invention is preferably 0.05 to 0.5 mm in total thickness, more preferably 0.1 to 0.4 mm, and 0.15 to 0.3 mm. More preferably.
When the thickness of the belt is less than 0.05 mm, there may be a problem that the belt circumferential length changes due to belt tension. Further, when the belt thickness exceeds 0.5 mm, the belt surface is greatly deformed at the roll bending portion, so that a problem such as a crack on the surface may occur.

  The thickness of the surface layer is preferably 10 to 90% of the total belt thickness, and more preferably 30 to 70%. Within the above range, the pressing force concentrated on the toner on the semiconductive belt is dispersed without being affected by the resin composition of the substrate. For this reason, the toner does not aggregate, and the followability to special paper with irregularities on the surface of colored paper or embossing is improved, so the transferability of special paper toner with irregularities on the surface of colored paper or embossing etc. Can be improved. Further, when the Young's modulus of the resin composition of the base material is as high as 1000 MPa or more, the mechanical properties as a semiconductive belt can be satisfied.

  The semiconductive belt of the present invention can be used as an intermediate transfer belt and a paper conveying belt used in an image forming apparatus such as an electrophotographic copying machine or a laser printer.

  The shape of the semiconductive belt of the present invention is endless, and can be formed by an appropriate connection method such as an adhesive method using an adhesive at the film end or a seamless belt. The seamless belt has an advantage that an arbitrary portion can be set as the rotation start position without any change in the thickness of the joint, and a control mechanism for the rotation start position can be omitted.

  The base material and the surface layer can be formed by forming each layer into a sheet shape by an extrusion molding method, and then laminating it on a metal core and heat-treating it to form a two-layer belt, A base material can be formed in a belt shape, laminated on a metal core, and a surface layer can be formed thereon. Also, a two-layer belt can be formed by simultaneous molding while laminating the surface layer and the substrate.

[Image forming apparatus]
The image forming apparatus of the present invention is not particularly limited as long as it is an intermediate transfer body type image forming apparatus. For example, a normal monocolor image forming apparatus that contains only a single color toner in a developing device, or a color image in which a toner image held on an image holding body such as a photosensitive drum is repeatedly subjected to primary transfer sequentially to an intermediate transfer body Any of a forming apparatus, a tandem type color image forming apparatus in which a plurality of image carriers having developing units for respective colors are arranged in series on an intermediate transfer member may be used.

  The first embodiment of the image forming apparatus of the present invention uses the above-described semiconductive belt of the present invention as an intermediate transfer belt, and uses a toner image held on an image carrier such as a photosensitive drum as an intermediate transfer member. This is a color image forming apparatus in which primary transfer is sequentially repeated. A second aspect of the image forming apparatus of the present invention is a tandem type color image forming apparatus in which a plurality of image holding members each having a developing device for each color are arranged in series on an intermediate transfer member.

  FIG. 3 shows an example of a schematic diagram of a color image forming apparatus using the semiconductive belt of the present invention as an intermediate transfer belt and repeating primary transfer sequentially. FIG. 3 is a schematic diagram for explaining a main part of an image forming apparatus to which the present invention is applied. The image forming apparatus includes a photosensitive drum 21 as an image holding member, an intermediate transfer belt 22 as an intermediate transfer member, a bias roller 23 (second transfer unit) as a transfer electrode, and a sheet for supplying recording paper as a transfer medium. Tray 24, developing device 25 using Bk (black) toner, developing device 26 using Y (yellow) toner, developing device 27 using M (magenta) toner, developing device 28 using C (cyan) toner, intermediate transfer body cleaner 29, peeling Claw 33, belt rollers 41, 43 and 44, backup roller 42, conductive roller 45 (first transfer means), electrode roller 46, cleaning blade 51, recording paper 61, pickup roller 62, and feed roller 63. Become.

  In FIG. 3, 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 21 by image writing means such as a laser writing device. The electrostatic latent image is developed with toner by the black developing device 25 to form a visualized toner image T. The toner image T reaches the primary transfer portion where the conductive roller 45 (first transfer means) is disposed by the rotation of the photosensitive drum 21, and an electric field having a reverse polarity is applied to the toner image T from the conductive roller 45. Thus, the toner image T is primarily transferred by the rotation of the intermediate transfer belt 22 in the direction of arrow B while being electrostatically attracted to the intermediate transfer belt 22.

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 intermediate transfer belt 22 to form a multiple toner image.
The multiple toner images transferred to the intermediate transfer belt 22 reach the secondary transfer portion where the bias roller 23 (second transfer means) is installed as the intermediate transfer belt 22 rotates. The secondary transfer unit includes a bias roller 23 installed on the surface side where the toner image of the intermediate transfer belt 22 is held, a backup roller 42 disposed so as to face the bias roller 23 from the back side of the intermediate transfer belt 22, and It is composed of an electrode roller 46 that rotates in pressure contact with the backup roller 42.

  The recording paper 61 is picked up one by one from the recording paper bundle stored in the paper tray 24 by the pickup roller 62, and is fed at a predetermined timing between the intermediate transfer belt 22 and the bias roller 23 of the secondary transfer portion by the feed roller 63. It is sent by. The toner image held on the intermediate transfer belt 22 is transferred to the fed recording paper 61 by the pressure contact conveyance by the bias roller 23 and the backup roller 42 and the rotation of the intermediate transfer belt 22.

  The recording paper 61 onto which the toner image has been transferred is peeled from the intermediate transfer belt 22 by operating the peeling claw 33 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 by heat treatment to be a permanent image. The intermediate transfer belt 22 having completed the transfer of the multiple toner image to the recording paper 61 is prepared for the next transfer by removing residual toner by an intermediate transfer body cleaner 29 provided downstream of the secondary transfer portion. The bias roller 23 is attached so that a cleaning blade 51 made of polyurethane or the like is always in contact therewith, and foreign matters such as toner particles and paper dust adhered by transfer are removed.

  In the case of transfer of a single color image, the primary transferred toner image T is immediately secondarily transferred and conveyed to the fixing device. Therefore, the rotation of the intermediate transfer belt 22 and the photosensitive drum 21 is synchronized so that the toner images of the respective colors do not shift so as to match exactly. In the secondary transfer portion, an output pressure (transfer voltage) having the same polarity as the polarity of the toner image is applied to the electrode roller 46 that is in pressure contact with the backup roller 42 that is disposed opposite to the bias roller 23 via the intermediate transfer belt 22. Then, the toner image is transferred to the recording paper 61 by electrostatic repulsion. With the image forming apparatus having the above-described configuration, high-quality transfer image quality can be stably obtained.

  Further, the second embodiment of the image forming apparatus of the present invention includes an intermediate transfer belt which is the semiconductive belt of the present invention, and includes, for example, a developing device 85 of four colors (black, yellow, magenta, cyan). Further, the tandem color image forming apparatus in which the photoreceptors 79 for the respective colors are arranged on an intermediate transfer body (intermediate transfer belt) 86.

FIG. 4 is an example of a schematic diagram for explaining a main part of a tandem image forming apparatus to which the present invention is applied. By providing the intermediate transfer belt of the present invention, a high-quality transfer image can be obtained.
Specifically, as shown in FIG. 4, a charging roll 83 (charging device) that uniformly charges the surface of the photoreceptor 79, and a laser generator 78 (exposure device) that exposes the surface of the photoreceptor 79 to form an electrostatic latent image. ), A latent image formed on the surface of the photoreceptor 79 is developed using a developer, and a developer 85 (developing device) that forms a toner image, and a photoreceptor cleaner that removes toner, dust, and the like attached to the photoreceptor. A toner 84 (cleaning device), a fixing roll 72 for fixing the toner image on the transfer material, and the like can be optionally provided by a known method as necessary.

  More specifically, a toner image is first formed for each developing unit, and after the surface of the photoreceptor 79 rotating counterclockwise by the charging roll 83 is uniformly charged, a laser generator 78 (exposure device) is formed. ) To form a latent image on the surface of the photosensitive member 79 charged by the above, and then developing the latent image with a developer supplied from the developing device 85 to form a toner image. The primary transfer roll 80 and the photosensitive member The toner image conveyed to the press-contact portion with 79 is transferred onto the outer peripheral surface of the intermediate transfer belt 86 that rotates clockwise. The photosensitive member 79 after the toner image has been transferred is cleaned of toner, dust and the like adhering to the surface thereof by a photosensitive member cleaner 84 to prepare for the formation of the next toner image.

  The toner image developed for each color developing unit is sequentially superimposed on the outer peripheral surface of the intermediate transfer member 86 so as to correspond to the image information, and is conveyed to the secondary transfer unit by the secondary transfer roll 75. The image is transferred from the sheet tray 77 to the surface of the recording sheet conveyed via the sheet path 76. The recording paper on which the toner image has been transferred is further fixed by being heated by pressure when passing through the pressure contact portion of a pair of fixing rolls 72 constituting the fixing portion, and after the image is formed on the surface of the recording medium. Then, it is discharged out of the image forming apparatus. Even in a tandem image forming apparatus having such a configuration, high-quality transfer image quality can be stably obtained.

  The image forming apparatus using the semiconductive belt of the present invention as an intermediate transfer belt has been described above. However, the same effect can be obtained in an image forming apparatus using the semiconductive belt of the present invention as a paper conveying belt. It is done.

  Further, when the semiconductive belt of the present invention is used by being incorporated as an intermediate transfer belt or a paper conveying belt in the image forming apparatus, it is preferable to use a spherical toner as the toner. By using spherical toner as the toner, the material that constitutes the transfer surface has a low durometer hardness and is difficult to deform along the surface, so there is no image quality defect (holo character, blur, color registration). Quality transfer image quality can be obtained.

  However, the spherical toner means that the shape factor SF is 100 to 140. The shape factor is preferably 100 to 130, more preferably 100 to 120. When the shape factor SF 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 SF is a factor defined by the following equation.
SF = (maximum length of toner particles) ² / (projected area of toner particles) × (π / 4) × 100
The maximum length of toner particles and the projected area of the toner particles are measured using a video of an optical microscope image of 100 toners dispersed on a slide glass using a Luzex image analyzer (manufactured by Nireco Corporation, FT). This was carried out by taking the image into a Luzex image analyzer through a camera and processing the image.

  The spherical toner contains at least a binder resin and a colorant. The volume average particle diameter of the spherical toner is preferably 2 to 12 μm, more preferably 3 to 9 μm.

  Binder resins 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 methyl acrylate. , Α-methylene aliphatic monocarboxylic esters such as ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, vinyl Homopolymers and copolymers of vinyl ethers such as methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone can be exemplified, Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax, and the like can also be mentioned.

  Coloring agents 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 is a typical 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 particles. Typical examples of the release agent include low molecular weight polyethylene, low molecular weight 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 particles, small-diameter inorganic 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. These inorganic or organic particles may be used in combination. As these other inorganic 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 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 a spherical toner, emulsion polymerization aggregation method, polymerizable monomer to obtain a binder resin, colorant, if necessary, release agent, 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.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Example 1>
-Formation of base material-
(Preparation of polyamic acid solution (A))
As a tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) are combined in a ratio of 2: 1 to obtain a diamine. As a component, N-methyl-2-pyrrolidone (NMP) solution of polyamic acid composed of 4,4′-diaminodiphenyl ether (DDE) (solid content: 20 parts by mass) and dried oxidized carbon black (SPECIAL BLACK4 (manufactured by Degussa) , PH 3.0, volatile content: 14.0%) with respect to 100 parts by mass of polyimide resin solids, and added to 24 parts by mass, using a collision type disperser (Geanus PY made by Seanas), pressure 200 MPa set, it collides with a minimum area of 1.4 mm ² after two divided, by passing 5 times a path divided into two again, mixed Te to obtain a carbon black-containing polyamic acid solution of the base material for the (A).

(Preparation of substrate A)
The polyamic acid solution containing carbon black (A) is applied to the inner surface of the cylindrical mold to a thickness of 0.4 mm via a dispenser, rotated at 1500 rpm for 15 minutes to form a spread layer having a uniform thickness, and then rotated at 250 rpm. Then, hot air at 60 ° C. was applied for 30 minutes from the outside of the mold, and then heated at 150 ° C. for 60 minutes to remove the solvent. Thereafter, the cylindrical mold was returned to room temperature, the polyamic acid molded product was peeled off from the cylindrical mold, and the metal core was coated. This was heated up to 360 ° C. at a rate of 2 ° C./min and further heated at 360 ° C. for 30 minutes to remove the solvent, remove the dehydrated ring-closing water, and complete the imide conversion reaction. Thereafter, the temperature was returned to room temperature, and the resin was peeled from the metal core to obtain a target polyimide film. The thickness of the film was 0.08 mm. The Young's modulus of this resin belt was 2500 MPa, and the volume resistivity at an applied voltage of 100 V was 5 × 10 ¹⁰ Ωcm 2.

-Young's modulus-
The Young's modulus of the substrate in the present invention was measured using FA1015A manufactured by Aiko Engineering Co., Ltd. in accordance with JIS K 7127 (1999). The measurement is performed by performing a tensile test under the condition of a test speed of 50 mm / min using a sample obtained by cutting the substrate into 5 mm × 40 mm, drawing a tangent line to the curve of the initial strain region of the obtained stress / strain curve, Obtained from the slope.

-Volume resistivity-
As described above, the volume resistivity was measured using a circular electrode (Hiresta UPMCP-450 type UR probe manufactured by Dia Instruments Co., Ltd.) in a 22 ° C./55% RH environment. A voltage of 100 (V) was applied between the cylindrical electrode portion C ′ and the second voltage application electrode B ′ in one voltage application electrode A ′, and the current value after 10 seconds was obtained.

(Formation of conductive organic fiber (A))
As a conductive agent, 100 parts by mass of copolyparaphenylene / 3,4′-oxydiphenylene / terephthalamide resin is mixed with 15 parts by mass of Ketchen Black EC manufactured by Lion Azo Co., Ltd. 3,4′-oxydiphenylene terephthalamide fiber was obtained. This conductive organic fiber had a diameter of 30 μm and a volume resistivity of 1 × 10 ⁴ Ωcm.

(Preparation of surface layer material (A))
As the material for the surface layer, 100 parts by mass of TC-551 (manufactured by Nippon Polyurethane Industry Co., Ltd.) is used as the isocyanate prepolymer, and 93 parts by mass of ON-D56 (manufactured by Nippon Polyurethane Industry Co., Ltd.) is used as the polyol. 15 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Co., Ltd.) as an agent, and Chemitry LF-700 (manufactured by Soken Kagaku Co., Ltd.) as a component imparting lubricity 50 parts by mass, mixed with 15 parts by mass of conductive copolyparaphenylene-3,4′-oxydiphenylene-terephthalamide fiber (conductive organic fiber (A)) cut to a length of 0.6 mm, The layer material (A) was adjusted.

(Formation of a two-layer belt)
The above-mentioned base material A is coated on a cylindrical mold, the surface layer material (A) is applied on the outer surface, and heated at a temperature of 80 ° C. for 120 minutes to thermoset the surface layer. The urethane layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.33 mm. The thickness of each layer of this belt was 0.25 mm for the surface layer and 0.08 mm for the base material. The material constituting the surface layer of this belt had a volume resistivity of 9 × 10 ¹⁰ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A45.

−Durometer hardness−
The durometer hardness of the surface layer is based on JIS K 7215 (1986), and only the surface layer is laminated to a thickness of 6 mm, using a durometer type A (manufactured by Kobunshi Keiki Co., Ltd .: ASKER A type). Was measured.

<Example 2>
(Formation of conductive organic fiber (B))
To 100 parts by mass of copolyparaphenylene, 3,4'-oxydiphenylene, terephthalamide resin, 12 parts by mass of Ketchen Black EC manufactured by Lion Azo Co., Ltd. was kneaded as a conductive agent. 3,4′-oxydiphenylene terephthalamide fiber was obtained. This conductive organic fiber had a diameter of 30 μm and a volume resistivity of 1 × 10 ⁸ Ωcm.

(Substrate & surface layer material)
The same material as in Example 1 was used as the base material. The material of the surface layer is composed of 100 parts by mass of MC-B86 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate prepolymer and 277 parts by mass of ON-D55 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a polyol. 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) as an agent, and Chemtry LF-700 (manufactured by Soken Kagaku Co., Ltd.) as a component imparting lubricity 35 parts by mass was mixed to prepare the surface layer material (B).

(Formation of a two-layer belt)
A cylindrical mold is coated with the above-mentioned base material A, and conductive copolyparaphenylene / 3,4′-oxydiphenylene / terephthalamide fiber (conductive organic fiber (B)) is formed at a distance of 500 μm. A nonwoven fabric woven into a tubular weave was laminated (corresponding to 20 parts by mass per 100 parts by mass of resin).
Apply the surface layer material (B) coating liquid while impregnating the conductive organic fiber (B), heat at a temperature of 80 ° C. for 120 minutes to cure the thermosetting urethane layer of the surface layer, and have an inner diameter of 168 mm A belt having a two-layer structure having a width of 350 mm and a thickness of 0.45 mm was obtained. The thickness of each layer of this belt was a surface layer of 0.37 mm and a base material of 0.08 mm. The material constituting the surface layer had a volume resistivity of 9 × 10 ¹¹ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A30.

<Example 3>
-Formation of base material-
(Preparation of polyamic acid solution (B))
N-methyl-2-pyrrolidone (NMP) solution of polyamic acid composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-diaminodiphenyl ether (DDE) (manufactured by Ube Industries) Euvanis A (solid content: 20 parts by mass) was dried with oxidized carbon black (SPECIAL BLACK4 (Degussa, pH 3.0, volatile content: 14.0%) with respect to 100 parts by mass of polyimide resin solids. Adding to 26 parts by mass, using a collision type disperser (GeanusPY made by Seanas), setting the pressure to 200 MPa, colliding with a minimum area of 1.4 mm ² after 2 divisions, and again dividing the path into 2 parts 5 times The mixture was passed through and mixed to obtain a polyamic acid solution (B) containing carbon black for a substrate.

(Preparation of base material B)
The polyamic acid solution containing carbon black (B) is applied to the inner surface of the cylindrical mold to 0.4 mm via a dispenser, rotated at 1500 rpm for 15 minutes to form a spread layer having a uniform thickness, and then rotated at 250 rpm. However, the solvent was removed by applying hot air of 60 ° C. for 30 minutes from the outside of the mold and then heating at 150 ° C. for 60 minutes. Thereafter, the cylindrical mold was returned to room temperature, the polyamic acid molded product was peeled off from the cylindrical mold, and the metal core was coated. This was heated up to 360 ° C. at a rate of 2 ° C./min and further heated at 400 ° C. for 30 minutes to remove the solvent, remove dehydrated ring-closing water, and complete the imide conversion reaction. Thereafter, the temperature was returned to room temperature, and the resin was peeled from the metal core to obtain a target polyimide film. The thickness of the film was 0.08 mm. The Young's modulus of this resin belt was 3800 MPa, and the volume resistivity at an applied voltage of 100 V was 5 × 10 ¹⁰ Ωcm.

(Formation of conductive organic fiber (C))
To 100 parts by mass of polymetaphenylene isophthalamide resin, 13 parts by mass of Ketchen Black EC manufactured by Lion Azo Co., Ltd. is kneaded as a conductive agent, and conductive copolyparaphenylene, 3,4'-oxydiphenylene terephthalate. An amide fiber was obtained. This conductive organic fiber had a diameter of 35 μm and a volume resistivity of 1 × 10 ⁷ Ωcm.

(Preparation of surface layer material (C))
As the material for the surface layer, 100 parts by mass of TC-551 (manufactured by Nippon Polyurethane Industry Co., Ltd.) is used as the isocyanate prepolymer, and 93 parts by mass of ON-D56 (manufactured by Nippon Polyurethane Industry Co., Ltd.) is used as the polyol. 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) as an agent, and fluororesin powder (Lublon L-5 having an average particle size of 0.2 μm) as a lubricant filler : Daikin Industries, Ltd.) 30 parts by mass, conductive copolyparaphenylene-3,4'-oxydiphenylene-terephthalamide fiber (conductive organic fiber (C)) cut to a length of 0.6 mm 20 The surface layer material (C) was adjusted by mixing parts by mass.

(Formation of a two-layer belt)
The above-mentioned base material B is coated on a cylindrical mold, the surface layer material (C) is applied on the outer surface, and heated at a temperature of 80 ° C. for 120 minutes to thermoset the surface layer. The urethane layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.48 mm. The thickness of each layer of this belt was a surface layer of 0.40 mm and a base material of 0.08 mm. The material constituting the surface layer of this belt had a volume resistivity of 3 × 10 ¹¹ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A65.

<Example 4>
(Substrate & surface layer material)
The same material as in Example 1 was used as the base material. As the material for the surface layer, 100 parts by mass of TC-551 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate prepolymer and 88 parts by mass of ON-D56 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a polyol are used. 15 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) as an agent, and fluororesin powder (Lublon L-5 having an average particle size of 0.2 μm) as a lubricating filler : Daikin Industries, Ltd.) 30 parts by mass, conductive copolyparaphenylene-3,4'-oxydiphenylene-terephthalamide fiber (conductive organic fiber (C)) cut to a length of 0.6 mm 20 mass The surface layer material (D) was adjusted by mixing the parts.

(Formation of a two-layer belt)
The above-mentioned base material B is coated on a cylindrical mold, the surface layer material (D) is applied to the outer surface, and heated at a temperature of 80 ° C. for 120 minutes to thermoset the surface layer. The urethane layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.43 mm. The thickness of each layer of the belt was a surface layer of 0.35 mm and a base material of 0.08 mm. The material constituting the surface layer of this belt had a volume resistivity of 1 × 10 ¹¹ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A70.

<Example 5>
The material of the base material is the same material as in Example 1, the base material A is coated on a cylindrical mold, conductive organic fibers (A) are used on the outer surface, and the distance between the fibers is 800 μm. A nonwoven fabric woven into a woven fabric was laminated (equivalent to 18 parts by mass per 100 parts by mass of resin). Next, the coating liquid of the same surface layer material (B) as in Example 2 was applied while impregnating the conductive organic fibers (A), and heated at a temperature of 80 ° C. for 120 minutes to produce a thermosetting urethane for the surface layer. The layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.33 mm. The thickness of each layer of this belt was 0.25 mm for the surface layer and 0.08 mm for the base material. The material constituting the surface layer had a volume resistivity of 5 × 10 ¹¹ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A30.

<Example 6>
The same material as in Example 1 was used as the material for the base material. The base material A was coated on a cylindrical mold, and conductive organic fibers (B) were coated on the outer surface of the base material A with an interfiber distance of 300 μm. Was wound in a spiral shape (corresponding to 22 parts by mass per 100 parts by mass of resin). Next, the coating liquid of the same surface layer material (B) as in Example 2 was applied while impregnating the conductive organic fibers (B), and heated at a temperature of 80 ° C. for 120 minutes to produce a thermosetting urethane for the surface layer. The layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.33 mm. The thickness of each layer of this belt was 0.25 mm for the surface layer and 0.08 mm for the base material. The material constituting the surface layer had a volume resistivity of 1 × 10 ¹² Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A30.

<Example 7>
The material of the base material is the same as that of Example 1, and the material of the surface layer is 100 parts by mass of TC-551 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the isocyanate prepolymer and ON-D56 (Japan) as the polyol. 88 parts by mass of Polyurethane Industry Co., Ltd., and 15 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): Degussa Japan Co., Ltd.) as a conductive agent, conductive copolyparaphenylene The surface layer material (E) was prepared by mixing 20 parts by mass of 3,4'-oxydiphenylene terephthalamide fiber (conductive organic fiber (C)) cut to a length of 0.6 mm. The above-mentioned base material A is coated on a cylindrical mold, the surface layer material (E) is applied on the outer surface, and heated at 80 ° C. for 120 minutes to thermoset the surface layer. The urethane layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.23 mm. The thickness of each layer of this belt was 0.18 mm for the surface layer and 0.08 mm for the base material. The material constituting the surface layer of this belt had a volume resistivity of 1 × 10 ¹¹ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A70.

<Comparative Example 1>
(Substrate & surface layer material)
The material of the base material is the same as that of Example 1, and the material of the surface layer is 100 parts by mass of coronate 4370 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the isocyanate prepolymer and Nipponran 4378 (Nippon Polyurethane Industry) as the polyol. 80 parts by mass) and carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) 22 parts by mass are mixed as a conductive agent. (F) was adjusted.

(Formation of a two-layer belt)
A cylindrical mold is coated with 0.08 mm of the above-mentioned base material A, and a coating liquid of the surface layer material (F) is applied to the outer surface thereof, heated at 80 ° C. for 120 minutes, and the surface layer The thermosetting urethane layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.48 mm. The thickness of each layer of this belt was a surface layer of 0.4 mm and a base material of 0.08 mm. The material constituting the surface layer of this belt had a volume resistivity of 5 × 10 ¹⁰ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A82.

<Comparative example 2>
(Substrate & surface layer material)
The material of the base material is the same as that of Example 1, and the material of the surface layer is 100 parts by mass of TC-551 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the isocyanate prepolymer and ON-D56 (Japan) as the polyol. 93 parts by mass of Polyurethane Industry Co., Ltd., and 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) as a conductive agent, polymetaphenylene isophthalamide fiber (Teijin Techno Products Co., Ltd. "Conex") 20 mass parts of what was cut into 0.6 mm in length was mixed, and surface layer material (G) was adjusted.

(Formation of a two-layer belt)
The above-mentioned base material A is coated on a cylindrical mold, the surface layer material (G) is applied to the outer surface, and heated at 80 ° C. for 120 minutes to thermoset the surface layer. The urethane layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.38 mm. The thickness of each layer of this belt was a surface layer of 0.30 mm and a base material of 0.08 mm. The material constituting the surface layer of this belt had a volume resistivity of 3 × 10 ¹¹ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A50.

<Comparative Example 3>
Only the base material of Example 1 was used as the semiconductive belt of Comparative Example 3.

<Comparative Example 4>
The same material as in Example 1 was used as the base material. The material of the surface layer is composed of 100 parts by mass of MC-B86 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate prepolymer and 277 parts by mass of ON-D55 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a polyol. 30 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) as an agent, and Chemitry LF-700 (manufactured by Soken Kagaku Co., Ltd.) as a component imparting lubricity The surface layer material (H) was adjusted by mixing 35 parts by mass.

(Formation of a two-layer belt)
The above-mentioned base material A is coated on a cylindrical mold, the surface layer material (H) is applied to the outer surface, and heated at a temperature of 80 ° C. for 100 minutes to thermoset the surface layer. The urethane layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.35 mm. The thickness of each layer of this belt was 0.27 mm for the surface layer and 0.08 mm for the base material. The material constituting the surface layer had a volume resistivity of 2 × 10 ¹⁰ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A28.

<Comparative Example 5>
The material of the base material is the same as that of Example 1, and the material of the surface layer is an isocyanate prepolymer, 100 parts by mass of TC-551 (manufactured by Nippon Polyurethane Industry Co., Ltd.) and a polyol, ON-D56 (Japan) 93 parts by mass of Polyurethane Industry Co., Ltd., and 25 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): Degussa Co., Ltd.) as a conductive agent, and inorganic fiber shape As a filler, 30 parts by mass of 8 potassium titanate fibers (manufactured by Otsuka Chemical Co., Ltd., Tesmo D) having a fiber diameter of 0.3 to 0.6 μm and a fiber length of 10 to 20 μm are mixed to form a surface layer material. (I) was adjusted.

(Formation of a two-layer belt)
The above-mentioned substrate A is coated on a cylindrical mold, and the coating solution of the surface layer material (I) is applied to the outer surface thereof and heated at 80 ° C. for 120 minutes to thermoset the surface layer. The urethane layer was cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.33 mm. The thickness of each layer of this belt was 0.25 mm for the surface layer and 0.08 mm for the base material. The material constituting the surface layer of this belt had a volume resistivity of 9 × 10 ¹⁰ Ωcm at an applied voltage of 100V. The durometer hardness of the surface layer was A50.

<Evaluation>
For the semiconductive belts obtained in Examples 1 to 7 and Comparative Examples 1 to 5, the transfer image quality (blur, holo character, color registration) and embossed paper runnability were evaluated. The results are shown in Table 1.

(Evaluation of transfer image quality)
The obtained semiconductive belt was modified from Fuji Xerox Co., Ltd. Docu Color 1255CP to evaluate the transfer image quality. As the toner, a spherical toner having a shape factor (SF) of 132 and a volume average particle diameter of 5.5 μm was used.

For the volume average particle diameter of the toner, a Coulter Counter TA-II type (manufactured by Beckman-Coulter) was used as a measuring device, and ISOTON-II (manufactured by Beckman-Coulter) was used as the electrolyte.
As a measurement method, 1.0 mg of a measurement sample was added to 2 ml of a 5% aqueous solution of sodium alkylbenzene sulfonate as a dispersant. This was added to 100 ml of the electrolytic solution to prepare an electrolytic solution in which the sample was suspended. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for 1 minute, and the particle size distribution of particles having a diameter of 2 to 60 μm is measured using the Coulter counter TA-II with an aperture diameter of 100 μm. The average particle size was determined. The measured number of particles is 50,000.

(Blur evaluation)
The occurrence of blur was evaluated according to the following criteria.
○: The occurrence of blur is slight and there is no problem in image quality. △: The occurrence of blur is present but there are few problems in image quality. ×: The occurrence of blur is present and there is a problem in image quality.

(Holo character evaluation)
The occurrence of holo-characters was evaluated according to the following criteria.
○: No image quality problem △: Slight occurrence, few image quality problems ×: Image quality problem

(Color cash register evaluation)
The occurrence of cash register deviation was evaluated according to the following criteria.
○: No image quality problem △: Slight occurrence, few image quality problems ×: Image quality problem

The image quality was evaluated when a halftone of 30% magenta was copied by running an embossed paper with a step of 50 μm, and evaluated according to the following criteria. As the toner, a spherical toner having a shape factor (SF) of 125 and a volume average particle diameter of 5.5 μm was used.
○: No problem in image quality in continuous 1000-sheet running test △: No problem in image quality in continuous 1000-sheet running test ×: Problem in image quality

From the results of Table 1, the semiconductive belts of Examples 1 to 7 of the present invention were free from image quality defects and could stably obtain excellent image quality over a long period of time.
On the other hand, in Comparative Example 1, since the hardness of the surface layer was slightly high, the embossed paper was not suitable, the occurrence of microslip was slight, and the color registration deteriorated.
In Comparative Example 2, although the hardness of the surface layer was low, the embossed paper was suitable. However, since insulating fibers were mixed, the resistance variation varied greatly and image quality defects (blur, holocharacter) occurred.
Since Comparative Example 3 is a resin having a hard surface, the color registration is good, but there is no embossed paper suitability.
In Comparative Example 4, since the surface layer was soft, the embossed paper was suitable, but the color registration deteriorated.
In Comparative Example 5, the hardness of the surface layer was low, so that it was suitable for embossed paper, but because the insulating fibers were mixed, the resistance variation was large and image quality defects (blur, holocharacter) occurred.

It is sectional drawing which shows the structure of the semiconductive belt of this invention. It is a figure which shows the measuring method of volume resistivity. 1 is a schematic diagram for explaining a main part of an image forming apparatus to which the present invention is applied. 1 is a schematic diagram for explaining a main part of a tandem type image forming apparatus to which the present invention is applied. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductive belt 2 Surface layer 3 Base material 21 Photosensitive drum (Image holding body)
22 Intermediate transfer belt (intermediate transfer member)
23 Bias roller (second transfer means)
24 Paper tray 25 Black developing device 26 Yellow developing device 27 Magenta developing device 28 Cyan developing device 29 Intermediate transfer body cleaner 33 Peeling claw 41 Belt roller 42 Backup roller 43 Belt roller 44 Belt roller 45 Conductive roller (first transfer means)
46 Electrode roller 51 Cleaning blade 61 Recording paper 62 Pickup roller 63 Feed roller 71 Toner cartridge 72 Fixing roll 73 Backup roll 74 Tension roll 75 Secondary transfer roll 76 Paper path 77 Paper tray 78 Laser generator 79 Photoconductor 80 Primary transfer roll 81 Drive Roll 82 Transfer Cleaner 83 Charging Roll 84 Photoconductor Cleaner 85 Developer 86 Intermediate Transfer Member

Claims (2)

A substrate;
A surface layer provided on the substrate, containing conductive organic fibers, and having a durometer hardness of A30 to A70;
A semiconductive belt characterized by comprising: An image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming a latent image on the surface of the image carrier, and a developing unit for developing the latent image with toner to form a toner image And a transfer unit that transfers the toner image to a recording medium, and a fixing unit that heat-fixes the toner image to the recording medium.
The transfer means has a semiconductive belt provided with a base material and a surface layer provided on the base material, containing conductive organic fibers, and having a durometer hardness of A30 to A70. Image forming apparatus.

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