JP2007171746A - Semiconductive belt and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve toner transfer efficiency to a sheet having large ruggedness. <P>SOLUTION: The semiconductive belt 1 has an elastic layer 2 formed on a base material 3. The elastic layer 2 is composed of two layers, i.e. an inner elastic layer 2b and an outer elastic layer 2a having durometer hardness higher than that of the inner elastic layer 2b, the thickness of the outer elastic layer 2a is 0.01 to 0.05 mm, and the thickness of the inner elastic layer 2b is in a range of three to ten times the thickness of the outer elastic layer 2a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductive belt used in an image forming apparatus using an electrophotographic system such as a copying machine or a printer, and an image forming apparatus using the semiconductive belt.

  In an image forming apparatus using an electrophotographic system, first, a uniform charge is formed on the surface of an image carrier made of a photoconductive photoreceptor 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).

  In the image forming apparatus employing the intermediate transfer body method, PC (polycarbonate), PVDF (polyvinylidene fluoride), polyalkylene phthalate, and PC / PAT (polyalkylene terephthalate) blend materials are used as the intermediate transfer body. , ETFE (ethylene tetrafluoroethylene copolymer) / PC, ETFE / PAT, PC / PAT blend materials, etc. have been proposed to use conductive endless belts of thermoplastic resins (for example, Patent Documents 2 to 7). reference.).

  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 8 and 9.)

  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.

  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 an elastic member has been proposed. However, 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, see Patent Documents 10 and 11).

  As a belt material having a multilayer structure, for example, a multilayered endless belt made of plastic or a belt in which a polyolefin urethane layer is applied to the surface of a rubber belt has been proposed (see, for example, Patent Documents 12 and 13). .

  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.

  Also, the belt with a polyolefin urethane layer, which is a thermoplastic elastomer, applied to the rubber belt surface is spray-coated with polyolefin urethane on the rubber belt, resulting in variations in the coating thickness 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, in the two-layer constitution belt using the 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 14).

  However, when the surface layer is made of an elastic member made of a thermosetting urethane resin, it has a JIS A hardness of 30 to 70 degrees, so that microslip occurs between the opposing image carriers, Problems such as deterioration of color registration (color registration: color misregistration) 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, so it is necessary to increase the thickness of the belt. The surface layer is greatly deformed at the portion, and the surface layer is deteriorated during long-term use, resulting in a problem that a good transfer image quality cannot be obtained.

JP-A-62-206567 JP-A-6-095521 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 JP-A-5-77252 Japanese Patent Laid-Open No. 10-63115 Japanese Patent Laid-Open No. 9-305038 Japanese Patent Laid-Open No. 10-240020 Japanese Patent Laid-Open No. 11-24428 Japanese Patent Laid-Open No. 11-45015 JP 2001-282009 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. In other words, the present invention has good toner transfer properties even on paper with large irregularities, such as embossed paper, which has conventionally been difficult to print with high image quality, and can form a nip shape at the transfer portion. An object of the present invention is to provide an image forming apparatus capable of stably obtaining a high-quality transfer image quality with excellent image quality defects such as hollow image (holo character) and toner scattering (blur) with excellent transfer image quality. And

  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 having an elastic layer on a substrate, the elastic layer comprising two layers of an inner elastic layer and an outer elastic layer having a durometer hardness higher than that of the inner elastic layer, The outer elastic layer has a thickness in the range of 0.01 to 0.05 mm, and the inner elastic layer has a thickness of 3 to 10 times the thickness of the outer elastic layer. .

  <2> The semiconductive belt according to <1>, wherein a difference in durometer hardness between the outer elastic layer and the inner elastic layer is 20 degrees or more.

  <3> The semiconductive belt according to <1> or <2>, wherein a durometer hardness of the outer elastic layer is in a range of A70 / S to A90 / S.

  <4> The semiconductive belt according to any one of <1> to <3>, wherein a durometer hardness of the inner elastic layer is in a range of A30 / S to A70 / S.

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

  <6> The semiconductive belt according to any one of <1> to <5>, wherein the base material has a Young's modulus in a range of 1000 to 8000 MPa.

  <7> The semiconductive belt according to <6>, wherein the base material contains a polyimide resin.

  <8> A latent image carrier, charging means for charging the surface of the latent image carrier, latent image forming means for forming a latent image on the charged latent image carrier surface, and developing means for developing the latent image And a transfer unit that transfers the developed developed image onto the recording medium, and a fixing unit that fixes the developed image on the recording medium, and at least one of the transfer unit and the fixing unit includes <1 > To <7> An image forming apparatus using the semiconductive belt according to any one of <7>.

<9> The image forming apparatus according to <8>, wherein a spherical toner having a shape factor SF defined by the following formula (1) of 140 to 100 is used.
Formula (1)
SF = [(maximum length of toner particles) ² ] / [(projected area of toner particles) × π × 1/4 × 100]

  In the present invention, the elastic layer of the surface layer is composed of two layers, the outer side is a high-hardness elastic layer, and the inner side is a low-hardness elastic layer. Image defects such as hollow out of line image (holo character), toner scattering (blur), color shift, etc. are remarkably small, and the surface has high hardness, so there is little generation of micro slip, and a conventional elastic layer was used. In this case, the deterioration of color registration can be suppressed. In addition, the present invention can provide an image forming apparatus that includes the semiconductive belt and can stably obtain high-quality transfer image quality.

  Embodiments of the present invention will be described below.

<Semiconductive belt>
The semiconductive belt of the present invention will be described with reference to FIG. A semiconductive belt 1 of the present invention shown in FIG. 1 (a) is used in an electrophotographic image forming apparatus, and as shown in FIGS. 1 (a) and 1 (c), a semiconductive belt comprising at least three layers. In the conductive belt 1, the surface layer is composed of an elastic layer 2 having a two-layer structure, and the outer elastic layer 2a is provided with a lubricating component that exhibits lubricity, and has a thickness of 0.01 mm to 0.05 mm, durometer hardness Is an A70 / S to A90 / S thermosetting urethane resin composition, and the inner elastic layer 2b has a durometer hardness of A30 / S to A70 / S and a thickness of 0.05 mm to 0.5 mm. A semiconductive belt characterized by being a thermosetting urethane resin composition.

  Here, FIG. 1A is a perspective view of an example of the semiconductive belt of the present invention, FIG. 1B is a cross-sectional view taken along the line II of FIG. 1A, and FIG. c) is a sectional view taken along the line II-II in FIG.

  As described above, the semiconductive belt according to the present invention has a two-layer elastic layer as a surface layer, a high-hardness elastic layer provided with a lubricating component on the outside, and a low-hardness elastic layer on the inside. By providing the above, the occurrence of microslip in the surface layer can be suppressed, and by providing a low-hardness elastic layer on the inside, the transferability of uneven paper such as embossed paper can be improved. By adopting a three-layer structure made of materials, it is possible to satisfy the balance between flexibility and rigidity, which cannot be obtained with a single material structure.

(Configuration of elastic layer material)
In the present invention, it is an elastic layer composed of at least two layers, and the outer elastic layer 2a shown in FIGS. 1B and 1C has a hardness of 70 / S to 90 / S and a thickness of The inner elastic layer 2b is a thermosetting urethane resin composition having a durometer hardness of A30 / S to A70 / S and a thickness of 0.05 mm to 0.5 mm. As a result, the transferability of an uneven paper such as embossed paper can be improved. Since the outer elastic layer is provided with a lubricating component, it is difficult for toner filming to occur on the belt, and since the hardness is 70 / S to 90 / S, the microslip between the image carrier and the cleaning member can be obtained. Can be suppressed.

  In addition, by using a thermosetting elastomer composition, a surface layer with little deformation over time and excellent durability can be formed.

-Resin for elastic layer-
In the present invention, examples of the thermosetting urethane resin component used for the outer elastic layer 2a and the inner elastic layer 2b of the surface layer shown in FIGS. 1B and 1C include a polyether-based polyurethane resin. The polyether polyurethane resin is obtained by curing a polyether polyol with a polyisocyanate compound. In this case, the polyether polyol can be obtained by the reaction of an initiator having an active hydrogen atom with an alkylene oxide. Examples of the initiator include potassium hydroxide, propylene glycol, ethylene glycol, glycerin, hexane, triol, triol. Examples include ethanolamine, diglycerin, pentaerythritol, ethylenediamine, methylglucotite, and aromatic diamine. Examples of alkylene oxides include propylene oxide (PO) and ethylene oxide (EO).

  The polyisocyanate compound has two or more isocyanate groups in the molecule, and specifically, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, tolidine diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, phenylene diisocyanate. , Xylylene diisocyanate, tetramethyl xylylene diisocyanate, cyclohexane diisocyanate, lysine ester diisocyanate, lysine ester triisocyanate, undecane triisocyanate, hexamethylene triisocyanate, triphenylmethane triisocyanate, and polymers, derivatives and modified products of these isocyanate compounds Examples thereof include hydrogenated products. Among these, aliphatic and alicyclic isocyanates such as hexamethylene diisocyanate and isophorone diisocyanate are preferably used because they are excellent in ozone resistance and heat resistance. Depending on the purpose, isocyanates may be mixed and used.

(Ingredients that develop lubricity)
The component that exhibits lubricity is not particularly limited, and examples thereof include a monomeric fluorinated compound obtained by grafting fluorine to the terminal, and a lubricious filler such as resin powder.

-Lubricity imparting monomer-
The component that exhibits lubricity is not particularly limited, and examples thereof include an acrylic monomer (Soken Kagaku chemistry LF-700) formed by grafting fluorine at the terminal.

-Addition amount of lubricity-imparting monomer-
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 (PVF) resin, polyvinylidene fluoride (PVDF) resin, tetrafluoroethylene (TFE) resin, chlorotrifluoroethylene (CTFE) resin, and ETFE (ethylene-tetrafluoroethylene copolymer). ), CTFE-ethylene copolymer, PFA (TFE-perfluoroalkyl vinyl ether copolymer), FEP (TFE-hexafluoropropylene (HFP) copolymer), EPE (TFE-HFP-perfluoroalkyl vinyl ether copolymer) One or more resin powders of fluorinated compounds such as) are used.

-Amount of lubricant filler material added-
The fluororesin is preferably a fine powder having an average particle size of 1 μm or less. When the average particle diameter is larger than 1 μm, the surface of the intermediate transfer belt becomes rough, and transferability is deteriorated. Moreover, the addition amount of a lubricous filler is 5-80 mass parts with respect to 100 weight part of resin materials, Preferably, it is 10-60 mass parts. When the amount of the lubricating filler added 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, the thermosetting elastomer forming the surface layer is hard. Therefore, there is a case where followability cannot be obtained with special paper having uneven surfaces such as colored paper or embossing.

(Surface roughness of surface layer)
Further, the surface roughness Rz of the surface layer 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 that comes into contact, and if it exceeds 9.0 μm, toner as an image material may adhere to cause image quality deterioration such as halftone unevenness. There is. The surface roughness was measured in accordance with JIS B0601 (2001) under the conditions of a measurement length of 0.8 mm, a cut-off of 0.8 mm, and a measurement speed of 0.6 mm / Sec, and the average value of the measured values at three locations.

(Hardness of outer elastic layer)
As for the hardness of the elastic material outside the surface layer of the present invention, the durometer hardness according to JIS K6253 (1997) is A70 / S to A90 / S, preferably A75 / S to A85 / S. When the durometer hardness of the material outside the elastic layer is A70 / S to A90 / S, the occurrence of microslip can be suppressed in contact with the opposing image carrier, cleaning member, and the like.

(Inner elastic layer hardness)
As for the hardness of the outer elastic layer of the surface layer of the present invention, the durometer hardness according to JIS K6253 (1997) is A30 / S to A70 / S, preferably A40 / S to A60 / S. Since the durometer hardness of the surface layer material is A70 / S to A90 / S, the followability to special paper with unevenness such as embossed paper is improved, so that the toner transferability can be improved.

  In addition, the durometer hardness of the surface layer material was obtained by laminating a sheet-shaped surface layer material and measuring the standard hardness according to JIS K6253 (1997) as a thickness of 6 mm.

  If the difference in hardness between the outer elastic layer and the inner elastic layer is 20 degrees or more, the effects of the outer elastic layer and the inner elastic layer can be exhibited without impairing the effects.

(Elastic layer thickness)
The thickness of the outer elastic layer 2a is preferably 0.01 mm to 0.05 mm, and more preferably 0.02 to 0.04 mm. The film thickness ratio (the thickness of the inner elastic layer with respect to the thickness of the outer elastic layer) is preferably 3 to 10 times.

  When the thickness of the outer elastic layer 2a is less than 0.01 mm, it may not be possible to suppress the occurrence of microslip in contact with the opposing image carrier, cleaning member, etc. The followability to special paper with irregularities such as embossed paper may deteriorate. Also, when the film thickness ratio is less than 3 times, the elastic layer 2 itself is thin, and the followability to special paper with unevenness such as embossed paper is deteriorated. As a result, the color registration is also deteriorated. To do. On the other hand, when the film thickness ratio exceeds 10 times, generation of micro slip cannot be suppressed.

<Base material>
The material of the belt base material 3 shown in FIG. 1 preferably uses a resin composition having a Young's modulus of 1000 MPa or more, preferably 2000 MPa or more, and satisfies the mechanical properties. 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 the 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.

  As a polyimide resin, for example, an aromatic tetracarboxylic acid component and an aromatic diamine component are obtained by reacting 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′-diaminophenylsulfone, 4,4′-diamino Zobenzen, 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. 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 the conductive polymer 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, can be mentioned polyacetylene, polypyrrole, polyphenylene vinylene and the like, can be used these conductive polymers undoped state, or in a doped state. By using the above-mentioned conductive agent, conductive polymer, or surfactant in combination of one or more, the above-described electrical resistance can be stably obtained.

  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. Oxidation-treated carbon black having a pH of 5 or less is preferable because 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 give a carboxyl group, a quinone group, a lactone group, a hydroxyl group, and the like. 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 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. 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. For this reason, in the present invention, carbon black obtained by the Nes method manufacturing and adjusted to have a pH of 5 or less by post-processing is also considered to be 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 of pH 5.0 or less has good dispersion stability because it has good dispersibility in the resin since it has oxygen-containing functional groups such as carboxyl group, hydroxyl group, quinone group, and lactone group on the surface of carbon black. Thus, the variation in resistance of the semiconductive belt can be reduced, the electric field dependency is also reduced, and the electric field concentration due to the transfer voltage is less likely to occur. Further, in the oxidized carbon black, an excessive current flows in part and is less susceptible to oxidation due to repeated voltage application, so that the stability of electrical resistance over time can be improved.

  The pH of the oxidized carbon black can be 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 oxidized carbon black preferably has a volatile component content of 1 to 25% by mass, more preferably 3 to 20%, and even more preferably 3.5 to 15% by mass. . When the content of the volatile component is less than 1% by mass, the effect of the oxygen-containing functional group adhering to the outside is lost, and the dispersibility in the binder resin may be reduced. On the other hand, if the content of the volatile component is higher than 25%, it may be decomposed when dispersed in the resin composition, or the amount of water adsorbed on the outer oxygen-containing functional group is increased. The appearance of the surface layer or the substrate may be deteriorated.

  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 1-25 mass%. 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, these carbon blacks are preferably substantially different in conductivity from each other, for example, those having different physical properties such as degree of oxidation treatment, DBP oil absorption, specific surface area by BET method utilizing nitrogen adsorption, etc. Use. 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.

  Specific examples of the oxidation-treated carbon black include “Printex 150T” (pH 4.5, volatile content 10.0% by mass) and “Special Black 350” (pH 3.5, volatile content 2.2) manufactured by Degussa. %), “Special Black 100” (pH 3.3, volatile matter 2.2% by mass), “Special Black 250” (pH 3.1, volatile matter 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 content 14.0) %), “Special Black 550” (pH 2.8, volatile content 2.5% by mass), “Special Black 6” (pH 2.5, volatile content 18.0% by mass), “Color Black FW2”. 0 ”(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 content 16) .5 mass%), “MONARCH 1000” manufactured by Cabot (pH 2.5, volatile content 9.5 mass%), “MONARCH 1300” manufactured by Cabot (pH 2.5, volatile content 9.5 mass%), manufactured by Cabot “ “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 3.5) Mass%) and the like.

  Oxidized carbon black has good 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. Is preferably increased. 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. .

  When the content of the oxidized carbon black is 10 to 30% by mass, 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% by mass, the uniformity of the 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% by mass, it may be difficult to obtain a desired resistance value. Further, it is more preferable to contain 18 to 30% by mass of oxidized carbon black. By containing 18 to 30% by mass of oxidized carbon black, the effect can be maximized and the surface resistivity can be improved. The internal unevenness and the electric field dependency can be remarkably improved.

(Volume resistivity)
In the semiconductive belt of the present invention, the volume resistivity of the surface layer and the substrate is preferably 1 × 10 ⁸ to 1 × 10 ¹³ Ωcm, more preferably the surface layer and the substrate. Is 1 × 10 ⁹ to 1 × 10 ¹² Ωcm. 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.

In addition, the volume resistivity of the substrate is preferably 1 × 10 ⁸ to 1 × 10 ¹³ Ωcm, and preferably 1 × 10 ⁹ to 1 × 10 ¹² Ωcm. If the volume resistivity of the substrate is 1 × 10 ⁸ to 1 × 10 ¹³ Ωcm, the toner is scattered around the image due to the electrostatic repulsion between the toners and the force of the fringe electric field near the image edge. (Blurring) problems are less likely to occur.

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.). The method will be described with reference to the drawings, which consist of a schematic plan view of Fig. 2 (a) showing an example of a circular electrode and a schematic cross-sectional view of Fig. 2 (b). A voltage application electrode A ′ and a second voltage application electrode B ′ are provided, the first voltage application electrode A ′ having a cylindrical electrode part C ′ and an inner diameter larger than the outer diameter of the cylindrical electrode part C ′. And a cylindrical ring-shaped electrode portion D ′ surrounding the column-shaped electrode portion C ′ at regular intervals, and the columnar electrode portion C ′ and the ring-shaped electrode portion D ′ of the first voltage application electrode A ′. The semiconductive belt 1 is sandwiched between the second voltage application electrode B ′ and the first voltage 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 ′ in the pressure application electrode A ′ is measured, The volume resistivity ρv (Ωcm) of the conductive belt 1 can be calculated, where t represents the thickness of the semiconductive belt 1 in the following formula.
Formula: ρv = 19.6 × (V / I) × t

  In the semiconductive belt of the present invention, the Young's modulus of the base material is preferably 1000 MPa or more, more preferably 1500 MPa or more, and further preferably 2000 MPa or more. When a resin material 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 stabilized. Obtainable. However, as the thickness of the belt increases, the amount of deformation of the outer surface of the belt at the belt bending portion such as the drive 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. In addition, although the larger Young's modulus of a base material is so good, it is preferable that it is 8000 MPa or less practically, and it is more preferable that it is 6000 MPa or less practically. The Young's modulus of the substrate can be controlled within the above range by selecting the chemical structure of the resin material to be used, and the Young's modulus can be increased as the material includes an aromatic ring structure.

  The Young's modulus is obtained by performing a tensile test according to JIS K 7127 (1999), drawing a tangent line to the curve in the initial strain region of the obtained stress / strain curve, and determining the slope.

  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. If it 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.

  Further, the thickness of the surface layer (two elastic layers) 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 affecting 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. In addition, when the Young's modulus of the resin composition of the substrate is a high Young's modulus of 1000 MPa to 8000 MPa, the mechanical properties as a semiconductive belt can be satisfied.

  The semiconductive belt of the present invention having the above-described configuration is excellent in that there is no decrease in resistance due to transfer voltage, no problem of shape deformation with time, no dependence on electric field, and little change in electrical resistance due to the environment. Have the same properties. 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 semiconductive belt of the present invention has a surface layer (two elastic layers) mainly composed of the thermosetting urethane resin as described above and a substrate made of a resin material having a Young's modulus of 1000 MPa to 8000 MPa. Further, the surface layer and the base material may contain additives other than the described conductive agent. Further, in addition to the surface layer and the base material, it can be further multilayered within a range not impairing the effects of the present invention.

  Since the formation of the semiconductive belt is endless, it 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 a material of each layer into a sheet shape by an extrusion molding method, and then laminating the material on a metal core and heat-treating it to form a two-layer belt. Then, the base material can be formed into a belt shape, laminated on the metal core, and the surface layer can be formed thereon. Further, a three-layer belt can be formed by simultaneous molding while laminating the surface layer and the base material.

<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 carried on an image carrier such as a photosensitive drum is subjected to primary transfer sequentially to an intermediate transfer member Any of a forming apparatus, a tandem 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 carried 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 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.

  As an example, FIG. 3 shows a schematic diagram of a color image forming apparatus using the semiconductive belt of the present invention as an intermediate transfer belt and sequentially repeating primary transfer. 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 carrier, an intermediate transfer belt 22 as an intermediate transfer member, a bias roller 23 (second transfer means) as a transfer electrode, and a sheet for supplying recording paper as a transfer medium. Tray 24, developing unit 25 using Bk (black) toner, developing unit 26 using Y (yellow) toner, developing unit 27 using M (magenta) toner, developing unit 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 image transferred to the intermediate transfer belt 22 reaches the secondary transfer portion where the bias roller 23 (second transfer means) is installed by the rotation of the intermediate transfer belt 2. The secondary transfer unit includes a bias roller 23 installed on the surface side on which the toner image of the intermediate transfer belt 22 is carried, 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 carried 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 subjected to removal of residual toner by an intermediate transfer body cleaner 29 provided on the downstream side of the secondary transfer portion to prepare for the next transfer. 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 aspect 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 for four colors (black, yellow, magenta, cyan). Further, the present invention can be applied to a tandem color image forming apparatus in which the photoconductor 79 for each color is disposed on an intermediate transfer body (intermediate transfer belt) 86. FIG. 4 is a schematic diagram for explaining a main part of a tandem type 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, in FIG. 4, a charging roll 83 (charging device) that uniformly charges the surface of the photoreceptor 79, a laser generator 78 (exposure device) that exposes the surface of the photoreceptor 79 to form an electrostatic latent image, and the photoreceptor 79 A latent image formed on the surface is developed using a developer to form a toner image, a developing device 85 (developing device), and a photoconductor cleaner 84 (cleaning device) that removes toner and dust adhering to the photoconductor. The fixing roller 72 for fixing the toner image on the transfer material can be optionally provided by a known method as necessary.

  Even in the tandem image forming apparatus having the above-described 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 incorporated and used as an intermediate transfer belt or a transfer conveyance belt in an image forming apparatus, it is preferable to use a spherical toner as the toner. By using a spherical toner as the toner, the material constituting the transfer surface has a low hardness and is difficult to deform along the surface, so there is no high quality image (holo character, blur, color registration). Transfer image quality can be obtained.

However, the spherical toner means that the shape factor / SF is 140-100. The shape factor is preferably 130 to 100 or less, and more preferably 120 to 100 or less. 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 spherical toner can preferably use 2 to 12 μm particles, more preferably 3 to 9 μm particles.

  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.

  Colorants 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, lamp black. Rose Bengal, C.I. I. Pigment raid 48: 1, C.I. I. Pigment raid 122, C.I. I. Pigment raid 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 fine 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 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, the particles obtained by the kneading and pulverization method in which the binder resin and the colorant are mixed, pulverized, and classified, if necessary, the release agent and the charge control agent 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 to obtain binder resin, colorant, release agent, charge control agent as required 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 if necessary, a release agent and a charge control agent are suspended in an aqueous solvent and granulated. Examples thereof include a dissolution suspension method. In addition, a manufacturing method may be performed in which the spherical toner obtained by the above method is used as a core, and agglomerated particles are further adhered 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% by mass) was dried with 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 in the minimum area collide after two split 1.4 mm ^2, by passing five times a path divided into two again, mixed, Table To obtain a carbon black-containing polyamic acid solution for the layer (A).

The polyamic acid solution containing carbon black (A) 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, after applying hot air of 60 ° C. for 30 minutes from the outside of the mold, it was heated at 150 ° C. for 60 minutes, returned to room temperature, peeled off from the mold, coated on the metal core, and 2 ° C. up to 360 ° C. The temperature was raised at a rate of temperature rise / minute, and further heated at 360 ° 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 peeled from the mold 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.

(Preparation of outer elastic layer (A1)):
The material of the surface layer is 100 parts by mass of Coronate 4362 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the isocyanate prepolymer and 5.4 parts by mass of Nippon Poly 4038 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the polyol. With respect to 100 parts by mass of the component, as a conductive agent, 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan), and as a component for imparting lubricity, Chemitry LF- 700 parts by mass (manufactured by Soken Kagaku Co., Ltd.) was mixed to prepare the surface layer material (A1).

  The durometer hardness of the outer elastic layer (A1) was A78 / S.

(Preparation of inner elastic layer (B1)):
As the material for the inner elastic layer, 100 parts by mass of TC-551 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the isocyanate prepolymer and 93 parts by mass of ON-D56 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the polyol are used. , 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan Co., Ltd.) as a conductive agent with respect to 100 parts by mass of the resin component, for the inner elastic layer The material (B1) was adjusted.

  The durometer hardness of the inner elastic layer material (B1) was A45 / S.

(Formation of a three-layer belt)
A cylindrical mold is coated with a 0.08 mm thick base material, the inner elastic layer (B1) coating solution is applied, and the inner elastic layer is thermally cured by heating at 120 ° C. for 2 hours. The functional urethane layer was cured. Next, a coating solution for the outer elastic layer (A1) is applied and heated at a temperature of 80 ° C. for 3 hours to cure the thermosetting urethane layer of the outer elastic layer to have an inner diameter of 168 mm, a width of 350 mm, and a thickness. A 0.33 mm three-layer belt is obtained. The thickness of each belt layer was 0.05 mm for the outer elastic layer, 0.2 mm for the inner elastic layer, and 0.08 mm for the base material. The material constituting the surface layer of this belt had a volume resistivity of 7 × 10 ¹¹ Ωcm at an applied voltage of 100V.

<Example 2>
(Formation of base material)
The same material as in Example 1 was used as the base material, and it was formed in the same manner as in Example 1.
(Preparation of outer elastic layer (A2)):
As an isocyanate prepolymer, 100 parts by mass of Coronate 4370 (manufactured by Nippon Polyurethane Industry Co., Ltd.) and 80 parts by mass of Nippon Run 4378 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a polyol are used. As a conductive agent, carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) 40 parts by mass, and as a component imparting lubricity, Chemitry LF-700 (manufactured by Soken Kagaku Co., Ltd.) ) 80 parts by mass were mixed to prepare the surface layer material (A2). The durometer hardness of the surface layer material (A2) was A82 / S.

(Preparation of inner elastic layer (B2)):
As the material of the inner elastic layer, 100 parts by mass of MC-C24 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate prepolymer and 63 parts by mass of ON-D57 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a polyol are used. , 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan Co., Ltd.) as a conductive agent with respect to 100 parts by mass of the resin component, for the inner elastic layer The material (B2) was adjusted.

  The durometer hardness of the inner elastic layer material (B2) was A58 / S.

(Formation of a three-layer belt)
A cylindrical mold is coated with a base material of 0.08 mm, the inner elastic layer (B2) coating solution is applied, heated at 100 ° C. for 3 hours, and the inner elastic layer thermosetting urethane The layer was cured. Next, a coating solution for the outer elastic layer (A2) is applied and heated at a temperature of 70 ° C. for 2 hours to cure the thermosetting urethane layer of the outer elastic layer to have an inner diameter of 168 mm, a width of 350 mm, and a thickness. A 0.28 mm three-layer belt is obtained. The thickness of each belt layer was 0.03 mm for the outer elastic layer, 0.17 mm for the inner elastic layer, and 0.08 mm for the base material. The material constituting the surface layer of this belt had a volume resistivity of 7 × 10 ¹¹ Ωcm at an applied voltage of 100V.

<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% by mass), dry 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 solid content, Add to 26 parts by mass, and use a collision type disperser (GeanusPY manufactured by Seanas), collide after splitting into two parts with a pressure of 200 MPa and a minimum area of 1.4 mm ² , and pass again through the path that splits into two parts five times. And mixed to obtain a polyamic acid solution (B) containing carbon black for a substrate.

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, after applying hot air of 60 ° C. for 30 minutes from the outside of the mold, it was heated at 150 ° C. for 60 minutes, returned to room temperature, peeled off from the mold, coated on the metal core, and 2 ° C. up to 360 ° C. The temperature was raised at a rate of temperature rise / minute, and further heated at 400 ° 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 peeled from the mold 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.

(Preparation of outer elastic layer (A3)):
The material of the surface layer is 100 parts by mass of coronate 4370 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate prepolymer and 80 parts by mass of Nippon Run 4378 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a polyol. As a conductive agent, 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) as a conductive agent, and fluorine having an average particle diameter of 0.2 μm as a lubricating filler. Resin powder (Lublon L-5: manufactured by Daikin Industries, Ltd.) 30 parts by mass was mixed to prepare a surface layer material (A3). The durometer hardness of the surface layer material (A3) was A85 / S.

(Preparation of inner elastic layer (B3)):
As the material for the inner elastic layer, 100 parts by mass of TC-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 are used. , 25 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan Co., Ltd.) as a conductive agent with respect to 100 parts by mass of the resin component, for the inner elastic layer The material (B3) was adjusted. The durometer hardness of the inner elastic layer material (B3) was A33 / S.

(Formation of a three-layer belt)
A cylindrical mold is coated with a 0.08 mm base material, and the inner elastic layer material (B3) coating solution is applied, heated at 80 ° C. for 2 hours, and the thermosetting of the surface layer. The urethane layer was cured. Next, a coating liquid for the outer elastic layer (A3) is applied and heated at a temperature of 70 ° C. for 3 hours to obtain a three-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.30 mm. The thickness of each layer of this belt was 0.02 mm for the outer elastic layer, 0.2 mm for the inner elastic 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.

<Example 4>
(Formation of base material)
The same material as in Example 1 was used as the base material, and it was formed in the same manner as in Example 1.

(Preparation of outer elastic layer (A4))
The material of the surface layer is 100 parts by mass of coronate 4387 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the isocyanate prepolymer and 6.3 parts by mass of Nippon Poly 4038 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the polyol. As a conductive agent, 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan Co., Ltd.) as an electrically conductive agent, and an average particle diameter of 0.2 μm as a lubricating filler are used. 40 parts by mass of fluororesin powder (Lublon L-5: manufactured by Daikin Industries, Ltd.) was mixed to prepare a surface layer material (A4). The durometer hardness of the surface layer material (A4) was A70 / S.

(Preparation of inner elastic layer (B1))
As the material for the inner elastic layer, the inner elastic layer (B1) of Example 1 was used. The durometer hardness of the inner elastic layer material (B1) was A45 / S.

(Formation of a three-layer belt)
A cylindrical mold is coated with a 0.08 mm base material, the inner elastic layer (B1) coating solution is applied, heated at 120 ° C. for 2 hours, and the inner elastic layer thermosetting urethane The layer was cured. Next, a coating liquid for the outer elastic layer (A4) is applied and heated at a temperature of 120 ° C. for 2 hours to cure the thermosetting urethane layer of the outer elastic layer to have an inner diameter of 168 mm, a width of 350 mm, and a thickness. A 0.33 mm three-layer belt is obtained. The thickness of each belt layer was 0.05 mm for the outer elastic layer, 0.2 mm for the inner elastic layer, and 0.08 mm for the base material. The material constituting the surface layer of this belt had a volume resistivity of 7 × 10 ¹¹ Ωcm at an applied voltage of 100V.

<Example 5>
(Formation of base material)
The same material as in Example 1 was used as the base material, and it was formed in the same manner as in Example 1.

(Formation of a three-layer belt)
A cylindrical mold is coated with a 0.08 mm base material, the inner elastic layer (B1) coating solution is applied, heated at 120 ° C. for 2 hours, and the inner elastic layer thermosetting urethane The layer was cured. Next, a coating solution for the outer elastic layer (A1) is applied, heated at 120 ° C. for 2 hours, and the thermosetting urethane layer of the outer elastic layer is cured to have an inner diameter of 168 mm, a width of 350 mm, and a thickness. A 0.28 mm three-layer belt is obtained. The thickness of each layer of the belt was 0.05 mm for the outer elastic layer, 0.15 mm for the inner elastic layer, and 0.08 mm for the base material. The material constituting the surface layer of this belt had a volume resistivity of 7 × 10 ¹¹ Ωcm at an applied voltage of 100V.

<Example 6>
(Formation of base material)
The same material as in Example 1 was used as the base material.

(Preparation of outer elastic layer (A5))
The material of the surface layer is 100 parts by mass of coronate 4387 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the isocyanate prepolymer and 6.3 parts by mass of Nippon Poly 4038 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as the polyol. With respect to 100 parts by mass of the component, as a conductive agent, carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) 20 parts by mass and as a lubricating filler, an average particle size of 0.2 μm The surface layer material (A5) was prepared by mixing 40 parts by mass of fluororesin powder (Lublon L-5: manufactured by Daikin Industries, Ltd.). The durometer hardness of the surface layer material (A5) was A73 / S.

(Preparation of inner elastic layer (B2))
As the material of the inner elastic layer, the inner elastic layer (B2) of Example 2 was used. The durometer hardness of the inner elastic layer material (B2) was A58 / S.

(Formation of a three-layer belt)
A cylindrical mold is coated with a 0.08 mm base material, the inner elastic layer (B2) coating solution is applied, and heated at a temperature of 120 ° C. for 2 hours to heat the inner elastic layer thermosetting urethane. The layer was cured. Next, a coating liquid for the outer elastic layer (A5) is applied, heated at 120 ° C. for 2 hours, and the thermosetting urethane layer of the outer elastic layer is cured to have an inner diameter of 168 mm, a width of 350 mm, and a thickness. A 0.30 mm three-layer belt is obtained. The thickness of each layer of this belt was 0.05 mm for the outer elastic layer, 0.17 mm for the inner elastic 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 ¹¹ Ωcm at an applied voltage of 100V.

<Comparative Example 1>
(Substrate & surface layer material)
The material of the base material is the same as that of Example 1, the surface layer material is isocyanate prepolymer, 100 parts by weight of coronate 4370 (manufactured by Nippon Polyurethane Industry Co., Ltd.) and the polyol is Nipponran 4379 (Nippon Polyurethane Industry). 80 parts by mass), and 100 parts by mass of resin component, 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan) as a conductive agent The surface layer material (E) was prepared by mixing 20 parts by mass of a fluororesin powder having an average particle size of 0.2 μm (Lublon L-5: manufactured by Daikin Industries, Ltd.) as a lubricating filler. The durometer hardness of the surface layer material (E) was A91 / S.

(Formation of a two-layer belt)
A 0.08 mm base material is coated on a cylindrical mold, and a surface layer material (E) coating solution is applied, heated at 70 ° C. for 3 hours, and a thermosetting urethane layer as a surface layer. Is cured to obtain a two-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.28 mm. The thickness of each layer of this belt was 0.2 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 5 × 10 ¹⁰ Ωcm at an applied voltage of 100V.

<Comparative example 2>
(Substrate & surface layer material)
The material of the base material is the same material as in Example 1,
The material of the surface layer is 100 parts by mass of TC-551 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate prepolymer and 93 parts by mass of ON-D56 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a polyol. As a conductive agent, 20 parts by mass of carbon black (trade name: Printex 140U (pH 4.5%): manufactured by Degussa Japan Co., Ltd.) as an electrically conductive agent, and an average particle diameter of 0.2 μm as a lubricating filler are used. 20 parts by mass of fluororesin powder (Lublon L-5: manufactured by Daikin Industries, Ltd.) was mixed to prepare a surface layer material (F). The durometer hardness of the surface layer material (E) was A48 / S.

(Formation of a two-layer belt)
A cylindrical mold is coated with a 0.08 mm base material, and the surface layer material (F) coating solution is applied, heated at a temperature of 80 ° C. for 120 minutes, and a thermosetting urethane layer as a surface layer. Is 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 1 × 10 ¹¹ Ωcm at an applied voltage of 100V.

<Comparative Example 3>
(Formation of base material)
The same material as in Example 1 was used as the base material, and it was formed in the same manner as in Example 1.

(Preparation of outer elastic layer (A5))
As the material of the outer elastic layer, the outer elastic layer (A5) of Example 6 was used. The durometer hardness of the outer elastic layer material (A5) was A73 / S.

(Preparation of inner elastic layer (B1))
As the material for the inner elastic layer, the inner elastic layer (B1) of Example 1 was used. The durometer hardness of the inner elastic layer material (B1) was A45 / S.

(Formation of a three-layer belt)
A cylindrical mold is coated with a 0.08 mm base material, the inner elastic layer (B1) coating solution is applied, heated at 120 ° C. for 2 hours, and the inner elastic layer thermosetting urethane The layer was cured. Next, a coating liquid for the outer elastic layer (A5) is applied, heated at 120 ° C. for 2 hours, and the thermosetting urethane layer of the outer elastic layer is cured to have an inner diameter of 168 mm, a width of 350 mm, and a thickness. A 0.23 mm three-layer belt is obtained. The thickness of each belt layer was 0.05 mm for the outer elastic layer, 0.1 mm for the inner elastic 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 ¹¹ Ωcm at an applied voltage of 100V.

<Comparative example 4>
Using the same base material, outer elastic layer material, and inner elastic layer material as in Comparative Example 1, a three-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.68 mm is obtained. The thickness of each layer of the belt was 0.05 mm for the outer elastic layer, 0.55 mm for the inner elastic 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 ¹¹ Ωcm at an applied voltage of 100V.

<Comparative Example 5>
Using the same base material, outer elastic layer material, and inner elastic layer material as in Comparative Example 1, a three-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.385 mm is obtained. The thickness of each layer of the belt was 0.005 mm for the outer elastic layer, 0.3 mm for the inner elastic 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 ¹¹ Ωcm at an applied voltage of 100V.

<Comparative Example 6>
Using the same base material, outer elastic layer material, and inner elastic layer material as in Comparative Example 1, a three-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.44 mm is obtained. The thickness of each layer of the belt was 0.06 mm for the outer elastic layer, 0.3 mm for the inner elastic 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 ¹¹ Ωcm at an applied voltage of 100V.

<Comparative Example 7>
Using the same base material, outer elastic layer material, and inner elastic layer material as in Comparative Example 1, a three-layer belt having an inner diameter of 168 mm, a width of 350 mm, and a thickness of 0.84 mm is obtained. The thickness of each layer of the belt was 0.06 mm for the outer elastic layer, 0.7 mm for the inner elastic 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 ¹¹ Ωcm at an applied voltage of 100V.

<Evaluation>
With respect to the semiconductive belts obtained in Examples 1 to 6 and Comparative Examples 1 to 7, the transfer image quality (hollow character, color registration) and embossed paper runnability were evaluated. These results are shown in Table 1.

(Evaluation of transfer image quality)
Using a modified machine of Fuji Xerox Co., Ltd., Docu Color 1255CP shown in FIG. 3, the transfer image quality was evaluated while replacing the obtained semiconductive belt. The remodeled point is the point where the speed is 120 mm / s. As the paper, a product name “Rezac 66 (151 g / m ² )” manufactured by Fuji Xerox Office Supply Co., Ltd. was used. The paper size was A4. The output was performed for 5 cycles up to 1000 sheets with 200 sheets as one cycle.

(Holo character evaluation)
The occurrence of holo-characters was evaluated according to the following criteria.
◎: Image is good ○: Occurrence is slight but there is no problem in image quality △: Occurrence is slight and there are few problems in image quality ×: There is a problem in image quality

(Color cash register evaluation)
The occurrence of cash register misregistration was evaluated according to the following criteria.
◎: Image is good without misregistration ○: Occurrence is slight, but there is no problem in image quality △: Occurrence is slight, there are few problems in image quality ×: There is a problem in image quality

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.
○: 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 5 of the present invention were free from image quality defects and could stably obtain excellent image quality over a long period of time. Moreover, although the semiconductive belt of Example 6 was somewhat inferior to Examples 1 to 5 in running performance of embossed paper, there was not much problem in terms of image quality. On the other hand, in Comparative Example 1, the hardness of the surface layer material is slightly high, so there is no suitability for embossed paper, there is a defect in transfer image quality (holocharacter), there is a slight occurrence of micro slip, and the color registration is deteriorated. did. In Comparative Example 2, although the hardness of the surface layer was low, the embossed paper was suitable, but the color registration deteriorated due to the occurrence of micro slip. In Comparative Examples 3 to 7, the thickness of the outer elastic layer and the thickness of the inner elastic layer are not in the proper range, so that transfer image quality defects (holocharacters) are generated, color registration is deteriorated, and embossed paper is not suitable. Such a problem occurred.

  As an application example of the present invention, there is an application to an image forming apparatus such as a copying machine or a printer using an electrophotographic system, for example, an application to a fixing device for fixing a toner image on a paper with large unevenness for embossed paper.

It is the perspective view and sectional drawing which show the structure of the semiconductive belt of this invention. It is a figure explaining 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 image forming apparatus to which the present invention is applied. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Semiconductive belt, 2 Elastic layer, 2a Outer elastic layer, 2b Inner elastic layer, 3 Base material, 21 Photosensitive drum (image carrier), 22 Intermediate transfer belt (intermediate transfer body), 23 Bias roller ( (Second transfer means), 24 paper tray, 25 black developer, 26 yellow developer, 27 magenta developer, 28 cyan developer, 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, for 76 Route, 77 paper tray 78 laser generator, 79 photoconductor, 80 the primary transfer roll 81 drive roll 82 transfer cleaner, 83 charging roller, 84 photoconductor cleaner, 85 a developing unit, 86 an intermediate transfer member.

Claims (2)

A semiconductive belt having an elastic layer on a substrate,
The elastic layer is composed of two layers, an inner elastic layer and an outer elastic layer having a durometer hardness higher than that of the inner elastic layer.
The outer elastic layer has a thickness in the range of 0.01 to 0.05 mm;
And the thickness of the said inner side elastic layer is a semiconductive belt which is the range of 3-10 times with respect to the thickness of an outer side elastic layer. A latent image carrier, charging means for charging the surface of the latent image carrier, latent image forming means for forming a latent image on the surface of the charged latent image carrier, developing means for developing the latent image, and development In an image forming apparatus including a transfer unit that transfers the developed visible image onto a recording medium, and a fixing unit that fixes the visible image on the recording medium.
An image forming apparatus using the semiconductive belt according to claim 1 for at least one of the transfer unit and the fixing unit.

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