JP2009115965A - Semiconductive seamless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductive seamless belt, preventing uneven transfer, turbulence of an image and separation failure to obtain a clear image when using the belt as a functional belt of an image forming apparatus such as an intermediate transfer belt, a transfer and fixing belt and a transfer and conveying belt. <P>SOLUTION: In the semiconductive seamless belt including an outer layer and an inner layer, both of which are mainly composed of polyimide resin, the blet contains conductive material, the volume resistivity of the outer layer is larger than that of the inner layer, and the volume resistivity of the whole belt is 1.0×10<SP>10</SP>to 1.0×10<SP>12</SP>Ωcm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductive seamless belt that can be used as an intermediate transfer belt, a transfer fixing belt, a transfer conveyance belt, and the like in an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, and a facsimile machine.

  Conventionally, as an electrophotographic recording apparatus for forming and recording an image by an electrophotographic system, a copying machine, a laser beam printer, a facsimile, and a complex machine of these are known. In this type of apparatus, the image on the image carrier such as a photosensitive drum is temporarily transferred to an intermediate transfer belt for the purpose of improving the life of the apparatus and making it applicable to various recording materials. An intermediate transfer method that performs batch transfer is partially employed, and a transfer fixing method in which a fixing operation is simultaneously performed at the time of the transfer is also being studied. In addition, for the purpose of speeding up the creation of a color image document, a system is also employed in which transfer is performed while a recording material is conveyed by a transfer conveyance belt.

  As a semiconductive belt that can be used for such intermediate transfer belts, transfer fixing belts, transfer conveyance belts, etc., a semiconductive material in which a conductive material such as carbon black is dispersed in a polyimide resin having excellent mechanical properties and heat resistance. A well-known belt is known (Patent Document 1, Patent Document 2).

  However, the semiconductive belts disclosed in these publications are unsatisfactory in practical use due to uneven transfer, poor separation, and image disturbance.

  In addition, a laminated seamless belt composed of a polyimide-based resin and another material such as silicone-based or fluorine-based rubber is also known (Patent Document 3, etc.).

  However, such a multilayer belt is insufficient in durability due to insufficient delamination due to insufficient interlayer adhesion. Further, the uniform dispersion of the conductive material on the silicone rubber or fluororubber is not sufficient, and the electric resistance value varies widely, which is not satisfactory in practical use.

  Under such circumstances, a semiconductive belt composed of a plurality of layers with different surface resistivity mainly composed of polyimide resin has been proposed (Patent Document 4).

  However, in the case of Patent Document 4, although the variation in the surface resistivity is somewhat improved, the image forming property is not satisfactory.

JP-A-63-311263 JP-A-5-77252 JP 59-77467 A JP 7-156287 A

  Accordingly, the present invention provides a semiconductive material that is free from uneven transfer and image distortion when used as a functional belt of an image forming apparatus such as an intermediate transfer belt, a transfer fixing belt, and a transfer conveyance belt, so that a clear image can be obtained. An object is to provide a seamless belt.

The semiconductive seamless belt of the present invention is a semiconductive seamless belt composed of an outer layer and an inner layer mainly composed of a polyimide resin, wherein the belt contains a conductive substance, and the volume resistivity of the outer layer is It is larger than the volume resistivity of the inner layer, and the volume resistivity of the whole belt is 1.0 × 10 ^{10 to} 1.0 × 10 ¹² Ω · cm.

  By adjusting the volume resistivity of the outer layer to be higher than the volume resistivity of the inner layer and adjusting the volume resistivity of the entire belt within the above range, the toner image can be transferred satisfactorily, preventing toner scattering, etc. A functional belt excellent in formability can be obtained. In addition, since a polyimide resin is used, a functional belt excellent in electrical characteristics, mechanical characteristics, and heat resistance can be obtained, which is effective.

  In the semiconductive seamless belt of the present invention, the ratio of the thickness of the inner layer to the thickness of the outer layer (inner layer / outer layer) is preferably 0.5 to 1.5. By adjusting to the said range, the semiconductive seamless belt excellent in image forming property can be obtained, and it is effective.

  In the semiconductive seamless belt of the present invention, the conductive material preferably contains at least carbon black. By using carbon black as the conductive material, the volume resistivity can be easily controlled, which is effective.

    As a method for producing a semiconductive seamless belt of the present invention, first, a dispersion for an outer layer and an inner layer in which a conductive substance is dispersed is prepared. Next, it is necessary to prepare a conductive material-dispersed polyamic acid solution by dissolving and polymerizing tetracarboxylic dianhydride or its derivative (tetracarboxylic acid component) and a diamine component in each prepared dispersion. Furthermore, an imide conversion reaction is performed using the polyamic acid solution to prepare an outer layer and an inner layer of the semiconductive seamless belt of the present invention.

  Here, as a method for preparing the outer layer and the inner layer of the semiconductive seamless belt, for example, (i) a belt-like product of the outer layer polyimide precursor was formed in the outer layer polyamic acid solution, and an imide conversion reaction was performed. Thereafter, a polyamic acid solution for the inner layer is applied on the outer layer film to form a belt-like product of the polyimide precursor for the inner layer, and an imide conversion reaction is performed, or (ii) a polyimide precursor for the outer layer using the polyamic acid solution for the outer layer After forming the body belt-like material, the reaction was temporarily stopped before the imide conversion reaction was completed, and the inner layer polyimide precursor solution was formed with the inner layer polyimide precursor belt-like material. The method of performing reaction is mentioned. The latter is preferable because a belt without delamination is easily formed.

    Below, the preparation method of the semiconductive seamless belt of this invention is demonstrated concretely.

<Preparation of conductive substance dispersion>
When preparing the semiconductive seamless belt of the present invention, first, a conductive material dispersion in which a conductive material is dispersed is prepared. Specific examples of the conductive substance include inorganic compounds such as carbon black, aluminum, nickel, tin oxide, and potassium titanate, and conductive polymers typified by polyaniline and polypyrrole. In particular, it is preferable to use carbon black from the viewpoint of resistance control and resistance reduction.

  Examples of the carbon black include channel black, furnace black, ketjen black, and acetylene black. These can be used alone or in combination of two or more. The type of these carbon blacks can be selected as appropriate depending on the intended conductivity. Depending on the application, those that prevent oxidative deterioration such as oxidation treatment and graft treatment, and those that have improved dispersibility in solvents Is preferable, and in particular, oxidized carbon black is preferably used.

  The oxidized carbon black can be obtained by oxidizing the carbon black to give an oxygen-containing functional group (for example, carboxyl group, quinone group, lactone group, hydroxyl group, etc.) to the surface.

  The oxidation treatment is performed by an air oxidation method in which the material is brought into contact with and reacts with air in a high temperature atmosphere, a method in which nitrogen oxide or ozone is reacted at room temperature, a method in which ozone is oxidized at low temperature after air oxidation at high temperature, be able to. In the oxidized carbon black obtained by the above method, an excessive current flows in part and is not easily affected by oxidation due to repeated voltage application. In addition, the effect of the oxygen-containing functional group adhering to the surface provides high dispersibility in polyimide, can reduce resistance variation, reduce electric field dependency, and make it difficult for electric field concentration due to transfer voltage to occur. . As a result, the electrical resistance is prevented from lowering due to the transfer voltage, the uniformity of the electrical resistance is improved, the change in resistance due to the electric field dependency and the environment is small, and the occurrence of image quality defects such as the paper running portion being whitened is suppressed Therefore, high image quality can be obtained.

  Carbon black having an average particle size based on primary particles of 1 μm or less, particularly 0.001 to 0.5 μm, is preferably used from the viewpoint of controlling variation in electrical characteristics due to uneven distribution.

Regarding the carbon black content, the volume resistivity of the outer layer in the semiconductive seamless belt of the present invention is larger than the volume resistivity of the inner layer, and the volume resistivity of the entire belt is 1.0 × 10 ¹⁰ to 1. It is determined appropriately depending on the type of carbon black to be added so as to be 0 × 10 ¹² Ω · cm. For example, the outer layer is adjusted to 20 to 21 parts by weight with respect to 100 parts by weight of the polyimide resin solid content, and the inner layer is adjusted to 22 to 23 parts by weight with respect to 100 parts by weight of the polyimide resin solid content. The volume resistivity of the outer layer can be prepared substantially higher than the volume resistivity of the inner layer.

  As a method for adding and dispersing carbon black, for example, it is preferable to prepare a dispersion liquid in which carbon black is added in advance to an organic polar solvent that can be used in the present invention.

  A known dispersion method can be applied to the carbon black dispersion method. For example, after adding carbon black to the solvent, a dispersion work can be performed by appropriately selecting a method such as nanomizer, ball mill, sand mill, basket mill, triple roll mill, planetary mixer, bead mill, homogenizer, and ultrasonic wave. . Among these, nanomizer, bead mill, and ultrasonic are particularly preferable. By using the above dispersion method, a dispersion with a narrow particle size distribution of carbon black and small variations can be obtained. In addition, the permeability and adsorption of the polyamic acid solution to the carbon surface are also good.

  Note that a dispersant can be further added to increase the affinity between the conductive material such as carbon black and the solvent.

  Although it will not specifically limit as a dispersing agent if the objective of this invention is met, For example, a polymeric dispersing agent is mentioned. Examples of the polymer dispersant include poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylazide), poly (N-vinylformamide), poly (N-vinylacetamide), poly (N— Vinylphthalamide), poly (N-vinylsuccinamide), poly (N-vinylurea), poly (N-vinylpiperidone), poly (N-vinylcaprolactam), poly (N-vinyloxazoline), etc. Alternatively, a plurality of polymer dispersants can be added.

  The amount of the dispersant added is preferably 0.01 to 10% by weight and more preferably 0.1 to 5% by weight with respect to the carbon black in order to uniformly disperse the carbon black. When the amount of the dispersant added is less than 0.01% by weight or more than 10% by weight, no effect on the dispersion can be obtained.

<Preparation of polyamic acid solution>
The raw material liquid for the polyimide resin can be obtained by preparing a polyamic acid solution by polymerizing a tetracarboxylic dianhydride or derivative thereof (tetracarboxylic acid component) and a diamine component in a solvent. The polyamic acid is obtained by reacting approximately equimolar amounts of a tetracarboxylic acid component and a diamine component in an organic solvent, and is usually used in the form of a solution.

  Examples of the tetracarboxylic acid component include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride Perylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylenetetracarboxylic dianhydride, and the like. Details, 3,3 ', 4,4'-biphenyl tetracarboxylic dianhydride. These can be used alone or in combination of two or more.

  Examples of the diamine component include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3 '-Diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl-4,4'-biphenyldiamine, benzidine, 3,3'-dimethylbenzidine, 3, 3′-dimethoxybenzidine, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane, 2,4-bis (β-amino-t-butyl) toluene, bis (P-β-amino-tert-butylphenyl) ether, bis (p -Β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-amino-pentyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4, 4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethi Diamine, 5-methylnonamethylenediamine, 2,11-diaminododecane, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 1,12-diamino Examples include octadecane and 2,2-bis [4- (4-aminophenoxy) phenyl] propane. These can be used alone or in combination of two or more.

  In addition, the reaction temperature of the tetracarboxylic acid component and the diamine component is preferably 80 ° C. or less, particularly preferably 5 to 50 ° C. The polymer component of the polyamic acid solution may be one obtained by copolymerizing, blending, or mixing these tetracarboxylic acid components and diamine components as long as the object of the present invention can be achieved.

  Although the viscosity of the polyamic acid solution obtained by the above reaction increases, if the heating is performed as it is, the viscosity of the polyamic acid solution decreases. Utilizing this phenomenon, the polyamic acid solution can be adjusted to a predetermined viscosity. The heating temperature at this time is preferably 50 to 90 ° C.

  Examples of the catalyst that contributes to the reaction between the tetracarboxylic acid component and the diamine component include imidazoles, secondary amines, and tertiary amines. For example, 2-methylimidazole, 4-methyl-2-phenylimidazole, 2-phenylimidazole, imidazole, isoquinoline and the like can be mentioned. Among these, 2-phenylimidazole is preferable in terms of improving mechanical strength. The addition amount of the catalyst is preferably 0.1 to 2 molar equivalents, more preferably 0.2 to 1 molar equivalents with respect to 1 molar equivalent of the polyamic acid in the polyamic acid solution.

  In addition, a surfactant, a dispersion stabilizer and the like can be used within the scope of the object of the present invention.

<Method for producing semiconductive seamless belt>
A method for producing the semiconductive seamless belt of the present invention using the polyamic acid solution obtained as described above will be described below. In addition, as a manufacturing method demonstrated here, the belt-like thing of the polyimide precursor for outer layers is formed with the polyamic acid solution for outer layers mentioned above, reaction is once stopped before imide conversion reaction is completed, and also the polyamide for inner layers The present invention relates to a method of performing an imide conversion reaction on both layers after forming a belt-like product of an inner layer polyimide precursor with an acid solution.

  First, the outer layer polyamic acid solution is supplied into a cylindrical mold, and is uniformly spread by centrifugal force on the inner peripheral surface of the mold by a rotary centrifugal molding method. At this time, the viscosity of the solution is preferably 1 to 1000 Pa · s (25 ° C.) with a B-type viscometer. In other cases, it is difficult to uniformly develop during centrifugal molding, which causes variations in the thickness of the polyimide belt.

  After the centrifugal molding, heating is performed and the solvent is evaporated to cure until the coating film can maintain the belt shape (belt-like material of the polyimide precursor for the outer layer). The heating temperature at this time is preferably 50 to 250 ° C. Immediately after heating, the fluidity of the polyamic acid increases, so the mold is rotated to suppress variations in the coating thickness. In addition, as a method of heating evenly, there is a method that improves circulation of hot air that is heated while rotating the mold, a method that decreases the heating rate while rotating the mold on the turntable, and a temperature lower than the drying temperature. And a method of lowering the rate of temperature rise to the drying temperature.

  Subsequently, the inner layer polyamic acid solution is applied to the inner surface of the outer layer polyimide precursor belt-like material, and the inner layer polyimide precursor is coated in the same manner as the outer layer polyimide precursor belt-like material manufacturing method. A belt is prepared.

  Next, the polyimide precursor belt-like material composed of the outer layer and the inner layer is heated to perform an imide conversion reaction. In order to promote the imide conversion reaction, heating is performed at a high temperature of 250 to 450 ° C. In this case, the heating method described above is also used. Then, it is possible to use a method in which the temperature is lowered to a temperature lower than the drying temperature and the rate of temperature rise to the drying temperature is lowered. By the above process, a semiconductive seamless belt can be obtained.

  In the semiconductive seamless belt obtained by the above-described method, the volume resistivity of the outer layer can be adjusted to be larger than the volume resistivity of the inner layer by appropriately selecting conductive materials and combining them in an appropriate amount. The volume resistivity of the outer layer is larger than the volume resistivity of the inner layer. For example, when the same polyimide resin is used for both the outer layer and the inner layer, it is prepared by adding more conductive material to the inner layer than to the outer layer. can do. When the volume resistivity of the outer layer is made larger than that of the inner layer, the amount of the conductive material contained in the outer layer can be reduced, thereby suppressing the friction of the outer layer and peeling after forming the semiconductive seamless belt. Thus, it is possible to obtain a semiconductive seamless belt having excellent workability and image forming properties.

In the present invention, the volume resistivity of the entire belt is 1.0 × 10 ^{10 to} 1.0 × 10 ¹² Ω · cm, and 5.0 × 10 ^{10 to} 5.0 × 10 ¹¹ Ω · cm. Preferably there is. When the volume resistivity is less than 1.0 × 10 ¹⁰ Ω · cm, the amount of transferred toner is reduced and only low density recording can be obtained. On the other hand, when the volume resistivity exceeds 1.0 × 10 ¹² Ω · cm, when the toner image is transferred, the intermediate transfer belt or the like is charged and is separated from the image carrier, so that peeling discharge easily occurs. Scatters and tends to produce a blurred image. In addition, since the belt itself is charged, a static elimination mechanism may be necessary.

  The thickness of the outer layer and the inner layer in the semiconductive seamless belt of the present invention is not particularly limited as long as the object of the present invention can be achieved, but in order to control the volume resistivity of the entire belt, The ratio of the thickness of the inner layer to the inner layer (inner layer / outer layer) is preferably 0.5 to 1.5, more preferably 0.7 to 1.3. When the ratio is less than 0.5, when the toner image is transferred, the intermediate transfer belt or the like is charged and separated from the image carrier, so that peeling discharge is likely to occur, and the transferred toner image is scattered and unclear. It is easy to become an image. On the other hand, when the ratio exceeds 1.5, energization of the inner layer tends to occur, the volume resistivity tends to decrease, the amount of transferred toner decreases, and only low density recording can be obtained.

Further, when the semiconductive seamless belt of the present invention is used as a functional belt such as an intermediate transfer belt, the surface resistivity is 1.0 × 10 ^{11 to} 1.0 × 10 ¹³ Ω / □. Preferably, it is 5.0 × 10 ^{11 to} 5.0 × 10 ¹² Ω / □. If the surface resistivity is less than 1.0 × 10 ¹¹ Ω / □, an excessive current flows between the intermediate transfer belt or the like and the image carrier, so that the toner image transferred to the belt returns to the image carrier. Therefore, it tends to be a transfer defect or a blurred image. On the other hand, when the surface resistivity exceeds 1.0 × 10 ¹³ Ω / □, when the toner image is transferred, the intermediate transfer belt or the like is charged and is separated from the image carrier, and thus the discharge discharge easily occurs. The image is scattered and tends to be a blurred image.

  Since the semiconductive seamless belt of the present invention uses a polyimide resin, it is used for an intermediate transfer belt, a transfer fixing belt or a transfer conveyance belt of an electrophotographic recording apparatus having excellent electrical characteristics, mechanical characteristics and heat resistance. Is.

  Examples and evaluation methods specifically showing the configuration and effects of the present invention will be described below.

[Evaluation test]
(1) Measurement of volume resistivity The surface resistivity at 25 ° C. and 60% RH was measured with a Hiresta UP MCP-probe (manufactured by Mitsubishi Chemical, URS probe) under an applied voltage of 100 V and a measurement value of 1 minute value. The measurement was carried out at 10 points per belt as described above, and the average value was obtained.

(2) Measurement of surface resistivity The surface resistivity at 25 ° C. and 60% RH was measured with a Hiresta UP MCP-probe (manufactured by Mitsubishi Chemical, URS probe) under an applied voltage of 500 V and a measurement value of 1 minute value. The measurement was carried out at 10 points per belt as described above, and the average value was obtained.

(3) Image evaluation
The obtained semiconductive seamless belt was incorporated into an actual copying machine as a tandem intermediate transfer belt, and an image formation test was performed. An image having good image and belt drivability was evaluated as ◯, and an image having an image defect that could be visually recognized was evaluated as ×.

Example 1
In a ball mill, 30.4 g of carbon black (Degussa, Special Black 4) dried in 761 g of N-methyl-2-pyrrolidone (NMP) (equivalent to 19% by weight with respect to the solid content of the polyimide resin) was obtained using a ball mill. For 6 hours at room temperature. In this carbon black-dispersed NMP solution, 129 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 47.2 g of p-phenylenediamine are dissolved and stirred for 4 hours at room temperature in a nitrogen atmosphere. By reacting, a carbon black-dispersed polyamic acid solution (liquid a) was obtained.

  In the same manner, 40.0 g of carbon black (Degussa, Special Black 4) dried in 800 g of NMP was mixed with a ball mill for 6 hours at room temperature. did. In this carbon black-dispersed NMP solution, 128.6 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 47.2 g of p-phenylenediamine are dissolved and stirred at room temperature for 4 hours in a nitrogen atmosphere. Then, a carbon black-dispersed polyamic acid solution (liquid b) was obtained.

  The liquid a was applied to the inner surface of a mold having an inner diameter of 300 mm and a length of 500 mm with a dispenser to a thickness of 200 μm, and then rotated at 1500 rpm for 10 minutes to obtain a uniform coating layer as an outer layer. While rotating the mold at 250 rpm, hot air of 60 ° C. was applied from the outside of the mold for 30 minutes, heated at 180 ° C. for 60 minutes, and then cooled to room temperature.

  Next, on the inner surface of the outer layer polyimide precursor belt-like material obtained in this state, the liquid b is similarly applied to a thickness of 200 μm and dried to form the inner layer polyimide precursor belt shape on the inner surface of the outer layer. Formed. Thereafter, the temperature was raised to 350 ° C. at a rate of 2 ° C./min, and further heated at 350 ° C. for 30 minutes to remove the solvent, remove dehydrated ring-closing water, and complete the imide conversion reaction. Then, it returned to room temperature, peeled from the metal mold | die, and obtained the target semiconductive seamless belt. This belt had a total thickness of 83 μm, an outer layer thickness of 43 μm, and an inner layer of 40 μm.

  The obtained belt was measured at 10 locations for volume resistivity (log (Ω · cm)) and surface resistivity (log (Ω / □)), and an average value thereof was determined. When this belt was actually mounted on a copying machine as an intermediate transfer belt and image formation was performed, a good image could be obtained.

(Comparative Example 1)
Semi-conductive by the same method as in Example 1 except that the liquid a was applied to the inner surface of the mold with a dispenser to a thickness of 300 μm and the liquid b was applied to a thickness of 100 μm. I got a seamless belt. This belt had a total thickness of 82 μm, an outer layer thickness of 62 μm, and an inner layer of 20 μm.

  When the obtained belt was actually mounted on a copying machine as an intermediate transfer belt and image formation was performed, defects were found in the image obtained immediately after the start of evaluation.

(Comparative Example 2)
Semi-conductive by the same method as in Example 1 except that the liquid a was applied to the inner surface of the mold with a dispenser to a thickness of 100 μm and the liquid b was applied to a thickness of 300 μm. I got a seamless belt. This belt had a total thickness of 82 μm, an outer layer thickness of 21 μm, and an inner layer of 61 μm.

  When the obtained belt was actually mounted on a copying machine as an intermediate transfer belt and image formation was performed, defects were found in the image obtained immediately after the start of evaluation.

From the above evaluation results, it was confirmed that the semiconductive seamless belt having a predetermined volume resistivity was excellent in image forming property in the examples. On the other hand, it was confirmed that the comparative example deviating from the predetermined volume resistivity was inferior in image forming property.

Claims (3)

Both are semiconductive seamless belts composed of an outer layer and an inner layer mainly composed of a polyimide resin,
The belt contains a conductive material;
The volume resistivity of the outer layer is greater than the volume resistivity of the inner layer,
The semiconductive seamless belt characterized in that the volume resistivity of the whole belt is 1.0 × 10 ^{10 to} 1.0 × 10 ¹² Ω · cm.   2. The semiconductive seamless belt according to claim 1, wherein the ratio of the thickness of the inner layer to the thickness of the outer layer (inner layer / outer layer) is 0.5 to 1.5.   The semiconductive seamless belt according to claim 1 or 2, wherein the conductive material contains at least carbon black.