JP2008225181A - Semiconductive polyimide belt - Google Patents

Abstract

In the presence of a catalyst and in the absence of a dehydrating agent, by adjusting the molar ratio of the diamine component to a predetermined range, the balance between flexibility and rigidity is improved, and the shape of the belt surface can be improved even in continuous use. Disclosed is a semiconductive polyimide belt that hardly deteriorates and is excellent in durability and in which image deterioration is unlikely to occur.
A semiconductive polyimide belt containing a conductive filler, the belt being 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, p-phenylenediamine (component A) and 4 , 4′-diaminodiphenyl ether (component B) is polymerized in the presence of a catalyst and in the absence of a dehydrating agent, and the molar ratio of component A to component B is (A / B) = 7 A semiconductive polyimide belt that is / 3 to 3/7.
[Selection figure] None

Description

  The present invention relates to a semiconductive polyimide belt, and is useful as, for example, an intermediate transfer belt or a transfer conveyance belt mounted on an electrophotographic recording apparatus or the like.

  In devices such as copying machines, laser printers, video printers, facsimiles and their combined machines that form and record images using electrophotographic methods, recording toner etc. on an image carrier such as a photosensitive drum for the purpose of improving the life of the device. A method has been studied in which an image formed on an image carrier is temporarily transferred to an intermediate transfer belt and fixed on a recording sheet by avoiding a method of directly fixing an image formed via an agent on the recording sheet. .

  Here, if the intermediate transfer belt is deformed by a load such as tension due to continuous driving, the transfer image is deformed. Therefore, these belts are preferably made of a material having high strength and high elasticity. Conductive belts have been commonly used.

  In addition, with the widespread use of color image copying, in order to obtain a high-quality color image, resistance to such deformation has been further required. For example, the surface roughness can be set as the volume average particle diameter of the toner. In relation to this, a technique has been proposed in which the amount is limited to a predetermined range, the reverse transfer phenomenon is reduced, and uneven transfer is suppressed (for example, Patent Document 1).

  In addition, it has been proposed that the hardness of the belt surface of a semiconductive belt made of polyimide is regulated within a predetermined range, and the surface roughness of the belt surface is suppressed within a predetermined range (Patent Document 2). Here, the polyimide contains a copolymer obtained by polymerizing a tetracarboxylic acid component and a diamine component in the presence of a catalyst and a dehydrating agent.

  With respect to an apparatus for forming an image by an electrophotographic method, the formed image is required to have a higher resolution and a clearer image. In order to achieve these, in a series of transfer and cleaning processes, superior characteristics are required in many respects as compared with conventional techniques.

  Examples of specific effects on characteristics include (1) surface wear due to friction with members that contact the outer peripheral surface of the belt, such as photoreceptors, recording paper, and cleaning blades.

  In addition, when (2) a hard foreign component has fallen on the belt, or in a so-called two-component development method (a method using magnetic powder called a carrier when supplying toner to the photosensitive member), this is removed from the toner cartridge. When the carrier falls on the belt, the magnetic powder and foreign matter cause pressure between the transfer rolls in the primary and secondary transfer portions, or they are caught between the blade and the belt in the cleaning blade portion. The effect of the surface shape deterioration phenomenon such as destruction on the surface of the belt on the formed image can be mentioned, and the semiconducting belt made of a conventional polyimido film or the semiconducting content described in Patent Document 1 is no longer available. It can be said that it is practically difficult to deal with such effects with a sex belt.

  In addition, the semiconductive belt in Patent Document 2 uses a dehydrating agent, so that the dehydration reaction proceeds rapidly, the reaction cannot be controlled, and the polyamic acid gels. Become.

JP 2001-235946 A Japanese Patent Laid-Open No. 2004-287012

  Therefore, in view of the above circumstances, the present invention improves the balance between flexibility and rigidity, and is excellent in durability and less in the shape of the belt surface even in continuous use. An object is to provide a polyimide belt.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the following semiconductive polyimide belt and a method for producing the same, and have completed the present invention. .

  The present invention relates to a semiconductive polyimide belt containing a conductive filler, the belt being 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, p-phenylenediamine (component A) and 4 , 4′-diaminodiphenyl ether (component B) is polymerized in the presence of a catalyst and in the absence of a dehydrating agent, and the molar ratio of component A to component B is (A / B) = 7 This relates to a semiconductive polyimide belt that is 3/3 to 3/7.

  In the belt, in the presence of a catalyst and in the absence of a dehydrating agent, the molar ratio of the diamine component is set within a predetermined range, thereby improving the balance between flexibility and rigidity and deteriorating the shape of the belt surface even during continuous use. This is a semiconductive polyimide belt in which the phenomenon hardly occurs, the durability is excellent, and the image is hardly deteriorated.

The present invention provides a method for producing a semiconductive polyimide belt in which a tetracarboxylic acid component and a diamine component are dissolved and polymerized to obtain a copolymer in a dispersion in which a conductive filler is dispersed in a solvent.
In preparing the copolymer, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as the tetracarboxylic acid component, p-phenylenediamine (component A) and 4,4′-diamino as the diamine component Diphenyl ether (component B) is polymerized in a molar ratio of component A and component B (A / B) = 7/3 to 3/7 in the presence of a catalyst and in the absence of a dehydrating agent. The present invention relates to a method for manufacturing a conductive polyimide belt.

  By using the above manufacturing method, a semiconductive polyimide belt that improves the balance between flexibility and rigidity, is less likely to cause deterioration in the shape of the belt surface even during continuous use, has excellent durability, and is unlikely to cause image degradation. Obtainable.

  The surface dynamic friction coefficient using a steel ball of φ10 mm on the outer peripheral surface of the belt is 0.2 to 0.5, and the surface roughness Rz of the belt outer peripheral surface according to JIS B0601 (1994) is 0.2 to 1.0 μm. To a semiconductive polyimide belt. The belt is a semiconductive polyimide belt that is excellent in durability and hardly causes a reduction in image.

The present invention relates to a semiconductive polyimide belt containing carbon black as the conductive filler and having a surface resistivity in the range of 1.0 × 10 ^{9 to} 1.0 × 10 ¹³ Ω / □. The belt is a semiconductive polyimide belt in which dust generation of toner is suppressed and image deterioration hardly occurs.

  The present invention relates to a semiconductive polyimide belt containing a conductive filler, the belt being 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, p-phenylenediamine (component A) and 4 , 4′-diaminodiphenyl ether (component B) is polymerized in the presence of a catalyst and in the absence of a dehydrating agent, and the molar ratio of component A to component B is (A / B) = 7 This is a semiconductive polyimide belt that is 3/3 to 3/7.

  Examples of the conductive filler used in the present invention include carbon black such as ketjen black and acetylene black, metals such as aluminum and nickel, metal oxide compounds such as tin oxide, and conductive or semiconductive such as potassium titanate. One kind or two or more kinds of suitable materials such as powders or conductive polymers such as polyaniline and polyacetylene can be used, and the kind is not particularly limited.

  In addition, it is preferable that the addition amount of a conductive filler is small from a viewpoint of maintaining mechanical strength, such as the intensity | strength of a semiconductive polyimide belt, and bending resistance. Therefore, the use of carbon black that can exhibit conductive properties with a small addition amount is a more preferable embodiment.

  As carbon black, channel black or furnace black is preferable. About furnace black, since the dispersibility to a solvent improves by performing an oxidation process, what was oxidized appropriately is preferable. Furthermore, the oxidized furnace black imparts oxygen-containing functional groups (carboxyl group, ketone group, lactone group, hydroxyl group, etc.) to the surface by the treatment, so that it has good affinity with polar solvents and is electrically The surface of carbon black is less susceptible to oxidative degradation due to mechanical load. When such carbon black is used for a semiconductive belt, formation of a conductive path is difficult to occur, and resistance reduction can be prevented.

  The channel black used in the present invention includes Degussa Color Black FW200, Color Black FW2, Color Black 2V, Color Black FW1, Color Black FW18, Special Black 6, Color Black S170, Color Black S160, Special Black 5, Special Black Black 4, Special Black 4A, Printex 150T, Printex U, Printex V, Printex 140U, Printex 140V, etc., and oxidation black furnace black include Degussa Special Black 550, Special Black 350, Special Black 250, Special Black 100, Mitsubishi Chemical Corporation MA100, MA100R, MA100S, MA11, MA230, MA220 MA7, MA8, MA77, manufactured by Cabot Corporation MONARCH1000, MONARCH1400, MONARCH1300, MOGUL-L, REGAL400R, and the like.

  The content of carbon black is 5 to 30% by weight, preferably 5 to 25% by weight, more preferably 8 to 15% by weight, based on the polyimide resin solid content in the polyimide resin composition. If the amount is less than 5% by weight, the uniformity of electrical resistance tends to decrease, and if it exceeds 30% by weight, the high mechanical strength derived from the polyimide resin composition tends to decrease or the surface shape tends to deteriorate. is there. Further, if it is less than 5% by weight or more than 30% by weight, it is difficult to obtain a desired surface resistivity.

  As a dispersion method when carbon black is used as the conductive filler, a known dispersion method can be applied. For example, after adding carbon black to the solvent, it is effective to use a ball mill, sand mill, basket mill, three roll mill, planetary mixer, bead mill, ultrasonic dispersion, etc. Work can be done. By the above method, carbon black can be uniformly dispersed, and a semiconductive polyimide belt with little variation in electric resistance value can be obtained.

  In the method for producing a carbon black dispersion according to the present invention, carbon black is first added and dispersed in an organic polar solvent to prepare a carbon black dispersion. A surfactant may be used for improving dispersibility.

  The organic polar solvent used for the preparation of the dispersion is not particularly limited as long as it increases the dispersibility of carbon black, but N-methyl-2-pyrrolidone which can be used both as a dispersion for carbon black and as a solvent for polymerization reaction (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA) and the like are used.

  The method for producing a semiconductive polyimide belt of the present invention is a method of obtaining a copolymer by dissolving and polymerizing a tetracarboxylic acid component and a diamine component in a dispersion in which a conductive filler is dispersed in a solvent. In preparing the copolymer, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was used as the tetracarboxylic acid component, p-phenylenediamine (component A) and 4,4′-diamino were used as the diamine component. Diphenyl ether (component B) is polymerized at a molar ratio of component A to component B of (A / B) = 7/3 to 3/7 in the presence of a catalyst and in the absence of a dehydrating agent.

  In the present invention, the molar ratio of the component A to the component B is (A / B) = 7/3 to 3/7, and preferably (A / B) = 6/4 to 4/6. Due to the molar ratio within the above range, it is possible to obtain a semiconductive polyimide belt that is excellent in rigidity and flexibility, and that is unlikely to cause a surface shape deterioration phenomenon in continuous use, and that is excellent in durability and the like. When the molar ratio exceeds 7/3, the rigidity is strong and the flexibility is inferior. When the molar ratio is less than 3/7, the flexibility is high, and the belt breakage and creep characteristics are deteriorated.

  The reason for the above effect is not clear. Due to the molar ratio within the predetermined range, the belt surface wears in a series of transfer and cleaning processes, and carriers and hard foreign matters fall on the belt surface, and the primary and secondary transfer portions are pressurized between the transfer rolls. This is thought to be due to the fact that surface degradation due to continuous use, such as surface destruction due to contact or surface destruction due to foreign matter being caught between the blade and belt in the cleaning blade, is less likely to occur. .

  As the tetracarboxylic acid component used in the present invention, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride can be mainly used, but as long as the effects of the present invention are not impaired, The following can be used.

  For example, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic 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-di Carboxyphenyl) ether dianhydride, ethylenetetracarboxylic dianhydride and the like.

  In the present invention, p-phenylenediamine (PDA) and 4,4′-diaminodiphenyl ether (DDE) can be mainly used as the diamine component to be reacted with the tetracarboxylic acid component. As long as it is within the range that does not impair, one or more of the following may be appropriately selected and used.

For example, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3'-dichlorobenzidine, 4,4'-diaminodiphenyl sulfide-3,3'-diaminodiphenylsulfone, 1,5-diaminonaphthalene , M-phenylenediamine, 3,3′-dimethyl-4,4′-biphenyldiamine, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminophenylsulfone 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane, 2,4-bis (β-amino-tert-butyl) toluene, bis (p-β-amino-tert-butylphenyl)- Ter, bis (p-β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-amino-pentyl) benzene Zen, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylene Diamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxy Ethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methylnona Methylenediamine, 2,11-dia Minododecane, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 1,12-diaminooctadecane, 2,2-bis [4- (4 - aminophenoxy) phenyl] propane, _{piperazine, H 2 N (CH 2)} 3 O (CH 2) 2 OCH 2 NH 2, H 2 N (CH 2) 3 S (CH 2) 3 NH 2, H 2 N ( CH ₂ ) ₃ N (CH ₃ ) (CH ₂ ) ₃ NH _{2 and the} like.

  The organic polar solvent used when the tetracarboxylic acid component and the diamine component are reacted has a dipole whose functional group does not react with tetracarboxylic dianhydride or diamine. And what is inactive with respect to a system and acts as a solvent with respect to the polyamic acid which is a product is preferable. Moreover, those that act as a solvent for at least one of the reaction components, preferably both, are preferred.

  As such an organic polar solvent, N, N-dialkylamides are particularly useful. For example, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA), which have low molecular weight, are used. Etc. They can be easily removed from the polyamic acid and the polyamic acid molded article by evaporation, displacement or diffusion. Moreover, as organic polar solvents other than the above, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, Examples include pyridine, tetramethylene sulfone, dimethyltetramethylene sulfone and the like. These may be used alone or in combination.

  Furthermore, phenols such as cresol, phenol and xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like can be mixed singly or in combination with the organic polar solvent. However, in order to prevent lowering the molecular weight due to hydrolysis of the produced polyamic acid, it is preferable to avoid mixing water.

  The catalyst used in the present invention is preferably a tertiary amine, and examples include triethylamine, triethylenediamine, pyridine, picoline, quinoline, isoquinoline, and ruthiazine, and quinoline and isoquinoline are particularly preferable.

  The addition amount of the catalyst is preferably 0.05 to 2 molar equivalents, more preferably 0.1 to 1 molar equivalents relative to 1 molar equivalent of the polyamic acid in the polyamic acid solution. If it is less than 0.05 molar equivalent, the function as a catalyst cannot be obtained, and even if added in excess of 2 molar equivalents, almost no effect is obtained, and excess catalyst is evaporated during heat treatment during the production process. As a result, even after the polyimide belt is mounted on an electrophotographic recording apparatus or the like, the remaining catalyst gradually evaporates, and various physical properties such as the surface resistivity of the semiconductive polyimide belt change. There is a risk of causing problems such as changes in belt dimensions.

  In the present invention, a semiconductive polyimide belt is obtained in the absence of a dehydrating agent. This is because when a dehydrating agent is used, the dehydration reaction proceeds rapidly, the reaction cannot be controlled, and the polyamic acid gels, making it impossible to produce a stable semiconductive belt.

  The monomer concentration in the polyamic acid solution (the concentration of the tetracarboxylic acid component and the diamine component in the solvent) is set according to various conditions, but is preferably 5 to 30% by weight. Moreover, it is preferable to set reaction temperature to 80 degrees C or less, Most preferably, it is 5-50 degreeC. The reaction time is preferably 0.5 to 3 hours. The polymer component of the polyamic acid solution may be a copolymer or a blend of the above tetracarboxylic acid component and diamine component as long as the object of the present invention can be achieved.

  Using the polyamic acid solution thus obtained, the semiconductive polyimide belt of the present invention is produced by the following method.

  The carbon black-dispersed 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 film formation, heating is performed at 80 to 180 ° C. to remove the solvent.

  Next, the ring-closing imidization reaction is advanced by heating at a high temperature of 300 to 400 ° C., and then taken out from the mold. It is necessary to perform the solvent removal and the heating during the imidization reaction evenly. If it is not uniform, agglomeration variation of the carbon black occurs during the evaporation of the solvent, and the resistance value of the polyimide belt varies. As a method of heating evenly, there are a method of heating while rotating a mold, a method of improving the circulation of hot air, a method of charging at a low temperature, and a method of reducing the rate of temperature rise.

  The surface roughness Rz of the outer peripheral surface of the belt is preferably 0.2 to 1.0 μm, and more preferably 0.2 to 0.8 μm. If the surface roughness of the belt outer peripheral surface is defined in this way, the surface should be moderately rough even when it comes into contact with a member such as a photoconductor, recording paper, or cleaning blade in a series of transfer and cleaning processes. The contact area becomes smaller and the wear phenomenon is less likely to occur.

  In addition, even when foreign matter is caught in the cleaning blade, the stress on the blade rubber and the caught foreign matter varies greatly with the rotation of the belt due to the moderately rough outer peripheral surface of the belt, and it tends to fall off. The effect is easily obtained.

  Here, if the surface roughness Rz of the belt outer peripheral surface is less than 0.2 μm, it is difficult to obtain the above-described effects. On the other hand, the glossiness of the belt surface is high, but in this case, even if the scratches on the belt surface formed with continuous use have little effect on the image quality, the difference in surface glossiness is likely to occur. As a result, the measurement of the glossiness of the belt surface, which is performed when the density of the formed image is kept constant, is affected, and the printed image cannot be kept constant.

  On the other hand, if the surface roughness Rz of the belt outer peripheral surface exceeds 1.0 μm, the effect equivalent to that obtained in a predetermined range can be obtained in terms of improvement in durability, but the surface roughness is too large. In particular, toner residue is likely to occur particularly in the concave portion of the belt, and as a result, the formed image is affected.

  Here, examples of the method of processing the belt surface to a desired surface roughness include a method of polishing the belt after film formation using an abrasive such as sandpaper, a method of roughening by sandblasting, etc. In view of stabilizing the characteristics, a method of forming the inner surface of the cylindrical mold on which the raw material solution is applied to an appropriate roughness and transferring the shape to the outer peripheral surface of the belt is preferable.

  In addition, as to how to roughen the belt surface, the specified surface hardness can also be obtained by processing the belt surface into a concave shape by polishing using a polishing material such as sandpaper or by sandblasting. If the thickness and the surface roughness are satisfied, the problem can be solved. However, in particular, one of the reasons for defining the surface roughness is prevention of toner remaining at the flawed portion. In order to further increase the reliability in this regard, it is preferable to form a convex shape on the belt surface.

  In addition, in consideration of rubbing due to the transfer roll and blade rubber, if a convex shape is formed, these contact members are likely to make point contact at the convex shape portion, and wear at this portion is likely to proceed. Therefore, as a result, the surface shape difference such as the glossiness of the belt surface hardly occurs, which is more preferable. Regarding the scratch formation method (how to roughen the belt surface), as described above, it is preferable to form convex streaks on the outer surface of the belt by forming concave streaks on the inner surface of the cylindrical mold. . Further, regarding the method of roughening the belt surface, when streak-like irregularities are formed on the belt surface, streaks formed by continuous use are easily formed in the circumferential direction of the belt. Therefore, in order to make these inconspicuous, it is preferable to previously form streak-like irregularities in the circumferential direction of the belt.

  The semiconductive polyimide of the present invention preferably has a surface dynamic friction coefficient of 0.2 to 0.5, and more preferably 0.25 to 0.45. If the surface dynamic friction coefficient is less than 0.2, slip may occur. On the other hand, if it exceeds 0.5, there is a risk of driving failure in which the torque of the cleaning blade or the like increases.

When the semiconductive polyimide of the present invention is used as an intermediate transfer belt or the like of an electrophotographic recording apparatus, the surface resistivity is preferably 1.0 × 10 ^{9 to} 1.0 × 10 ¹³ Ω / □, More preferably, it is 1.0 × 10 ^{10 to} 1.0 × 10 ¹² Ω / □. If the surface resistivity is less than 1.0 × 10 ⁹ Ω / □, toner dust (scattering) may occur and the image quality may become coarse. On the other hand, if it exceeds 1.0 × 10 ¹³ Ω / □, the charge during transfer may remain on the belt and cause image unevenness. Note that the range of the surface resistivity is not limited as long as the effect of the present invention is not impaired.

  In addition, the present invention is not limited to an intermediate transfer belt, a transfer conveyance belt, and the like, and is also used for a belt and a film such as a fixing belt used when fixing a recording agent such as toner by heating in an electrophotographic recording apparatus. can do.

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

<Example 1>
<Method for producing carbon black dispersion>
In 2542 g of N-methyl-2-pyrrolidone (NMP), 184 g of dried carbon black (Degussa Special Black 4, 23 parts by weight based on 100 parts by weight of polyimide solids) was added. Next, this solution was mixed in a ball mill at room temperature for 6 hours to obtain a 7.2% by weight carbon black dispersion.

<Method for producing carbon black-dispersed polyamide solution>
50.2 g isoquinoline (0.2 molar equivalent) as a catalyst was added to 2726 g of the dispersion, and then 1820 g of NMP was added.

  Further, 572 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) as the acid dianhydride component and 105.1 g of p-phenylenediamine (PDA) (component A) as the diamine component And 194.6 g of 4,4′-diaminodiphenyl ether (DDE) (component B) (molar ratio (A / B) = 5/5) were charged at room temperature in a nitrogen atmosphere and dissolved.

  Subsequently, after thickening by polymerization reaction, the mixture was stirred at room temperature for 3 hours to obtain a carbon black-dispersed polyamic acid solution of 110 Pa · s (B-type viscometer, 25 ° C.).

<Method for producing semiconductive polyimide belt>
The solution was applied to a drum mold inner peripheral surface (stainless steel, surface roughness Rz = 0.3 μm) having an inner diameter of 300 mm and a length of 500 mm with a dispenser so that the final thickness was 400 μm.

  Next, the mold is fixed by rotating from both ends of the mold through the shaft fixed by the cone, and rotated at 2000 rpm for 15 minutes to obtain a uniform developed layer (coating surface). It was.

  Heat for 10 minutes while rotating the drum mold at 250 rpm in a drying oven at 100 ° C with evenly circulating hot air, then heat at 220 ° C for 10 minutes and the maximum heating temperature at 300 ° C for 30 minutes. By removing the solvent and the catalyst, imidization was advanced.

  The whole mold was cooled to room temperature, and then peeled off from the inner surface of the mold to obtain a 75 μm semiconductive polyimide belt.

<Comparative Example 1>
A belt was obtained according to Example 1 except that no catalyst was added.

<Comparative example 2>
A belt was obtained according to Example 1 except that the amount of the diamine component was 168 g of PDA and 77.8 g of DDE (A / B = 8/2).

<Comparative Example 3>
A belt was obtained in accordance with Example 1 except that the amount of the diamine component was 42 g PDA and 313.3 g DDE (A / B = 2/8).

<Comparative Example 4>
A belt was obtained in accordance with Example 1 except that a mold finished with a surface having a surface roughness Rz of 0.1 μm on the inner peripheral surface of the mold was used.

<Comparative Example 5>
A belt was obtained in accordance with Example 1 except that a mold finished with a surface having a surface roughness Rz of 1.2 μm on the inner peripheral surface of the mold was used.

<Comparative Example 6>
A belt was obtained according to Example 1, except that 50.2 g of isoquinoline as a catalyst and 396.9 g of acetic anhydride as a dehydrating agent were added to 2726 g of the dispersion, and then 1820 g of NMP was added.

<Evaluation test>
The following characteristics (evaluation items) were examined for the semiconductive belts obtained in Examples and Comparative Examples.

<Surface roughness Rz (ten-point surface roughness)>
In accordance with JIS B 0601 (1994), a sample was taken from an arbitrary 10 points on the outer peripheral surface of the belt, and with respect to the width direction, a cut-off of 0.25 mm with a surface roughness meter (Surf Test SJ-301, manufactured by Mitutoyo Corporation). The measurement length was 1.25 mm, the driving speed was 0.25 mm / sec, and the stylus load was 70 mg.

<Coefficient of surface dynamic friction>
Sampling was performed from 8 points of the obtained belt, and in each of the circumferential directions of the belt, a reciprocating friction tester (AFT-15B, manufactured by Orientec Co., Ltd.) was used. The dynamic friction coefficient under the condition of 150 mm / min was measured, and the average value was obtained.

<Surface resistivity>
The surface resistivity at 25 ° C. and 60% RH was measured with Hiresta UP MCP-HT450 (manufactured by Mitsubishi Oil Chemical Co., Ltd., probe: UR) under the measurement conditions of an applied voltage of 100 V and a value of 10 seconds.

<Image and belt drive>
The obtained belt was incorporated in a copying machine as a tandem intermediate transfer belt, and an image formation (printing) test using plain paper was performed. In addition, the evaluation is that the image having good image and belt drivability in the test of 100,000 sheets, ◯ having some image defect (printing defect) or drivability, and the image defect being visually recognizable or Those with drive failure were marked with x.

<Cleaning and crack resistance>
Throughout the image formation test, “Good” indicates good cleaning properties, “No” indicates toner remaining, and “No” indicates that the cleaning blade is turned up. Moreover, the thing which the crack generate | occur | produced in the belt during the test was set as x.

  From the results of Table 1, it was confirmed that good results were obtained for all the evaluation items in Example 1.

  On the other hand, in the comparative example, the image / belt drivability and the cleaning property were inferior to those of the example, and it was confirmed that the image after the printing test of 100,000 sheets had a fine print defect. In this regard, when the form of the belt surface was examined after the end of the printing test, there were continuous concave streaks and scratches, foreign objects and carriers, and there were fine concave scratches thought to be caused by local pressurization. A large number of toner components were formed, and it was confirmed that many toner components remained in this portion.

  In other words, the cleaning of the belt surface with the cleaning blade performed in a series of transfer processes does not remove the toner remaining in the concave flaws, but stagnates, resulting in an influence on the image at the next printing. It was.

  In Comparative Example 1 in which no catalyst was added, the image / belt drivability was poor.

  In Comparative Examples 2 and 3, since the molar ratio of the components A and B was outside the predetermined range, the surface friction coefficient, the image / belt drive performance, and the cleaning performance were poor. The reason for this is considered that Comparative Example 2 has high rigidity and causes cracking of the belt. Further, in Comparative Example 3, it is considered that the flexibility was large, the durability was not obtained, and the transfer target and the toner image could not be accurately conveyed.

  In Comparative Example 4, since the roughness of the belt surface was small, the frictional resistance between the belt surface and the blade was increased, and it was confirmed that the durability was inferior.

  In Comparative Example 5, since the belt surface was large in roughness, image deterioration (defect) was confirmed due to toner remaining at the initial printing test stage.

In Comparative Example 6, the reaction rapidly progressed due to the dehydrating agent, the gelation of the polyamic acid progressed, the coating became difficult, the belt surface was rough, and the deterioration (defective) of the image was confirmed.

Claims (4)

  A semiconductive polyimide belt containing a conductive filler, wherein the belt is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, p-phenylenediamine (component A) and 4,4′-. Including a copolymer obtained by polymerizing diaminodiphenyl ether (component B) in the presence of a catalyst and in the absence of a dehydrating agent, the molar ratio of component A to component B is (A / B) = 7 / 3-3 / 7 semiconductive polyimide belt. In the method for producing a semiconductive polyimide belt in which a tetracarboxylic acid component and a diamine component are dissolved and polymerized to obtain a copolymer in a dispersion in which a conductive filler is dispersed in a solvent.
In preparing the copolymer, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as the tetracarboxylic acid component, p-phenylenediamine (component A) and 4,4′-diamino as the diamine component Diphenyl ether (component B) is polymerized in a molar ratio of component A and component B (A / B) = 7/3 to 3/7 in the presence of a catalyst and in the absence of a dehydrating agent. A method for producing a conductive polyimide belt.   The surface dynamic friction coefficient using a steel ball of φ10 mm on the outer peripheral surface of the belt is 0.2 to 0.5, and the surface roughness Rz of the belt outer peripheral surface according to JIS B0601 (1994) is 0.2 to 1.0 μm. The semiconductive polyimide belt according to claim 1. 4. The semiconductive polyimide belt according to claim 1, comprising carbon black as the conductive filler and having a surface resistivity in the range of 1.0 × 10 ^{9 to} 1.0 × 10 ¹³ Ω / □.