JP2010261991A - Seamless belt and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seamless belt for printing beautiful (uniform) images without selecting paper concerning the seamless belt suitable for fixing, photoreceptor substrate, intermediate transfer, paper conveying, transfer fixing or the like in an electrophotographic image forming apparatus, and to provide a method for manufacturing the seamless belt. <P>SOLUTION: The seamless belt 100 includes an inner layer 1 including a polyimide resin, and an outer layer 2 including an elastomer. The method for manufacturing the seamless belt includes: a process (I) for deploying polyamic acid solution in the inner face of a cylindrical mold, and molding the inner layer 1 by heating and rotating the mold; and a process (II) for forming the outer layer 2 by deploying elastomer solution on the outer surface of the inner layer 1 obtained in the process (I). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a seamless belt. More specifically, the present invention relates to a seamless belt that can be suitably used for electrophotographic image forming apparatuses such as copying machines, laser beam printers, facsimiles, and composite apparatuses thereof. More specifically, the present invention relates to a seamless belt that can be particularly suitably used for fixing, photoreceptor substrate, intermediate transfer, paper transport, and transfer fixing in an electrophotographic image forming apparatus. The present invention further relates to a method for producing the seamless belt.

  In an electrophotographic image forming apparatus, generally, an electrostatic latent image corresponding to an image obtained by an image reading device is formed on the surface of a charged photoreceptor, and a toner image is formed by a developing device. It is electrostatically transferred (primary transfer) to an intermediate transfer member comprising a seamless belt, transferred again from the intermediate transfer member to paper or the like (secondary transfer), and heated and fixed by a fixing roll or a fixing belt. At this time, it has been studied to use a seamless belt not only for the intermediate transfer member but also for fixing that also serves as a photosensitive member and transfer.

  A seamless belt is usually manufactured by spreading a resin solution on the inner surface of a cylindrical mold, performing rotational molding and heat molding, and heating the mold by induction overheating (see, for example, Patent Document 1). ).

  Conventionally, a plastic material has been used as a material for a seamless belt because of its good moldability and light weight. In recent years, polyimide-based seamless belts using a polyimide resin have been studied because of excellent heat resistance, mechanical strength, and environmental resistance.

As a characteristic required for the belt material used for the electrostatic transfer system, the surface resistivity is about 10 ⁸ to 10 ¹³ Ω / □, that is, has a so-called medium resistance. In order to ensure such characteristics, in the case of a polyimide-based seamless belt, for example, a technique of containing a conductive filler such as carbon black in a polyimide resin is used (for example, see Patent Document 2).

  In recent years, the demand for higher image quality has been increasing year by year in the printer market. In other words, when performing solid printing using a conventional belt, a clear (uniform) image can be obtained with plain paper, but a clear (uniform) image can be printed with uneven paper such as embossed paper or Japanese paper. Cannot be done. This is considered to be caused by the fact that the toner cannot be uniformly transferred because the belt surface does not follow the unevenness of the paper. For this reason, it is necessary to develop a belt capable of printing a beautiful (uniform) image regardless of paper.

JP 2004-181731 A Japanese Patent Laid-Open No. 10-63115

  SUMMARY OF THE INVENTION An object of the present invention is a seamless belt suitable for fixing, photoreceptor base, intermediate transfer, paper transport and transfer fixing in an electrophotographic image forming apparatus. N) To provide a seamless belt capable of printing an image. Moreover, it is providing the method of manufacturing such a seamless belt.

The seamless belt of the present invention includes an inner layer containing a polyimide resin and an outer layer containing an elastomer.
In a preferred embodiment, the elastomer is at least one selected from a synthetic rubber and a thermoplastic elastomer.
In a preferred embodiment, the elastomer is a polystyrene-polyisoprene-polystyrene block copolymer.
In a preferred embodiment, the surface resistivity of the outer layer is a common logarithmic value of 6 to 13 (log Ω / □).
In a preferred embodiment, the volume resistivity of the entire seamless belt is a common logarithmic value of 7 to 12 (log Ω · cm).
In a preferred embodiment, the outer layer contains a conductive substance, and the content of the conductive substance is 30% by weight or less based on the total weight of the outer layer.
In another embodiment of the present invention, a method for producing a seamless belt is provided. The process for producing a seamless belt of the present invention comprises a step (I) of forming an inner layer by spreading a polyamic acid solution on the inner surface of a cylindrical mold, rotating the mold and heating, and the step (I). And (II) forming an outer layer by spreading an elastomer solution on the outer surface of the inner layer obtained in (1).
In a preferred embodiment, the elastomer solution contains at least one selected from a synthetic rubber and a thermoplastic elastomer.
In a preferred embodiment, the elastomer solution contains a polystyrene-polyisoprene-polystyrene block copolymer.
In a preferred embodiment, the elastomer solution contains a conductive material, and the content of the conductive material is 30% by weight or less based on the total weight of the elastomer in the elastomer solution.

  According to the present invention, a seamless belt suitable for fixing, photoconductor substrate, intermediate transfer, paper conveyance, transfer fixing, and the like in an electrophotographic image forming apparatus is used. N) A seamless belt capable of printing an image can be provided. Moreover, the method of manufacturing such a seamless belt can be provided.

It is a schematic sectional drawing of the seamless belt in preferable embodiment of this invention.

A. Overall Configuration of Seamless Belt The seamless belt of the present invention is a fixing belt, a photoreceptor substrate belt, an intermediate transfer belt, a paper conveying belt, and a transfer fixing belt in an electrophotographic image forming apparatus such as a copying machine or a printer. It is suitable for etc. The seamless belt of the present invention particularly preferably conveys a recording medium in an electrophotographic image forming apparatus. The recording medium is typically paper.

  FIG. 1 is a schematic cross-sectional view of a seamless belt according to a preferred embodiment of the present invention. The seamless belt 100 includes an inner layer 1 and an outer layer 2. The inner layer 1 includes a polyimide resin. The outer layer 2 includes an elastomer. In the present specification, the “outer layer” is a layer that forms the outermost periphery of the seamless belt, and refers to a layer on the side where a recording medium (typically paper) is conveyed. In the present specification, the “inner layer” refers to a layer on the side that does not contact the recording medium (typically paper) in the seamless belt, for example, a layer that contacts the roll for driving the seamless belt.

  By adjusting the surface resistivity of the outer layer, appropriate electrostatic adsorptivity can be obtained, and accumulation of residual charges due to continuous use during charging can be prevented. As a result, it is possible to obtain a seamless belt that can stably achieve both the adsorptivity and releasability of a recording medium (typically paper) and is excellent in cleaning properties and stain resistance. In a preferred embodiment, in the seamless belt of the present invention, the surface resistivity of the outer layer is a common logarithmic value of 6 to 13 (log Ω / □). The surface resistivity of the outer layer can be controlled, for example, by allowing the outer layer to contain a conductive substance and adjusting the type and content of the conductive substance.

  In the seamless belt of the present invention, any appropriate value can be adopted as the surface resistivity of the inner layer. In a preferred embodiment, considering the adjustment value of the surface resistivity of the outer layer so that the volume resistivity of the entire seamless belt of the present invention is 7 to 12 (log Ω · cm), the inner layer What is necessary is just to control surface resistivity.

  In a preferred embodiment, the volume resistivity of the entire seamless belt of the present invention is a common logarithmic value of 7 to 12 (log Ω · cm). More preferably, the volume resistivity is a common logarithmic value of 8 to 10 (log Ω · cm). If the volume resistivity of the entire seamless belt is in such a range, the recording medium (typically paper) has excellent adsorptivity and peelability, can suppress fluctuations in the speed of the seamless belt, and charge the seamless belt. Excellent uniformity and exfoliation discharge property. The volume resistivity of the entire seamless belt can be controlled, for example, by adjusting the type and content of the conductive material that may be included in the outer layer and the inner layer.

  The seamless belt of the present invention may further include any appropriate intermediate layer between the outer layer and the inner layer as long as the effects of the present invention are obtained.

B. Inner layer In the seamless belt of the present invention, the inner layer contains a polyimide resin.

  Any appropriate resin can be adopted as the polyimide resin. Examples of the polyimide resin include a copolymer of tetracarboxylic dianhydride or a derivative thereof and a diamine compound.

  Specific examples of the tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetra Carboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic 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) ) Ete Dianhydride, ethylene tetracarboxylic dianhydride, and the like.

  Specific examples of the diamine compound include p-phenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4 ′. -Diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-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-t-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-methylheptamethylene Diamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethyl To heptamethylenediamine, 3-methyl Ptamethylenediamine, 5-methylnonamethylenediamine, 2,11-diaminododecane, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 1,12 -Diaminooctadecane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane and the like.

  The polyimide resin is preferably an aromatic polyimide resin. If an aromatic polyimide resin is used, it is possible to obtain a transport belt having better heat resistance and mechanical strength. Specific examples of the aromatic polyimide resin include a copolymer of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-diaminodiphenyl ether (DDE), BPDA, and DDE. And a copolymer of p-phenylenediamine (PDA). The content ratio of the structural unit derived from PDA in the copolymer of BPDA, DDE and PDA is preferably 25 mol% or less with respect to the structural unit derived from DDE.

  In the seamless belt of the present invention, the inner layer may contain a conductive substance.

  Any appropriate material can be adopted as the conductive material. Specific examples of the conductive material include various carbons such as carbon black; various metals such as aluminum, nickel, silver and copper; various inorganic compounds such as tin oxide and potassium titanate; and conductive polymers such as polyaniline and polypyrrole. And the like. Carbon black is preferred from the viewpoints of suppressing variations in surface resistance, realizing low cost, and being easy to handle.

Any appropriate carbon black may be adopted depending on the desired conductivity. Specific examples of the carbon black include channel black, furnace black, ketjen black, and acetylene black. When antistatic properties are required in the middle to high resistance range (for example, surface resistivity 10 ⁸ to 10 ¹⁴ Ω / □, volume resistivity 10 ⁸ to 10 ¹⁴ Ω · cm), channel black or furnace black Are preferably used. The carbon black may be subjected to a treatment such as an oxidation treatment or a graft treatment depending on the application. If oxidation treatment is performed, oxidative deterioration can be prevented, and if graft treatment is performed, dispersibility in a solvent can be improved.

  A commercial product may be used as the carbon black. As specific examples of commercially available channel black, trade names “Color Black FW200”, “Color Black FW2”, “Color Black FW2V”, “Color Black FW1”, “Color Black FW18” manufactured by Degussa Huls, “Special Black 6”, “Color Black S170”, “Color Black S160”, “Special Black 5”, “Special Black 4”, “Special Black 4A”, “Printex 150T”, “Printex P” "Printex 140U", "Printex 140V", etc. are mentioned. As specific examples of commercially available furnace black, trade names “Special Black 550”, “Special Black 350”, “Special Black 250”, “Special Black 100”, “Printex 35”, and “Printex 35” manufactured by Degussa Huls. “25”, trade names “MA 7”, “MA 77”, “MA 8”, “MA 11”, “MA 100”, “MA 100R”, “MA 220”, “MA 230”, manufactured by Mitsubishi Chemical Corporation, “MONARCH 1300”, “MONARCH 1100”, “MONARCH 1000”, “MONARCH 900”, “MONARCH 880”, “MONARCH 800”, “MONARCH 700”, “MOGUL L”, “REG” manufactured by Cabot Corporation AL 400R "," VULCAN XC-72R "and the like.

  In the inner layer, the content ratio of the conductive substance is preferably 3 to 40% by weight, more preferably 3 to 30% by weight with respect to the polyimide resin. If the content ratio of the conductive material is within such a range, a desired surface resistivity and volume resistivity can be obtained for the inner layer and the entire seamless belt of the present invention, and the seamless belt is excellent in mechanical strength. Can be obtained.

  The thickness of the inner layer is preferably 5 to 500 μm, more preferably 10 to 300 μm, still more preferably 20 to 200 μm, and particularly preferably 50 to 100 μm from the viewpoint of excellent mechanical properties such as strength and flexibility. It is.

  The surface resistivity of the inner layer is preferably a common logarithmic value of 6 to 13 (log Ω / □), and more preferably 6 to 12 (log Ω / □). If the surface resistivity of the inner layer is in such a range, accumulation of residual charges due to continuous use during charging can be prevented. As a result, it is possible to obtain a seamless belt that can stably achieve both the adsorptivity and releasability of a recording medium (typically paper) and is excellent in cleaning properties and stain resistance. The surface resistivity of the inner layer can be adjusted by, for example, the type and content of the conductive substance.

  The inner layer is prepared, for example, by (1) an organic solvent or a conductive substance dispersion by dispersing the conductive substance in an organic solvent, and (2) an organic solvent or a conductive substance dispersion. After the tetracarboxylic dianhydride or derivative thereof and the diamine compound are dissolved, a polymerization reaction is performed to prepare a polyamic acid solution. (3) After the polyamic acid solution is developed in a cylindrical mold, a ring-closing imide It can be obtained by making the reaction progress and forming the polyimide resin into a tubular shape.

  Any appropriate solvent can be adopted as the organic solvent. Specific examples of the organic solvent include acetone, chloroform, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, alcohol solvents (methanol, ethanol, isopropanol, etc.), N, N-dimethylformamide, N, N-dimethylacetamide, N, N. -Diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylenesulfone, dimethyltetramethylenesulfone, etc. . Of these, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, and N-methyl-2-pyrrolidone which are polar amide solvents are preferable. With these polar amide solvents, when a conductive material is used, a dispersion solvent for the conductive material and a polymerization reaction solvent in a subsequent step can be used together. In addition, low molecular weight N, N-dimethylformamide and N, N-dimethylacetamide can be easily removed from the polyamic acid and the polyamic acid molded article by evaporation, substitution or diffusion. The said organic solvent may be used independently and may be used in combination of 2 or more type.

  In the organic solvent, phenols such as cresol, phenol and xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like may be mixed singly or in combination.

  When the conductive material is used, a dispersant may be further added to the conductive material dispersion. If the conductive material contains a dispersant, the affinity between the conductive material and the organic solvent can be increased.

  Any appropriate dispersant can be adopted as the dispersant as long as the effects of the present invention can be obtained. Specific examples of the dispersant include poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylazide), poly (N-vinylformamide), poly (N-vinylacetamide), poly (N N-vinylphthalamide), poly (N-vinylsuccinamide), poly (N-vinylurea), poly (N-vinylpiperidone), poly (N-vinylcaprolactam), poly (N-vinyloxazoline), etc. Polymer dispersing agent; surfactant; inorganic salt; and the like. These dispersants may be used alone or in combination of two or more.

  When the conductive material is used, any appropriate dispersion method can be applied as a method for dispersing the conductive material. Examples of the dispersion method include a ball mill, a sand mill, a basket mill, a three-roll mill, a planetary mixer, a bead mill, and an ultrasonic dispersion method. Any appropriate method can be applied as a method for examining the dispersion state of the conductive substance. For example, the method of observing with an optical microscope is mentioned.

  In obtaining the inner layer, preferably, the tetracarboxylic dianhydride or derivative thereof and a diamine compound are dissolved in the organic solvent or the conductive material dispersion, and then a polymerization reaction is performed to obtain a polyamide. An acid solution is obtained. During the polymerization, a catalyst is preferably added. Any appropriate catalyst can be adopted as the catalyst. Specific examples of the catalyst include aliphatic tertiary amines, aromatic tertiary amines, and heterocyclic tertiary amines. Of these, nitrogen-containing heterocyclic compounds such as imidazole, benzimidazole, isoquinoline, quinoline, diethylpyridine, and β-picoline are preferable.

  The amount of the catalyst used is preferably 0.04 to 0.4 molar equivalent, more preferably 0.05 to 0.4 molar equivalent, relative to 1 molar equivalent of the amide acid in the polyamic acid precursor solution. If the addition amount of the catalyst is 0.04 equivalent mole or less, the effect of the catalyst may not be sufficient. Moreover, even if the addition amount of the catalyst is 0.4 equivalent or more, there is a possibility that the improvement effect of the catalyst addition is not seen.

  The monomer concentration (concentration of tetracarboxylic dianhydride component and diamine component in the solvent) during the polymerization reaction is preferably 5 to 30% by weight.

  The reaction temperature during the polymerization reaction is preferably 80 ° C. or lower, and more preferably 5 to 50 ° C. The reaction time is preferably 5 to 10 hours.

  The solution viscosity of the polyamic acid solution is preferably 1 to 1000 Pa · s (25 ° C.) with a B-type viscometer. If the solution viscosity is in such a range, the solution can be uniformly developed at the time of centrifugal molding in the next step, and a seamless belt having a uniform thickness can be obtained. The solution viscosity of the polyamic acid solution can be set to a desired viscosity by further heating and stirring the polyamic acid solution obtained after the polymerization reaction. The heating temperature is preferably 50 to 90 ° C.

  In obtaining the inner layer, preferably, the polyamic acid solution is developed in a cylindrical mold, and then the ring-closing imidization reaction is advanced to form a polyimide resin in a tubular shape. By molding the polyimide resin into a tubular shape, it is possible to obtain an inner layer of a seamless belt that does not have a joining portion (joining portion generated when the film is tubular). As a result, a seamless belt having excellent durability and circumference accuracy can be obtained. Examples of the method of developing in the cylindrical mold include a dispenser coating method, a dipping method, a centrifugal method, and a method of filling a casting mold. Preferably, a centrifugal method in which the inner peripheral surface of the mold is developed by a centrifugal force by a rotational centrifugal molding method is used. According to such a method, the polyamic acid solution can be uniformly developed. The ring-closing imidization reaction can proceed by heating the developed polyamic acid solution. The heating temperature at this time is preferably 300 to 400 ° C. The heating time at this time is preferably 0.5 to 1 hour. The heating method is preferably a method of heating while rotating the mold, a method of using high-precision hot air circulation, a method of charging at a low temperature to reduce the temperature rising rate, and a combination of these methods. According to such a heating method, the polyamic acid solution and the dried product can be uniformly heated. As a result, the surface resistivity of the inner layer and the volume resistivity of the entire seamless belt can be made uniform.

C. Intermediate Layer The seamless belt of the present invention may have any appropriate intermediate layer between the inner layer and the outer layer as necessary. Examples of the intermediate layer include a conductive primer layer. If the conductive primer layer is provided as the intermediate layer, the adhesion between the outer layer and the inner layer can be improved. Examples of the conductive primer include a conductive fluorine-based primer and a conductive polyimide-based primer.

  The thickness of the intermediate layer is preferably 0.3 to 5 μm, more preferably 0.5 to 2 μm.

  The intermediate layer can be formed by any appropriate method. For example, when the intermediate layer is a conductive primer layer, it can be obtained by applying a primer solution to the outer peripheral surface of the inner layer. Examples of the application method include roll coating, brush coating, and spray coating.

D. Outer layer In the seamless belt of the present invention, the outer layer includes an elastomer.

  Any appropriate elastomer can be adopted as the elastomer. As is generally known, an elastomer is a high-molecular substance exhibiting elasticity, and has a mechanical property (rubber elasticity) that is easily changed by an external force, but almost recovers to its original shape immediately after removing it.

  Examples of the elastomer include vulcanized rubber such as natural rubber and synthetic rubber; thermoplastic elastomer; elastic fiber such as spandex and polycarbonate elastic fiber; and elastic foam such as sponge rubber and foam rubber. In the present invention, it is preferable to employ at least one selected from synthetic rubber and thermoplastic elastomer as the elastomer.

  Examples of the synthetic rubber include styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR), ethylene-propylene rubber (EPM, EPDM), and acrylonitrile-butadiene rubber (NBR). , Chloroprene rubber (CR), acrylic rubber (ACM, ANM), epichlorohydrin rubber (CO, ECO, GECO, GPCO), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), urethane rubber (U), fluoro rubber (FKM, FEPM, FFKM), silicone rubber (MQ, PMQ), polysulfide rubber (OT, EOT), phosphazene rubber (FZ, PZ) and the like.

  The thermoplastic elastomer is a polymer material that exhibits properties of vulcanized rubber at room temperature, is plasticized at high temperature, and can be molded by a plastic processing machine, and is referred to as TPE. Examples of the thermoplastic elastomer include polystyrene TPE, polyolefin TPE, polyester TPE, polyurethane TPE, 1,2-polybutadiene TPE, polyvinyl chloride TPE, polyamide TPE, and the like.

  In the present invention, the elastomer is preferably an elastomer obtained without requiring a curing reaction, and more preferably a polystyrene-polyisoprene-polystyrene block copolymer (SIS). In the seamless belt of the present invention, when the outer layer contains SIS, it becomes easy to appropriately control the surface resistivity of the outer layer, appropriate electrostatic adsorption can be obtained, and accumulation of residual charges by continuous use during charging. Can be prevented. As a result, it is possible to obtain a seamless belt that can stably achieve both the adsorptivity and releasability of a recording medium (typically paper) and is excellent in cleaning properties and stain resistance.

  In the seamless belt of the present invention, the outer layer preferably contains a conductive substance. Any appropriate material can be adopted as the conductive material. Specific examples of the conductive material include those that can be used for the inner layer described above. Carbon black is preferred from the viewpoints of suppressing variations in surface resistance, realizing low cost, and being easy to handle.

  In the outer layer, the content of the conductive substance is preferably 30% by weight or less, more preferably 1 to 30% by weight, and still more preferably 5 to 25% by weight with respect to the total weight of the outer layer. If the content ratio of the conductive material is in such a range, the desired surface resistivity and volume resistivity can be obtained for the outer layer and the entire seamless belt of the present invention, and the seamless belt is excellent in mechanical strength. Can be obtained.

  The thickness of the outer layer is preferably 5 to 500 μm, more preferably 10 to 300 μm, still more preferably 20 to 200 μm, and particularly preferably 50 to 100 μm from the viewpoint of excellent mechanical properties such as strength and flexibility. It is.

  When the outer layer is obtained, the outer layer is preferably formed by spreading the elastomer solution (elastomer solution) on the outer surface of the inner layer. The elastomer solution may be one in which the elastomer itself is in solution or may be one dissolved in the above organic solvent. By developing the elastomer solution on the outer surface of the inner layer, it is possible to obtain an outer layer of a seamless belt that does not have a joint (joint formed when the film is tubular). As a result, a seamless belt having excellent durability and circumference accuracy can be obtained. Examples of the developing method include a dispenser coating method, a dipping method, and a spray method.

  The method of spreading the elastomer solution on the outer surface of the inner layer preferably includes a step of applying the elastomer solution to the outer surface of the inner layer, and a step of drying and heating after the application.

  Examples of the method for applying the elastomer solution include spray coating, spin coating, roll coating, brush coating, and the like.

As the gun used for the spray coating, a gun having a small nozzle diameter is preferable because uniform application is possible. The nozzle diameter is preferably 0.1 to 2.0 mm. The spray pressure during the spray coating is preferably 1.0 to 5.0 kg / cm ² .

  When applying the elastomer solution, a cylinder for maintaining the shape may be inserted inside the inner layer. In addition, a cylindrical body is extrapolated to the inner layer to which the elastomer solution is applied, and from this state, the cylindrical body or the inner layer is caused to travel in the axial direction of the cylindrical body, or both are caused to travel in opposite directions. The coating thickness may be made uniform.

  The heating temperature after applying the elastomer solution is preferably 20 to 200 ° C, more preferably 80 to 150 ° C. The heating time during the heating is preferably 1 minute to 24 hours.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, parts and% in the examples are based on weight (mass).

[Surface resistivity, volume resistivity]
UP MCP-HT450 (manufactured by Mitsubishi Chemical Corporation, probe: UR) is used as the Hiresta, and the applied voltage is 500V (note that the measured value is lower than the common logarithmic value of 8.0 or lower, so the voltage is lowered and measured at the applied voltage of 10V), The surface resistivity and volume resistivity at 25 ° C. and 60% RH were measured under the measurement conditions for 10 seconds. The measurement was performed at 12 points on the surface of the seamless belt, and the average value was shown as a common logarithmic value.

[Belt appearance evaluation]
The appearance of the seamless belt was visually evaluated.

[Image evaluation]
A seamless belt as an intermediate transfer belt was set on a color printer (manufactured by Ricoh Co., Ltd., MP C2500), and printing was performed on Japanese paper (manufactured by NBS Ricoh Co., Ltd.).

[Example 1]
(Formation of inner layer)
In 3000 g of N-methyl-2-pyrrolidone (NMP), dried carbon black (Printex V, manufactured by Degussa Japan, volatile content: 5%, BET specific surface area: 100 m ² / g, volatile content / BET specific surface area × 100: 5%, pH 4.5, no oxidation treatment) 140.2 g (23% by weight based on polyimide) was mixed with a ball mill for 6 hours (room temperature).
In this carbon black-dispersed NMP, 489.8 g of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BPDA) and 179.9 g of p-phenylenediamine (PDA) were dissolved, and in a nitrogen atmosphere, The reaction was performed with stirring at room temperature for 6 hours to obtain a 150 Pa · s carbon black-dispersed polyamic acid solution.
The solution was applied to the inner surface of a cylindrical mold (made of SUS) having an inner diameter of 300 mm and a length of 900 mm with a dispenser to a thickness of 170 μm, and then rotated at 1500 rpm for 10 minutes to obtain a uniform coated surface. Next, while rotating at 20 rpm, hot air of 130 ° C. was applied for 30 minutes from the outside of the mold, and then heated to 350 ° C. at a rate of 4 ° C./min and held at 350 ° C. for 15 minutes. After cooling, the belt was released from the inner surface of the mold to obtain a 75 μm polyimide resin belt.
(Formation of outer layer: manufacture of seamless belt (1))
A SIS (Quintac 3530, manufactured by Nippon Zeon Co., Ltd.) added with 15 parts of carbon black (MHI black, manufactured by Mikuni Dye Co., Ltd.) is added to the outer layer of the polyimide resin belt as the inner layer, and the total thickness after drying is 250 μm. Then, the coating was performed, and the temperature was raised to 130 ° C. and dried for 15 minutes to produce a seamless belt (1).
Various evaluation was performed about the obtained seamless belt (1). The results are shown in Table 1.

[Comparative Example 1]
A seamless belt (C1) was produced in the same manner as in Example 1 except that the outer layer was not formed.
Various evaluation was performed about the obtained seamless belt (C1). The results are shown in Table 1.

[Comparative Example 2]
For the formation of the outer layer, instead of using SIS (Quintac 3530, manufactured by Nippon Zeon Co., Ltd.) with 15 parts of carbon black (MHI black, manufactured by Mikuni Dye Co., Ltd.), an addition reaction type silicone rubber (SH1850, Toray Dow Corning) A seamless belt (C2) was produced by curing at room temperature using a product obtained by adding 15 parts of carbon black (MHI Black, produced by Mikuni Dye Co., Ltd.) to Silicone.
Various evaluation was performed about the obtained seamless belt (C2). The results are shown in Table 1.

  As is clear from Table 1, when the seamless belt of the present invention is used, it is possible to print a beautiful (uniform) image regardless of the paper.

  The seamless belt of the present invention is suitable for a fixing belt, a photoreceptor substrate belt, an intermediate transfer belt, a paper conveying belt, a transfer fixing belt, and the like in an electrophotographic image forming apparatus such as a copying machine or a printer. .

1 Inner layer 2 Outer layer

Claims (10)

  A seamless belt comprising an inner layer containing a polyimide resin and an outer layer containing an elastomer.   The seamless belt according to claim 1, wherein the elastomer is at least one selected from a synthetic rubber and a thermoplastic elastomer.   The seamless belt according to claim 2, wherein the elastomer is a polystyrene-polyisoprene-polystyrene block copolymer.   The seamless belt according to any one of claims 1 to 3, wherein the surface resistivity of the outer layer is a common logarithm of 6 to 13 (log Ω / □).   The seamless belt according to any one of claims 1 to 4, wherein the volume resistivity of the entire seamless belt is a common logarithm of 7 to 12 (log Ω · cm).   The seamless belt according to any one of claims 1 to 5, wherein the outer layer includes a conductive substance, and a content ratio of the conductive substance is 30% by weight or less based on a total weight of the outer layer. (1) forming the inner layer by spreading the polyamic acid solution on the inner surface of the cylindrical mold and rotating the mold to heat;
A step (II) of forming an outer layer by spreading an elastomer solution on the outer surface of the inner layer obtained in the step (I);
A method for producing a seamless belt, comprising:   The production method according to claim 7, wherein the elastomer solution contains at least one selected from a synthetic rubber and a thermoplastic elastomer.   The manufacturing method according to claim 8, wherein the elastomer solution contains a polystyrene-polyisoprene-polystyrene block copolymer. The production according to any one of claims 7 to 9, wherein the elastomer solution contains a conductive substance, and a content ratio of the conductive substance is 30% by weight or less based on a total weight of the elastomer in the elastomer solution. Method.

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