JP2007176160A - Multilayer polyimide tubular object and its manufacturing process, and manufacturing equipment of resin tubular object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer polyimide tubular object, which can achieve speeding up, miniaturization, weight saving of a printer, etc. <P>SOLUTION: The multilayer polyimide tubular object of the present invention is equipped with a first polyimide resin layer, a second polyimide resin layer and a mixed polyimide resin layer. The first polyimide resin layer consists of a first polyimide resin. The second polyimide resin layer consists of a second polyimide resin. The first polyimide resin corresponding with the first polyimide resin layer and the second polyimide resin corresponding with the second polyimide resin layer intermingle in the mixed polyimide resin layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multilayer polyimide tubular article suitably used for a member of an electrophotographic image forming apparatus such as a copying machine or a printer, or a medical tube, a method for producing the same, and an apparatus for producing a resin tubular article.

  Polyimide has excellent properties such as heat resistance, dimensional stability and mechanical properties. For this reason, it is used in many applications as a member for image formation, transfer, and fixing processes in electrophotographic image forming apparatuses such as copying machines and laser beam printers, as a belt for thermal laminators, medical catheters, and endoscope tubes. Has been. Hereinafter, a polyimide tubular material used as a transfer belt and a fixing belt of a copying machine or a laser beam printer will be described with examples.

  In an image forming apparatus such as a color laser printer using electrophotographic technology, as shown in FIG. 1, an image is formed on the surface of the photosensitive drum 23 with toners of basic colors (yellow, magenta, cyan, and black). Thereafter, the toner image is once transferred onto the intermediate transfer belt 21, further transferred again to the copy paper 25, and then thermally fixed by the fixing device 26. Such a system is called an intermediate transfer belt system and is widely used in the world. In the electrophotographic image forming apparatus shown in FIG. 1, the polyimide tubular material is used as the intermediate transfer belt 21, the photosensitive drum 23, and the fixing belt 26. In FIG. 1, reference numeral 22 denotes a belt pulley, and reference numeral 24 denotes an exposure scanning device.

Incidentally, the intermediate transfer belt 21 has a charging characteristic in which the surface is electrostatically charged and electrostatically attracts the toner image on the photosensitive drum, and a charging characteristic in which the surface is neutralized and the toner image is retransferred onto the copy paper. It is required to have anti-static properties that are contrary to the above. For this reason, surface resistivity or volume resistivity is an important characteristic in the intermediate transfer belt, and precise control of each resistivity is required. In order to satisfy such a requirement, the first thermosetting polyimide resin layer having a surface electrical resistance value of 10 ⁹ Ω / □ to 10 ¹³ Ω / □ in the past and the back side of the first thermosetting polyimide resin layer And a second thermosetting polyimide resin layer having a surface electric resistance value larger than the surface electric resistance value of the first thermosetting polyimide resin layer and having a volume electric resistance value of the first thermosetting polyimide resin. A “polyimide tubular product” that is smaller than the surface electrical resistance value of the layer has been proposed (for example, see Patent Document 1). In addition, such a polyimide tubular body is formed by, for example, forming two types of polyimide precursors containing an appropriate amount of a conductive substance into a two-layer structure by centrifugal molding, and then forming a first thermosetting polyimide resin layer and a second layer. It is manufactured by simultaneously ring-closing imidization with a thermosetting polyimide resin layer (see Patent Document 1). More specifically, in this method for manufacturing a polyimide tubular product, first, the raw material of the first thermosetting polyimide resin layer is put into a cylinder of a centrifugal molding device, and then the centrifugal molding device is driven to rotate. When the centrifugal molding apparatus is driven to rotate, the entire thickness of the raw material of the first thermosetting polyimide resin layer is made uniform over time in the centrifugal molding apparatus. And external heating is started from the time of thinking that the whole thickness of the raw material of a 1st thermosetting polyimide resin layer was fully equalized, and the raw material of a 1st thermosetting polyimide resin layer is finally 100- Heat at 120 degrees C for about 30 minutes. Thereafter, the raw material of the first thermosetting polyimide resin layer is cooled, and the rotation of the centrifugal molding device is stopped. Subsequently, the raw material of the second thermosetting polyimide resin layer is applied, heated, and cooled under the same conditions. The polyimide precursor tubular product obtained in this way is peeled off from the centrifugal molding device, inserted into the core body, and then put into another heating device. It becomes.

  Further, in recent years, a film fixing method shown in FIG. 2 has been mainly used as a method for thermally fixing a toner image re-transferred from an intermediate transfer belt onto a copy sheet. For example, a method or apparatus disclosed in Patent Document 2 is used. It is often used. In this film fixing method, printing can be performed without waiting after the power is turned on, and since a thin polyimide tubular material is used, power consumption is low. For this reason, this film fixing method is accepted by people all over the world as an environmentally friendly fixing method. The fixing device shown in FIG. 2 mainly includes a fixing belt 1 (polyimide tubular material), a belt guide 2 disposed inside the fixing belt 1, and a ceramic heater 3 disposed near the center of the belt guide 2. The thermistor 5 installed on the ceramic heater 3 and the pressure roller 4 are provided. In this fixing device, when the copy paper 7 on which the toner image is formed is sequentially fed between the pressure roller 4 brought into pressure contact with the ceramic heater 3 via the fixing belt 1, the toner is heated and melted. To be fixed on the copy paper. In FIG. 2, reference numeral 9 denotes a fixed toner, reference numeral 6 denotes a cored bar portion of the pressure roller, and N denotes a nip surface between the fixing belt 1 and the pressure roller 4.

  In the film fixing method, it is necessary to heat-fix the toner on the copy paper in as short a time as possible. Therefore, the toner must be heat-fixed by efficiently using the amount of heat generated by the ceramic heater 3. For this reason, when the film fixing method is adopted, the fixing belt 1 is required to have high thermal conductivity. In response to such demands, the applicant of the present application has proposed to employ a polyimide resin in which thermally conductive fine particles such as boron nitride are uniformly dispersed as a raw material for a seamless polyimide film (fixing belt) ( (See Patent Document 3).

  By the way, a photosensitive drum made of a polyimide tubular material indicated by reference numeral 23 in FIG. 1 is required for a technique called a back exposure method developed to cope with a reduction in size or weight of a printer. In this back exposure method, an image forming process such as charging, exposure, development, and transfer is performed in a state where the optical scanning system is housed inside the photosensitive drum. This technology is expected to reduce the size, weight, and cost of electrophotographic image forming apparatuses. In this method, since the optical scanning system is arranged inside the photosensitive drum 23 (polyimide tubular material) as described above, the photosensitive drum 23 has light transmission properties, mechanical characteristics, smoothness of the outer surface, and the like. Characteristics are required. As such a photosensitive drum, a photosensitive drum using a polyimide resin that transmits 85% or more of light having a wavelength of 660 nm has been proposed (see, for example, Patent Document 4).

In addition, as a method of manufacturing the above-described fixing belt, intermediate transfer belt, and photosensitive drum, the present applicant applies a polyimide precursor solution to the outer surface of the core body, and then sets a predetermined inner diameter along the outer surface of the core body. The outer die is held, a polyimide precursor film having a predetermined thickness is formed on the surface of the core, imidized by means such as heating, and then the mold and the core are separated to obtain a polyimide tubular product. A method has been proposed (for example, see Patent Document 5).
JP 2004-29769 A JP-A-6-258969 JP 7-186162 A JP-A-5-249705 JP 7-178741 A

  However, in the conventional manufacturing technology, the basic characteristics such as the electrical resistivity, thermal conductivity, and light transmission required for the intermediate transfer belt, the fixing belt, or the photosensitive drum, and the mechanical characteristics or the surface smoothness are described. It is extremely difficult to obtain a polyimide tubular product having general characteristics such as properties.

  For example, in the production method according to Patent Document 1, it is possible to produce a polyimide tubular product by differentiating the raw material of the first thermosetting polyimide resin layer and the raw material of the second thermosetting polyimide resin layer, It is necessary to repeat the process of forming the thermosetting polyimide resin layer raw material individually with a centrifugal molding device, heating it to the intermediate stage of imidization and then cooling it, and thereafter, from the centrifugal molding device to the polyimide precursor tube This is very complicated because it is necessary to take out the product, insert the core into the polyimide precursor tubular product, and perform the final imidization treatment. For this reason, it cannot be said that such a manufacturing method is unsuitable for industrial production. In addition, this manufacturing method is a manufacturing method in which the polyimide precursor solution is centrifuged and then heated to stop the imidization reaction of the first layer at an intermediate stage, and then the second layer is laminated. If the imidization reaction of the polyimide precursor tubular product to be progressed excessively, the interlayer adhesive force between the first thermosetting polyimide resin layer and the second thermosetting polyimide resin layer may be reduced. Further, this manufacturing method has many problems such as difficulty in manufacturing a tubular product having a small inner diameter.

  Further, in the manufacturing method according to Patent Document 3, although the thermal conductivity can be improved, the mechanical characteristics are reduced in inverse proportion, and problems such as buckling of the fixing belt and tearing from the end portion are newly generated. For this reason, it is necessary to balance the mechanical properties and thermal conductivity (mixing ratio of thermally conductive fine particles) of the polyimide tubular material. Therefore, there has been no choice but to compromise the speed of the electrophotographic image forming apparatus.

  In addition, since a polyimide tubular material used as a back exposure photosensitive drum requires high light transmittance, 2,2-bis [4- (dicarboxyphenoxy) is used as an acid dianhydride component in polymerization of a polyimide precursor. Phenyl] propane dianhydride (BPADA), 2,2-bis (4-carboxyphenyl) hexafluoropropane dianhydride (6FDA) and the like are 4,4′-diaminodiphenylsulfone (44DDS) and bis [ 4- (3-Aminophenoxy) phenyl] sulfone (BAPSM) or the like needs to be used. However, the transparent polyimide obtained from such a polyimide precursor has extremely low mechanical properties, and it is almost impossible to achieve both light transmittance and mechanical properties.

  Moreover, in order to manufacture a multilayer polyimide tubular product using the manufacturing method according to Patent Document 5, first, after forming a polyimide precursor solution, heating and processing until the polyimide coating is in a semi-cured state , The previous process needs to be repeated once more. As described above, the manufacturing process becomes complicated and the number of manufacturing processes increases, so that there is a possibility that foreign matters are mixed and defects are increased. In addition, when a polyimide precursor solution is laminated on the surface of a semi-cured polyimide film, problems such as repellency and dripping of the polyimide precursor solution are likely to occur, and the adhesive force between two layers becomes unstable. Problems may arise.

  An object of the present invention is to provide a multilayer polyimide tubular article that can solve the above-described conventional problems and can realize speeding up, downsizing, and weight reduction of an electrophotographic image forming apparatus. Another object of the present invention is to provide a method and an apparatus for producing a multilayer polyimide tubular product capable of producing such a multilayer polyimide annular product while keeping the production cost low.

  The multilayer polyimide tubular product according to the present invention includes a first polyimide resin layer, a second polyimide resin layer, and a polyimide resin mixed layer. The first polyimide resin layer is made of a first polyimide resin. The second polyimide resin layer is made of a second polyimide resin. In the polyimide resin mixed layer, a first polyimide resin continuous with the first polyimide resin layer and a second polyimide resin continuous with the second polyimide resin layer are mixed.

  In the multilayer polyimide tubular product according to the present invention, at least one of the first polyimide resin layer and the second polyimide resin layer is selected from the group consisting of conductive particles, thermally conductive particles, and fluororesin particles. It may contain at least one particle.

  Moreover, in the multilayer polyimide tubular product according to the present invention, the first polyimide resin layer and the second polyimide resin layer are made of a polyimide precursor obtained by polymerizing an aromatic tetracarboxylic acid anhydride and an aromatic diamine in an organic polar solvent. It may be imidized.

  In the multilayer polyimide tubular product according to the present invention, at least one of the inner surface and the outer surface may be covered with a release layer.

  The method for producing a multilayer polyimide tubular product according to the present invention includes a polyimide precursor solution overcoating step and an imidization step. In the polyimide precursor solution overcoating step, the first polyimide precursor solution and the second polyimide precursor solution are applied in an overlapping manner on the outer surface of the core body. Here, the “first polyimide precursor solution” is a solution of the first polyimide precursor. The “second polyimide precursor solution” referred to here is a solution of the second polyimide precursor. In the imidization step, the solvent is removed from the first polyimide precursor solution and the second polyimide precursor solution, and the first polyimide precursor and the second polyimide precursor are imidized.

  In order to be able to use this multilayer polyimide tubular product as a fixing belt, an intermediate transfer belt, etc., in the imidization step, at least the first polyimide precursor and the second polyimide can be maintained until the strength as the tubular product can be maintained. After treating the precursor to prepare a semi-cured polyimide tubular material, a conductive primer is applied to the outer surface of the semi-cured polyimide tubular material and dried, followed by coating with a fluororesin and heating it. It is preferable to simultaneously perform the imidization reaction completion treatment and the fluororesin baking treatment by the treatment.

  And if this manufacturing method is implemented using the manufacturing apparatus which concerns on this invention introduced next, it can be implemented efficiently.

  An apparatus for producing a multilayer resin tubular product according to the present invention includes a first cylindrical wall, a second cylindrical wall, a solution delivery unit such as a first resin, and a solution delivery unit such as a second resin. The inner diameters of the first cylindrical wall and the second cylindrical wall are designed so that a columnar or cylindrical core can pass through with a predetermined gap. In addition, the “resin solution delivery unit” referred to here is a pressurizer, a pump, or the like. The first cylindrical wall has an opening. In the first cylindrical wall, the openings may be formed by removing a part of the cylindrical portion, or a plurality of openings may be formed uniformly over the entire circumference. The second cylindrical wall has an opening. In the second cylindrical wall, the openings may be formed by removing a part of the cylindrical portion, or a plurality of openings may be formed uniformly over the entire circumference. Further, the inner peripheral diameter of the second cylindrical wall is smaller than the inner peripheral diameter of the first cylindrical wall. And this 2nd cylindrical wall is arrange | positioned under the 1st cylindrical wall so that an axis | shaft may follow the axis | shaft of a 1st cylindrical wall. The first resin solution delivery unit delivers the first resin solution or the first resin precursor solution to the opening of the first cylindrical wall. The second resin solution delivery unit delivers the second resin solution or the second resin precursor solution to the opening of the second cylindrical wall. The resin solution delivery unit may deliver the resin solution or the resin precursor solution directly to the opening of the cylindrical wall (for example, a pipe extending from the resin storage tank is directly connected to the opening of the cylindrical wall. Or the like, the resin solution or the resin precursor solution may be delivered once to a resin pool provided in front of the opening of the cylindrical wall or the like and indirectly delivered to the opening of the cylindrical wall.

  In this multilayer resin tubular product manufacturing apparatus, the first resin solution delivery section and the second resin solution delivery section use the first resin solution or the second cylinder wall opening at a predetermined discharge speed from the opening of the first cylindrical wall and the opening of the second cylindrical wall. In a state where the first resin precursor solution and the second resin solution or the second resin precursor solution are discharged, the columnar or cylindrical core is first along the axis of the first cylindrical wall and the second cylindrical wall. When passing through the cylindrical wall and the second cylindrical wall, a solution tubular coating such as a two-layer resin having a predetermined thickness is formed on the core. As a method of passing the core body through the first cylindrical wall and the second cylindrical wall along the axes of the first cylindrical wall and the second cylindrical wall, the first cylindrical wall and the second cylindrical wall are fixed, and the core body A method of pulling up the core body at a predetermined speed via a hanging strap attached to the shaft end of the shaft, or a method of fixing the core body and moving the first cylindrical wall and the second cylindrical wall along the core body at a predetermined speed Etc. are considered.

  In addition, it is preferable that this multilayer resin tubular product manufacturing apparatus further includes a delivery timing control mechanism. The delivery timing control mechanism is configured to deliver the first resin solution or the first resin precursor solution to the opening of the first cylindrical wall by the first resin solution delivery unit and the second resin solution or second resin by the second resin solution delivery unit. 2 Delay the delivery of the resin precursor solution to the opening of the second cylindrical wall. As the delivery timing control mechanism, for example, a mechanism composed of two motor-operated valves and a control device capable of independently controlling the opening timing of the motor-operated valves is conceivable. In this case, when the core passes through the first cylindrical wall after passing through the second cylindrical wall, the first resin solution or the first resin precursor solution is lowered when the discharge of the resin solution or the resin precursor solution starts. It is possible to avoid dripping and mixing with the second resin solution or the second resin precursor solution.

  In the multilayer polyimide tubular product according to the present invention, a polyimide resin mixed layer in which a first polyimide resin continuous with the first polyimide resin layer and a second polyimide resin continuous with the second polyimide resin layer are mixed is formed. . For this reason, in this multilayer polyimide tubular product, the first polyimide resin layer and the second polyimide resin layer are firmly integrated. For this reason, this multilayer polyimide tubular product is practically free from problems such as peeling. Therefore, this multilayer polyimide tubular product can exhibit sufficient characteristics as a transfer belt, a fixing belt, a photosensitive drum or the like of an electrophotographic image forming apparatus.

  In addition, in the multilayer polyimide tubular product according to the present invention, when functional particles are mixed in a certain polyimide resin layer, negative elements of the polyimide resin layer (decrease in mechanical properties, decrease in surface smoothness, etc.) Is supplemented by another polyimide resin layer, and when functional particles are mixed in two adjacent polyimide resin layers, the negative elements of these polyimide resin layers (decrease in mechanical properties and surface smoothness) Will be compensated for each other). In other words, this multilayer polyimide tubular product can have characteristics such as thermal conductivity, electrostatic characteristics, or light transmittance, and mechanical characteristics inherent in polyimide.

  Moreover, in the manufacturing method of the multilayer polyimide tubular body which concerns on this invention, a 1st polyimide precursor solution and a 2nd polyimide precursor solution are piled up and apply | coated to the outer surface of a core body in a polyimide precursor solution recoating process. That is, in this manufacturing method, the coating process of the polyimide precursor solution is made into one process. For this reason, in this manufacturing method, a part of polyimide precursor solution adjacent to each other can be mixed. Then, in the imidization process, when two adjacent polyimide precursor solution layers in which a part is mixed are removed and imidized, the first polyimide resin and the second polyimide are formed at the boundary portion. A polyimide resin mixed layer in which the resin and the resin are intertwined with each other is formed. For this reason, in this production method, a multilayer polyimide tubular product can be produced without removing any polyimide precursor tubular product or the like from the core until the imidization step is completed. Therefore, if this manufacturing method is used, the processing steps can be greatly simplified and shortened as compared with the conventional manufacturing method. That is, a multilayer polyimide tubular product can be produced at a production cost lower than that of a conventional production method. Further, in the production method according to the present invention, a polyimide precursor solution is adopted as a raw material for the multilayer polyimide tubular material. Therefore, conductive fine particles, heat conductive fine particles, fluororesin particles, etc. are mixed in advance with the polyimide precursor solution. I can leave. For this reason, if this manufacturing method is utilized, the precision of mixing and dispersion | distribution of the microparticles | fine-particles in a polyimide resin layer can be improved, and a high quality multilayer polyimide tubular thing can be manufactured.

  In the multilayer resin tubular product manufacturing apparatus according to the present invention, the first resin solution or first resin precursor solution and the second resin solution or second resin solution delivery unit and the second resin solution delivery unit are used. Two resin precursor solutions are delivered to the opening of the first cylindrical wall and the opening of the second cylindrical wall. For this reason, in this multilayer resin tubular product manufacturing apparatus, a new resin solution or resin precursor solution can always be applied to the core. Therefore, in this multilayer resin tubular product manufacturing apparatus, the resin solution or the resin precursor solution does not contain foreign matters or bubbles, and a high-quality multilayer resin tubular product can be manufactured with a high yield. In addition, when the multilayer resin tubular product manufacturing apparatus further includes a delivery timing control mechanism and the core passes through the first cylindrical wall after passing through the second cylindrical wall, discharge of the resin solution or resin precursor solution is started. It can be avoided that sometimes the first resin solution or the first resin precursor solution hangs down and is mixed with the second resin solution or the second resin precursor solution.

  Here, an embodiment of the present invention will be described. In FIG. 3, sectional drawing of the multilayer polyimide tubular body which concerns on one Embodiment of this invention is shown. The multilayer polyimide tubular product 30 is a multilayer polyimide tubular product having a two-layer structure, and is mainly composed of a first polyimide resin layer 33 and a second polyimide resin layer 31. In this multilayer polyimide tubular product 30, a polyimide resin that forms the first polyimide resin layer 33 and a polyimide that forms the second polyimide resin layer 31 between the first polyimide resin layer 33 and the second polyimide resin layer 31. There is a polyimide resin mixed layer 32 in a state where the resin is mixed (a state where the two liquids are in contact with each other and are compatible). In the present embodiment, three or more polyimide resin layers may be formed on the multilayer polyimide tubular product.

  When the polyimide precursor solution is used as a raw material, the multilayer polyimide tubular product 30 according to the embodiment of the present invention can maintain the characteristics of each raw material by a free combination thereof.

  In the multilayer polyimide tubular product 30 according to the embodiment of the present invention, it is preferable that at least one of the first polyimide resin layer 33 and the second polyimide resin layer 31 includes fine particles. This is because new characteristics can be added to the multilayer polyimide tubular product 30 by adding fine particles. The fine particles are preferably at least one fine particle selected from the group consisting of conductive fine particles, thermally conductive fine particles, and fluororesin fine particles.

  For example, when the multilayer polyimide tubular product 30 is used as an intermediate transfer belt or the like, it is preferable to add conductive fine particles to one of the polyimide resin layers 31 and 33. This is because the addition of the conductive fine particles can adjust precise electrical characteristics such as the surface resistivity and volume resistivity of the semiconductive region. In addition, by changing the type and mixing amount of the conductive fine particles in each polyimide resin layer 31 and 33 of the multilayer polyimide tubular body 30, the electrical characteristics and mechanical characteristics or surface characteristics necessary for the multilayer polyimide tubular body 30 are combined. This is because it can be given. As the conductive fine particles, fine particles such as carbon black, carbon nanofibers, graphite, metal powder, and nickel fibers can be used.

  For example, when the multilayer polyimide tubular product 30 is used as a fixing belt or the like, it is preferable to add heat conductive fine particles such as boron nitride to any one of the polyimide resin layers 31 and 33. In the film fixing device (see FIG. 2), in order to thermally fix the toner image formed on the copy paper at high speed, it is necessary to efficiently transmit the heat generated by the ceramic heater to the toner fixing. This is because a higher thermal conductivity is preferable. And, for example, by combining and laminating a polyimide resin layer in which a large amount of heat conductive fine particles are mixed with a polyimide resin layer in which a small amount of heat conductive fine particles are mixed or in which no fine particles are mixed, high thermal conductivity and mechanical It is possible to realize a fixing belt that has both characteristics and characteristics. In the multilayer polyimide tubular product 30 according to the present embodiment, it is preferable that the former is the first polyimide resin layer 33 and the latter is the second polyimide resin layer 31. Insulating inorganic fine particles are preferable as such heat conductive fine particles, for example, boron nitride, alumina, silicon carbide, potassium titanate, aluminum nitride, mica, silica, titanium oxide, talc, calcium carbonate, and A mixture of two or more of these may be mentioned. Among these, boron nitride, alumina, silicon carbide, and aluminum nitride are more preferable heat conductive fine particles.

  In addition, content of heat conductive microparticles | fine-particles is 10 to 60 weight% normally, Preferably it is 20 to 50 weight%. In the case of a single-layer polyimide tubular material, if the content of the heat conductive fine particles exceeds 30%, the mechanical properties deteriorate, or the surface of the tubular material becomes rough and cannot be used as a fixing belt. The multilayer polyimide tubular product 30 according to the invention includes a polyimide resin layer containing a small amount of thermally conductive fine particles (containing 0 to 10% by weight) on at least one of an outer surface and an inner surface of a polyimide layer containing conductive fine particles. By forming, thermal conductivity can be improved without deteriorating mechanical properties. In addition, the average particle diameter of heat conductive fine particles is the range of 1-20 micrometers, Preferably it is 5-15 micrometers.

  Moreover, in the multilayer polyimide tubular product 30 according to the embodiment of the present invention, it is preferable that any polyimide resin layer contains fluororesin fine particles. When the polyimide precursor solution is mixed with the polyimide precursor solution in advance and then the polyimide precursor solution is molded, and the polyimide precursor is imidized at a temperature equal to or higher than the melting point of the fluororesin, it is applied to one or both surfaces of the polyimide resin layer. This is because a fluororesin layer having protrusions is formed, and a multilayer polyimide tubular product excellent in releasability and low friction can be obtained. When the fluorine resin fine particles are contained in the polyimide resin layer, the mechanical properties of the polyimide resin layer are reduced in proportion to the mixing amount as in the case where the heat conductive fine particles are mixed. However, as an example, only the polyimide precursor solution is first molded on the core, and the polyimide precursor solution mixed with fluororesin fine particles is molded on the outer surface, and then imidized at a temperature equal to or higher than the melting point of the fluororesin. When completed, a fluororesin layer having protrusions is formed, and a multilayer polyimide tubular product having excellent releasability and high mechanical properties can be produced.

  The fluororesin fine particles to be mixed with the polyimide precursor solution are not particularly limited, and polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene ( PCTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer (ETFE). In addition, these mixtures may be used as fluororesin fine particles. The mixing amount of the fluororesin fine particles is preferably set to 3 to 50% by weight with respect to the solid content of the polyimide precursor solution. Particularly preferably, it is 10 to 40% by weight. The average particle size of the fluororesin fine particles is preferably in the range of 0.1 to 25 μm. A more preferable average particle diameter is in the range of 1.0 to 15 μm.

  Moreover, in the multilayer polyimide tubular product according to the embodiment of the present invention, each polyimide resin layer can be produced from different raw materials. The polyimide resin layer of the multilayer polyimide tubular product according to the embodiment of the present invention is obtained using aromatic tetracarboxylic acid anhydride and aromatic diamine as raw materials. For example, a polyimide resin composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and paraphenylenediamine (PPD) is rigid and has excellent mechanical properties, but has a small tensile elongation, Moreover, the price of each monomer is high. On the other hand, a polyimide resin composed of pyromellitic dianhydride (PMDA) and 4,4'-diaminodiphenyl ether (ODA) has a large tensile elongation and flexible properties, and the price of each monomer is low. Therefore, by multilayering these two kinds of polyimide resins, it is possible to obtain a multilayer polyimide tubular product having characteristics required for a fixing belt, an intermediate transfer belt, and a photosensitive drum while keeping the manufacturing cost low.

  In addition, 4,4′-diaminodiphenylsulfone (44DDS), 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl and the like, and 2,2-bis [4- (dicarboxyphenoxy) phenyl Propane dianhydride (BPADA), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanoic acid dianhydride or 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) ) And the like have high light transmission properties, but have the disadvantages of low mechanical properties and low glass transition temperature. By multilayering these transparent polyimides and the above-mentioned rigid polyimide made of BPDA and PPD, a multilayer polyimide tubular product having high light transmittance, mechanical properties, and heat resistance can be obtained.

  Moreover, since the multilayer polyimide tubular product 30 according to the embodiment of the present invention can freely select the film thickness of each layer by changing the size of the film forming die, the characteristics of each polyimide resin layer are strong and weak. You can turn on. The thickness of each polyimide resin layer is preferably in the range of 3 μm to 500 μm, more preferably in the range of 5 μm to 300 μm.

  The inner diameter of the multilayer polyimide tubular product according to the embodiment of the present invention is not particularly limited, but is preferably in the range of 0.1 mm to 1000 mm. The multilayer polyimide tubular material used as a member of an electrophotographic image forming apparatus preferably has an inner diameter in the range of 10 mm to 500 mm, and the multilayer polyimide tubular material used as a medical catheter or the like has an inner diameter in the range of 0.5 mm to 10 mm. It is preferable to be within.

  Next, in the multilayer polyimide tubular product according to the embodiment of the present invention, a polyimide precursor obtained by polymerizing an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic polar solvent is used as a polyimide resin layer. It is preferable that it is imidized. By using the polyimide precursor solution, not only can the fine particles be uniformly dispersed, but the thickness of each polyimide resin layer can be set broadly by adjusting the viscosity and solid content concentration, and can be liquid molded at room temperature and relatively compact. This is because it can be molded by equipment.

  The polyimide precursor solution can be obtained by reacting approximately equimolar amounts of aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent. Representative examples of aromatic tetracarboxylic dianhydrides include 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, 2,3,3', 4-biphenyltetra Carboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetra Carboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) propane dianhydride, perylene-3,4,9, Examples thereof include 10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, and bis (3,4-dicarboxyphenyl) sulfone dianhydride.

  Representative examples of aromatic diamines include 4,4'-diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 1,5-diaminonaphthalene, 3,3'-dichlorobenzidine, 3,3'-diamino. Diphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-biphenyldiamine, 4,4'-diaminodiphenyl sulfide-3,3'-diaminodiphenylsulfone, benzidine, 3,3'- Examples thereof include dimethylbenzidine, 4,4′-diaminophenylsulfone, 4,4′-diaminodiphenylpropane, m-xylylenediamine, hexamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine and the like.

  These aromatic tetracarboxylic dianhydrides and aromatic diamines can be used alone or in combination. Moreover, it can also complete and complete the polyimide precursor solution, and can also use those polyimide precursor solutions.

  Organic polar solvents for dissolving aromatic tetracarboxylic dianhydride and aromatic diamine include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide N, N-diethylacetamide, dimethyl sulfoxide, hexamethyl phosphortriamide, pyridine, dimethyltetramethylene sulfone, tetramethylene sulfone, propylene carbonate, γ-butyrolactone, and the like. In addition, these solvents may be used independently and may be used in mixture.

  The polyimide precursor solution is obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic polar solvent, usually at 90 ° C. or lower, and the solid content concentration in the solvent is produced. Although it is set according to the specifications and processing conditions of the multilayer polyimide tubular product, it is usually in the range of 10 to 50% by weight.

  In addition, when aromatic tetracarboxylic dianhydride and aromatic diamine are reacted in an organic polar solvent, the viscosity of the solution increases depending on the polymerization status. can do. Usually, it is used at a viscosity of 1 to 5000 poise, although it varies depending on manufacturing conditions and working conditions. In the embodiment of the present invention, since the polyimide precursor solution is laminated and molded, the viscosity of the polyimide precursor solution is preferably in the range of 500 to 2000 poise, more preferably 800 to 1500 poise. Moreover, it is preferable that the viscosity of each polyimide precursor solution at the time of shape | molding by laminating | stacking a polyimide precursor solution is a substantially the same viscosity, and the one where the viscosity of the polyimide precursor solution shape | molded in a lower layer is higher is more preferable.

  Next, in the embodiment according to the present invention, it is preferable that at least one of the inner surface and the outer surface of the multilayer polyimide tubular article is covered with a release layer. When a multilayer polyimide tubular material is used as a fixing belt or an intermediate transfer belt, it is easy to remove unfixed toner, and particularly when used as a fixing belt, adhesion (offset) of molten toner to the belt surface can be prevented. It is. The release layer is most preferably made of a fluororesin such as PTFE, PFA, FEP. These fluororesins may be used alone or in combination.

  And the multilayer polyimide tubular material which concerns on embodiment of this invention is mainly manufactured through a polyimide precursor solution recoating process and an imidation process. In the polyimide precursor solution overcoating step, the first polyimide precursor solution and the second polyimide precursor solution are applied in an overlapping manner on the outer surface of the columnar or cylindrical core. In the imidization step, the solvent is removed from the first polyimide precursor solution and the second polyimide precursor solution, and the first polyimide precursor and the second polyimide precursor are imidized. At this time, imidization may be realized by heating or may be realized by chemical treatment. In such a manufacturing method, since the polyimide precursor solution is applied to the core body only once, the thermal efficiency can be increased and the processing time can be shortened. Also, in the imidization step, the first polyimide precursor can be reduced. Since the first polyimide precursor and the second polyimide precursor are integrated, a high-quality multilayer polyimide tubular product is produced.

  And in order to implement such a manufacturing method, it is preferable to use the film forming apparatus as shown in FIG.

  As shown in FIG. 4, the film forming apparatus 50 mainly includes a first film forming die 54, a second film forming die 55, a first pressure tank 58, a second pressure tank 59, and a first solution valve. 60, second solution valve 61, first main pipe, second main pipe, first distribution pipe 62, second distribution pipe 63, first distributor 64, second distributor 65, first pressurization valve 68, and second A pressurizing valve 69 is used.

  The first film forming die 54 is a hollow cylindrical formed body. Further, the second film forming die 55 is a hollow cylindrical formed body like the first film forming die 54. The inner diameters of the film forming dies 54 and 55 are determined by the specifications of the inner diameter and thickness of the target multilayer polyimide tubular product. At this time, it is necessary to consider the outer diameter of the core, the pulling speed of the core, the viscosity of the polyimide precursor solution, the discharge speed from the slit openings 66 and 67, and the like. Further, the inner peripheral diameter of the second film forming die 55 is slightly smaller than the inner peripheral diameter of the first film forming die 54. The first film forming die 54 is disposed close to the lower side of the second film forming die 55 so that the axis thereof is along the axis of the second film forming die 55. In the first film forming die 54 and the second film forming die 55, a plurality of slit openings 66 and 67 are formed on the inner peripheral wall over the entire circumference with a predetermined gap. This is because when the slit openings 66 and 67 are formed in this way, there is no uneven ejection in the circumferential direction, and a solution molding layer having a uniform thickness can be formed. Moreover, it is preferable that the width | variety of a slit opening exists in the range of 0.5 mm-5 mm. The first film forming die 54 and the second film forming die 55 are formed with a plurality of liquid inlets on the outer peripheral wall, and a plurality of distribution pipes 62 and 63 are connected to the liquid inlets. When three or more film forming dies are stacked, it is necessary that the inner diameter of the film forming die located in the lower stage is small and the inner diameter of the film forming die located in the upper stage is increased.

  The first pressurized tank 58 and the second pressurized tank 59 are storage containers for storing the polyimide precursor solutions 56 and 57. In these pressurized tanks 58 and 59, pressurizing valves 68 and 69 are attached to the upper lids, respectively, and solution valves 60 and 61 are attached to the lower sides thereof.

  A pressurized air cylinder or the like is attached to the first pressure valve 68 and the second pressure valve 69, and when the first pressure valve 68 and the second pressure valve 69 are opened, the inside of the pressure tanks 58 and 59 Pressurize. At this time, when the solution valves 60 and 61 are in the open state, the polyimide precursor solution stored in the pressurized tanks 58 and 59 is delivered to the hollow space of the film forming dies 54 and 55.

  The first solution valve 60 and the second solution valve 61 are open / close type electric valves. Note that these solution valves 60 and 61 are connected to a timing control device (not shown) in communication. When the operation start button of the timing control device is pressed, first, the first solution valve 60 is opened, and then for a predetermined time. After the elapse of time, the second solution valve 61 is opened.

  The first distributor 62 and the second distributor 63 have one inlet and a plurality of outlets, a main pipe is connected to the inlets, and distribution pipes 62 and 63 are connected to the outlets. That is, the distributors 62 and 63 play a role of distributing the polyimide precursor solution delivered from the pressurized tanks 68 and 69 through the main pipe to the plurality of paths.

  That is, when the operation start button of the timing control device is pushed with the first pressurization valve 68 and the second pressurization valve 69 open, the first polyimide precursor solution 56 is passed through the plurality of paths by the first distributor 64. Are distributed to the first film forming die 54 and discharged from the slit opening 66. Then, after a little delay, the second polyimide precursor solution 57 is distributed to the plurality of paths by the second distributor 65, and then supplied to the second film forming die 55 and discharged from the slit opening 67.

  Next, the process of solution molding will be described. A hanging string 70 is passed inside the film forming dies 54 and 55 of the film forming apparatus 50, and the hanging string is fixed to the upper end portion of the core body 51. Then, the hanging strap 70 is tied to a drive motor (not shown) so that the core body 51 can be pulled up at a predetermined speed. And the 1st pressurization valve 68 and the 2nd pressurization valve 69 are opened, pressurized air is sent to each pressurization tank 58, 59, and the operation start button of a timing control device is pushed. Then, first, the first solution valve 60 is opened, and the first polyimide precursor solution 56 is discharged from the slit opening 66 of the first film forming die 54. At the same time, when the core body 51 is pulled up at a predetermined speed, the first polyimide precursor solution film 52 is formed on the outer surface of the core body 51. At this time, by controlling at least one of the discharge amount of the first polyimide precursor solution 56 and the pulling speed of the core 51, the first polyimide precursor solution 56 can be formed into a solution with a constant thickness. After a while after the first solution valve 60 is opened, the second solution valve 61 is opened, and the second polyimide precursor solution 57 is discharged from the slit opening 67 of the second film forming die 55. The Then, a second polyimide precursor solution film 53 is formed on the first polyimide precursor solution film 52. That is, in this film forming apparatus 50, the first polyimide resin layer 33 (inner layer) of the multilayer polyimide tubular product 30 is formed by the first polyimide precursor solution 56, and the multilayer polyimide tubular product 30 of the second polyimide precursor solution 57 is formed. The second polyimide resin layer 31 (outer layer) is formed. At this time, by controlling at least one of the discharge amount of the second polyimide precursor solution 57 and the pulling speed of the core 51, the second polyimide precursor solution 57 can be formed into a solution with a constant thickness. In the preferred embodiment, a predetermined amount of the polyimide precursor solution is discharged from the slit openings 66 and 67 and the pulling speed of the core 51 is sequentially controlled. If it does in this way, the thickness of a polyimide precursor solution film can be made constant accurately.

  In such a solution molding, a self-aligning stress is applied to the core 51 by the viscosity and discharge force of the polyimide precursor solution discharged from the slit opening, so that the polyimide precursor solution film has a uniform thickness. Can be molded.

  The core 51 used in the embodiment of the present invention is not particularly limited as long as it has heat resistance that can withstand the heating for imidization. Metal is a preferable material judging from the workability and the dimensional accuracy of the core. Moreover, it is preferable that the outer surface of the core is covered with a release agent. Examples of the release agent include ceramic coating, fluororesin coating, and silicone coating.

  After this, the polyimide precursor solution coatings 52 and 53 are processed to a state where at least the strength as a tubular product can be maintained to produce a semi-cured polyimide tubular product, and a conductive primer is formed on the outer surface of the semi-cured polyimide tubular product. May be applied, dried, and then coated with a fluororesin, followed by heat treatment to simultaneously complete the imidization reaction and calcination of the fluororesin. When the multilayer polyimide tubular product 30 is used as a fixing belt or the like, it is essential to coat a release material such as a fluororesin in order to prevent the melted toner from being offset during heat fixing. Therefore, the firing temperature of the fluororesin must also exceed 330 degrees C. That is, by imidating the polyimide precursor and baking the fluororesin in the same process, the fixing belt can be manufactured at a low cost by simplifying the process and increasing the efficiency of electric energy. In the embodiment of the present invention, the “semi-cured polyimide” is a polyimide at a stage where imidization is not completed, and the polyimide precursor molding layer has a thickness shrinkage of 50 to 95%. Say. The thickness reduction rate can be obtained by the following equation (1).

以下、実施例を用いて本発明を具体的に説明するが、本発明はこれらの実施例に限定されるものではない。

EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to these Examples.

(Fixing belt production)
Boron nitride (Mitsui Chemicals, Inc. MBN-010T), which is a thermally conductive fine particle, is added to the Pyre-ML RC5063 polyamic acid solution manufactured by IST Co., Ltd. at 38% by weight based on the solid content of the polyamic acid solution. After mixing, the viscosity was adjusted to 1000 poise to prepare a first polyimide precursor solution 56. The solid content of Pyre-ML RC5063 was 17.5% by weight. Next, a second polyimide precursor solution 57 was prepared by adjusting the viscosity to 1000 poise without mixing any fine particles in the Pyr-ML RC5063 polyamic acid solution manufactured by IST.

  Moreover, what coated the surface of the aluminum cylindrical core body of outer diameter 24mm length 500mm as the core body 51 with the silicon oxide film was prepared. The average surface roughness Rz of the core body 51 was 1.2 μm as measured by JIS-B0601.

  Further, the above-described film forming apparatus 50 was used as the film forming apparatus. In the present embodiment, the inner diameter of the first film forming die 54 is 25.4 mm, and the inner diameter of the second film forming die 55 is 25.6 mm. The size of the slit openings 66 and 67 formed on the inner peripheral walls of the respective film forming apparatuses 54 and 55 is 3.0 ± 0.05 mm. In addition, six distribution pipes 62 and 63 are connected to the distributors 64 and 65.

  Hereinafter, the production of the fixing belt according to the present embodiment will be described in detail.

  The first polyimide precursor solution 56 was charged into the first pressure tank 58 of the film forming apparatus 50, and the second polyimide precursor solution 57 was charged into the second pressure tank 59. First, the core 51 is suspended by the hanging strap 70 so that the axis of the core 51 is oriented in the vertical direction and inserted into the inner hole of the first film forming die 54, and then the uppermost end of the core 51 is The core body 51 was disposed so as to be substantially at the same position as the slit opening 66 of the one-film molding die 54. Next, the first solution valve 60 is opened while applying a pressure of 0.05 MPa from the first pressure valve 68 into the first pressure tank 58, and the first polyimide precursor solution 56 is pumped to the first film forming die 54. did. In the present embodiment, when the first polyimide precursor solution 56 is sent to the first distributor 64, it is then distributed to the six first distribution pipes 62, and a predetermined portion of the first film forming die 54. To the inner space of the first film forming die 54. At the same time, the core 51 is pulled up in the Y direction at a speed of 600 mm / min, and when the position 30 mm below the uppermost end of the core 51 passes through the first slit opening 66, the first slit opening 66 passes through the first slit opening 66. The polyimide precursor solution 56 was discharged at 20 g / min, and solution molding of the first polyimide precursor solution 56 was started on the outer surface of the core body 51 with a thickness of about 500 μm.

  On the other hand, the second polyimide precursor solution 57 stored in the second pressure tank 59 is also supplied from the second pressure valve 69 to 0.05 MPa in the second pressure tank 59 in the same manner as the first polyimide precursor solution 56. The second solution valve 61 was opened while the pressure was applied, and the pressure was fed to the second film forming die 55. In the present embodiment, the second polyimide precursor solution 57 is also distributed to the six second distribution pipes 63 after being sent to the second distributor 65 in the same manner as the first polyimide precursor solution 56. The second film forming die 55 is delivered from a predetermined location to the inner space of the second film forming die 55. Immediately after the molding start position of the first polyimide precursor solution 56 molded on the surface of the core 51 passes through the second slit opening 67, the second polyimide precursor solution 57 is removed from the second slit opening 67 by 4 g / The second polyimide precursor solution 57 was molded on the molding layer of the first polyimide precursor solution 56 at a thickness of about 100 μm.

  The first polyimide precursor solution 56 and the second polyimide precursor solution 57 are laminated on the surface of the core body 51 in two layers, and the solution molding is continued, and the position about 30 mm above the lowest end of the core body 51 is the second slit. When passing through the position of the opening 67, the pressure feeding of the polyimide precursor solutions 56, 57 from both the pressure tanks 58, 59 is stopped, and a solution molding layer formed by lamination on the core body 51 to a length of about 440 mm is obtained. It was. Thereafter, the core body 51 is removed from the film forming apparatus 50, and the core body 51 is placed in an oven as it is, dried at 120 ° C. for 60 minutes, heated to 200 ° C. over 40 minutes, and kept at the same temperature for 20 minutes. Thus, a semi-cured polyimide tubular product at an intermediate stage of imidization was obtained. The semi-cured polyimide tubular product had a thickness shrinkage of 88%.

  Next, the semi-cured polyimide tubular material is dipped in a fluororesin conductive primer solution (DuPont: Teflon 855-003) and pulled up, and the fluoropolymer conductive primer solution is applied to the outer surface of the semi-cured polyimide tube. After coating to a thickness of 4 μm, the semi-cured polyimide tubular product was dried at a temperature of 200 ° C. for 30 minutes and then cooled to room temperature again to obtain a primer-coated semi-cured polyimide tubular product.

  In addition, a fluorinated resin dispersion (manufactured by DuPont: registered trademark Teflon 855-510) (solid content concentration 45% by weight) in which PTFE resin and PFA resin are mixed at a weight ratio of 7: 3 is used. Titanium oxide aqueous dispersion EP677 made by 20% by weight and 2% by weight Ketchin Black aqueous dispersion made by Lion Corporation, which is a kind of carbon black, were added to prepare a mixed dispersion. Then, the primer-coated semi-cured polyimide tubular material is dipped in the mixed dispersion and pulled up. After coating the mixed dispersion to a thickness of 20 μm on the outer surface of the primer-coated semi-cured polyimide tube, the primer-coated semi-cured polyimide tubular material is removed. Heat at 200 ° C. for 10 minutes, at 320 ° C. for 40 minutes, and at 400 ° C. for 20 minutes (at this time, imidization of the polyimide precursor and baking of the fluororesin are performed simultaneously), and then the outer periphery of the core The desired multi-layer polyimide tubular product (fixing belt) was manufactured by separating the tubular product formed in the above structure from the core. By the way, this multilayer polyimide tubular product has a primer layer and a fluororesin release layer on the outer surface of a multilayer polyimide tubular product having a two-layer structure comprising a polyimide inner layer of about 50 μm thickness containing boron nitride and an polyimide outer layer of about 8 μm thickness. Can be used as a fixing belt. The inner diameter of the multilayer polyimide tubular product is 24 mm, the total thickness of the multilayer polyimide tubular product including the fluororesin layer is about 80 μm, and the average surface roughness (Rz) of the multilayer polyimide tubular product. Was 1.25 μm.

As a result of observing a boundary portion between the first polyimide layer formed from the first polyimide precursor solution 56 and the second polyimide layer formed from the second polyimide precursor solution 57 with a microscope, the two polyimides were mixed with each other. A layer having such a pattern was confirmed. Moreover, these two layers were integrated in a state where they were firmly bonded and could not be peeled off. The multilayer polyimide tubular product had a tensile strength of 32 kgf / mm ² and had sufficient mechanical properties for use as a fixing belt.

  This multilayer polyimide tube (fixing belt) is incorporated in the fixing device 26 of the printer shown in FIG. 2, and a paper passing durability test is performed at a copying speed of 24 sheets per minute. As a result, a clear image is obtained with good thermal conductivity. I was able to. Further, due to the mechanical properties of the single polyimide layer formed from the second polyimide precursor solution 57, a clear image could be obtained without any problem even when fixing 200,000 sheets.

(Preparation of intermediate transfer belt)
Carbon black (Mitsubishi Chemical Co., Ltd., trade name MA78) is mixed with PIST-ML RC5063 polyamic acid solution manufactured by IST, so that the solid content of the polyamic acid solution is 16.5% by weight. After that, the first polyimide precursor solution 56 was prepared by adjusting the viscosity to 1200 poise. The solid content of Pyre-ML RC5063 was 17.5% by weight. Next, carbon black (MA78) is mixed with Pyre-ML RC5063 polyamic acid solution manufactured by IST Co., Ltd. so as to be 15% by weight with respect to the solid content of the polyamic acid solution, and the viscosity is adjusted to 1200 poise. Thus, a second polyimide precursor solution 57 was prepared.

  Further, as the core body 51, an aluminum cylindrical core body having an outer diameter of 229 mm and a length of 500 mm coated with a silicon oxide film was prepared. The average surface roughness Rz of the core body 51 was 1.8 μm as measured by JIS-B0601.

  Further, the above-described film forming apparatus 50 was used as the film forming apparatus. In the present embodiment, the inner diameter of the first film forming die 54 is 231 mm, and the inner diameter of the second film forming die 55 is 231.4 mm. The size of the slit openings 66 and 67 formed on the inner peripheral walls of the respective film forming apparatuses 54 and 55 is 3.5 ± 0.05 mm. Further, twelve distribution pipes 62 and 63 are connected to the distributors 64 and 65.

  Hereinafter, the production of the intermediate transfer belt according to the present embodiment will be described in detail.

  The first polyimide precursor solution 56 was charged into the first pressure tank 58 of the film forming apparatus 50, and the second polyimide precursor solution 57 was charged into the second pressure tank 59. First, the core 51 is suspended by the hanging strap 70 so that the axis of the core 51 is oriented in the vertical direction and inserted into the inner hole of the first film forming die 54, and then the uppermost end of the core 51 is The core body 51 was disposed so as to be substantially at the same position as the slit opening 66 of the one-film molding die 54. Next, the first solution valve 60 is opened while applying a pressure of 0.05 MPa from the first pressure valve 68 into the first pressure tank 58, and the first polyimide precursor solution 56 is pumped to the first film forming die 54. did. In the present embodiment, when the first polyimide precursor solution 56 is sent to the first distributor 64, it is then distributed to the 12 first distribution pipes 62, and a predetermined portion of the first film forming die 54. To the inner space of the first film forming die 54. At the same time, the core body 51 is pulled up in the Y direction at a speed of 600 mm / min, and when the position 50 mm below the uppermost end of the core body 51 passes through the first slit opening 66, the first slit opening 66 passes through the first slit opening 66. The polyimide precursor solution 56 was discharged at 20 g / min, and solution molding of the first polyimide precursor solution 56 was started on the outer surface of the core body 51 with a thickness of about 500 μm.

  On the other hand, the second polyimide precursor solution 57 stored in the second pressure tank 59 is also supplied from the second pressure valve 69 to 0.05 MPa in the second pressure tank 59 in the same manner as the first polyimide precursor solution 56. The second solution valve 61 was opened while the pressure was applied, and the pressure was fed to the second film forming die 55. In the present embodiment, the second polyimide precursor solution 57 is also distributed to the 12 second distribution pipes 63 after being sent to the second distributor 65 in the same manner as the first polyimide precursor solution 56. The second film forming die 55 is delivered from a predetermined location to the inner space of the second film forming die 55. Then, immediately after the molding start position of the first polyimide precursor solution 56 molded on the surface of the core 51 passes through the second slit opening 67, the second polyimide precursor solution 57 is removed from the second slit opening 67 by about 8 g. The second polyimide precursor solution 57 was formed on the molding layer of the first polyimide precursor solution 56 with a thickness of about 200 μm.

  The first polyimide precursor solution 56 and the second polyimide precursor solution 57 are laminated on the surface of the core body 51 in two layers, and the solution molding is continued, and the position about 50 mm above the lowest end of the core body 51 is the second slit. When passing through the position of the opening 67, the pressure feeding of the polyimide precursor solutions 56, 57 from both the pressure tanks 58, 59 is stopped, and a solution molding layer is formed that is laminated on the core body 51 to a length of about 400 mm. It was. Thereafter, the core body 51 is removed from the film forming apparatus 50, and the core body 51 is placed in an oven as it is, dried at 120 ° C. for 40 minutes, heated to 200 ° C. over 40 minutes, and kept at the same temperature for 20 minutes. After that, the temperature was raised to 320 ° C. in 20 minutes and held for 30 minutes, the temperature was raised to 350 ° C. in 15 minutes and heated at the same temperature for 20 minutes to complete imidization, and then the core 51 was removed from the oven and cooled. Thereafter, the multilayer polyimide tubular material was removed from the core body 51. The multilayer polyimide tubular product had a thickness of 70 ± 3 μm, and the multilayer polyimide tubular product had an inner diameter of 229 mm. Then, this multilayer polyimide tubular product was cut into a length of 380 mm to obtain a multilayer polyimide tubular product for A3 size.

The surface resistivity of the outer surface of this multilayer polyimide tubular product when applied with 50V voltage is 1 × 10 ⁸ to 1 × 10 ⁹ Ω / □, and the volume resistivity is 3 × 10 ⁸ to 1 × 10 ⁹ Ω / cm. Thus, a multilayer polyimide tubular product having electrical characteristics with small variations was obtained. Further, the uniformity of the thickness and the circumference were also good. This multilayer polyimide tubular article is also excellent in mechanical properties. As a result of being incorporated in the tandem laser beam printer of FIG. 1 and used as an intermediate transfer belt, a clear color image is produced without causing color misregistration or color unevenness. Could get. Further, even when printing was continuously performed, no image defect was observed.

(Production of transparent multilayer polyimide tubular material for photosensitive drum)
A first polyimide precursor solution 56 was prepared by adjusting the viscosity to 1000 poise without mixing any fine particles in the Pyr-ML RC5063 polyamic acid solution manufactured by IST. The solid content of Pyre-ML RC5063 was 17.5% by weight. Next, the second polyimide precursor solution 57 was synthesized under the following conditions.

  A 3000 mL three-necked separable flask was equipped with a stirring rod equipped with stirring blades and a nitrogen gas inlet tube to prepare a reaction vessel. All the reactions were performed under a nitrogen atmosphere. First, 4, 4′-diaminodiphenyl sulfone (44DDS) (trade name “Seika Cure S” manufactured by Wakayama Seika Kogyo Co., Ltd.) is used as the diamine component so that the concentration of the polyimide precursor solution is 33% by weight. ) 203.86 g (0.822 mol) and 1,005 g of N, N-dimethylacetamide (DMAC) (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a reaction solvent were charged into a reaction vessel. Next, after 44DDS is completely dissolved in DMAC, 2,2-bis [4- (dicarboxyphenoxy) phenyl] propane dianhydride (BPADA) (Shanghai Synthetic Resin Research Institute) is used as the tetracarboxylic dianhydride component. Product name “BPADA”) 107.93 g (0.208 mol) and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) (trade name “BPDA”, manufactured by Mitsubishi Chemical Corporation) ”) 183.07 g (0.623 mol) was added in the form of a solid, reacted at 40 ° C. for 12 hours, and a viscous transparent polyimide precursor solution having a viscosity of 900 poise (hereinafter referred to as precursor of this transparent polyimide). The body solution was referred to as a second polyimide precursor solution 57).

  Also prepared as a core 51 is an aluminum cylindrical core having an outer diameter of 30 mm and a length of 500 mm, which has been polished so that the average surface roughness (Rz) of the outer surface is 1 μm or less, and is coated with a silicon oxide film. did. The formation of the silicon oxide film can be realized by immersing the polished aluminum cylindrical core in a silicon oxide coating agent and then heating it at 370 ° C. for 30 minutes.

  Further, the above-described film forming apparatus 50 was used as the film forming apparatus. In the present embodiment, the inner diameter of the first film forming die 54 is 31.1 mm, and the inner diameter of the second film forming die 55 is 32.3 mm. The size of the slit openings 66 and 67 formed on the inner peripheral walls of the respective film forming apparatuses 54 and 55 is 3.0 ± 0.05 mm. In addition, six distribution pipes 62 and 63 are connected to the distributors 64 and 65.

  Hereinafter, the production of the fixing belt according to the present embodiment will be described in detail.

  The first polyimide precursor solution 56 was charged into the first pressure tank 58 of the film forming apparatus 50, and the second polyimide precursor solution 57 was charged into the second pressure tank 59. First, the core 51 is suspended by the hanging strap 70 so that the axis of the core 51 is oriented in the vertical direction and inserted into the inner hole of the first film forming die 54, and then the uppermost end of the core 51 is The core body 51 was disposed so as to be substantially at the same position as the slit opening 66 of the one-film molding die 54. Next, the first solution valve 60 is opened while applying a pressure of 0.05 MPa from the first pressure valve 68 into the first pressure tank 58, and the first polyimide precursor solution 56 is pumped to the first film forming die 54. did. In the present embodiment, when the first polyimide precursor solution 56 is sent to the first distributor 64, it is then distributed to the six first distribution pipes 62, and a predetermined portion of the first film forming die 54. To the inner space of the first film forming die 54. At the same time, the core 51 is pulled up in the Y direction at a speed of 600 mm / min, and when the position 30 mm below the uppermost end of the core 51 passes through the first slit opening 66, the first slit opening 66 passes through the first slit opening 66. The polyimide precursor solution 56 was discharged at 14 g / min, and solution molding of the first polyimide precursor solution 56 was started on the outer surface of the core body 51 with a thickness of about 350 μm.

  On the other hand, the second polyimide precursor solution 57 stored in the second pressure tank 59 is also supplied from the second pressure valve 69 to 0.05 MPa in the second pressure tank 59 in the same manner as the first polyimide precursor solution 56. The second solution valve 61 was opened while the pressure was applied, and the pressure was fed to the second film forming die 55. In the present embodiment, the second polyimide precursor solution 57 is also distributed to the six second distribution pipes 63 after being sent to the second distributor 65 in the same manner as the first polyimide precursor solution 56. The second film forming die 55 is delivered from a predetermined location to the inner space of the second film forming die 55. Then, immediately after the molding start position of the first polyimide precursor solution 56 molded on the surface of the core 51 passes through the second slit opening 67, the second polyimide precursor solution 57 is removed from the second slit opening 67 by 24 g / The second polyimide precursor solution 57 was molded on the molding layer of the first polyimide precursor solution 56 at a thickness of about 600 μm.

  The first polyimide precursor solution 56 and the second polyimide precursor solution 57 are laminated on the surface of the core body 51 in two layers, and the solution molding is continued, and the position about 30 mm above the lowest end of the core body 51 is the second slit. When passing through the position of the opening 67, the pressure feeding of the polyimide precursor solutions 56, 57 from both the pressure tanks 58, 59 is stopped, and a solution molding layer formed by lamination on the core body 51 to a length of about 440 mm is obtained. It was. Thereafter, the core body 51 is removed from the film forming apparatus 50, and the core body 51 is placed in an oven as it is, dried at 120 ° C. for 40 minutes, heated to 200 ° C. over 40 minutes, and kept at the same temperature for 20 minutes. After that, the temperature was raised to 320 ° C. over 20 minutes and held for 30 minutes to complete imidization, and then the core 51 was taken out of the oven and cooled. Then, the multilayer polyimide tubular product was removed from the core 51, and the characteristics of the multilayer polyimide tubular product were measured.

The total thickness of the multilayer polyimide tubular product was 85 ± 3 μm, and the thickness of the first polyimide resin layer formed from the first polyimide precursor solution 56 was about 35 μm. Moreover, the tensile strength of this multilayer polyimide tubular product was 24.0 kgf / mm ² . Moreover, the light transmittances of the multilayer polyimide tubular products at wavelengths of 550 nm and 780 nm are 74.2% and 84.8%, respectively, and the light transmittance and mechanical characteristics required for applications such as back exposure. Was able to produce a transparent multilayer polyimide tubular product.

(Preparation of fluororesin mixed multilayer polyimide tube)
A first polyimide precursor solution 56 was prepared by adjusting the viscosity to 1000 poise without mixing any fine particles in the Pyr-ML RC5063 polyamic acid solution manufactured by IST. The solid content of Pyre-ML RC5063 was 17.5% by weight. Next, PTFE powder having an average particle size of 3.0 μm (melting point: 327 ° C., trade name Zonyl MP1100, manufactured by DuPont) was added to the Pyre-ML RC5063 polyamic acid solution manufactured by IST Co., Ltd. After adding PTFE powder in the above polyamic acid solution uniformly and filtering the coarse foreign matter using a 250 mesh stainless steel wire, the first polyimide is stirred. A precursor solution 56 was obtained.

  In addition, an aluminum cylindrical core body having an outer diameter of 24 mm and a length of 500 mm used in Example 1 was prepared as the core body 51.

  Further, the above-described film forming apparatus 50 was used as the film forming apparatus. In the present embodiment, the inner diameter of the first film forming die 54 is 24.8 mm, and the inner diameter of the second film forming die 55 is 25.6 mm. The size of the slit openings 66 and 67 formed on the inner peripheral walls of the respective film forming apparatuses 54 and 55 is 3.0 ± 0.05 mm. In addition, six distribution pipes 62 and 63 are connected to the distributors 64 and 65.

  Hereinafter, the production of the fluororesin mixed multilayer polyimide tubular product according to this example will be described in detail.

  The first polyimide precursor solution 56 was charged into the first pressure tank 58 of the film forming apparatus 50, and the second polyimide precursor solution 57 was charged into the second pressure tank 59. First, the core 51 is suspended by the hanging strap 70 so that the axis of the core 51 is oriented in the vertical direction and inserted into the inner hole of the first film forming die 54, and then the uppermost end of the core 51 is The core body 51 was disposed so as to be substantially at the same position as the slit opening 66 of the one-film molding die 54. Next, the first solution valve 60 is opened while applying a pressure of 0.05 MPa from the first pressure valve 68 into the first pressure tank 58, and the first polyimide precursor solution 56 is pumped to the first film forming die 54. did. In this embodiment, when the first polyimide precursor solution 56 is sent to the first distributor 64, it is then distributed to the six distribution pipes 62, and the first polyimide precursor solution 56 is supplied from a predetermined portion of the first film forming die 54. One film forming die 54 is delivered to the inner space. At the same time, the core 51 is pulled up in the Y direction at a speed of 600 mm / min, and when the position 30 mm below the uppermost end of the core 51 passes through the first slit opening 66, the first slit opening 66 passes through the first slit opening 66. The polyimide precursor solution 56 was discharged at 8 g / min, and solution molding of the first polyimide precursor solution 56 was started on the outer surface of the core body 51 with a thickness of about 200 μm.

  On the other hand, the second polyimide precursor solution 57 stored in the second pressure tank 59 is also supplied from the second pressure valve 69 to 0.05 MPa in the second pressure tank 59 in the same manner as the first polyimide precursor solution 56. The second solution valve 61 was opened while the pressure was applied, and the pressure was fed to the second film forming die 55. In the present embodiment, the second polyimide precursor solution 57 is also distributed to the six distribution pipes 63 after being sent to the second distributor 65, similarly to the first polyimide precursor solution 56. It is delivered from a predetermined location of the two-film forming die 55 to the inner space of the second film-forming die 55. Immediately after the molding start position of the first polyimide precursor solution 56 molded on the surface of the core 51 passes through the second slit opening 67, the second polyimide precursor solution 57 is removed from the second slit opening 67 by 16 g / The second polyimide precursor solution 57 was molded on the molding layer of the first polyimide precursor solution 56 at a thickness of about 400 μm.

  The first polyimide precursor solution 56 and the second polyimide precursor solution 57 are laminated on the surface of the core body 51 in two layers, and the solution molding is continued, and the position about 30 mm above the lowest end of the core body 51 is the second slit. When passing through the position of the opening 67, the pressure feeding of the polyimide precursor solutions 56, 57 from both the pressure tanks 58, 59 is stopped, and a solution molding layer formed by lamination on the core body 51 to a length of about 440 mm is obtained. It was. Thereafter, the core body 51 is removed from the film forming apparatus 50, and the core body 51 is placed in an oven as it is, dried at 120 ° C. for 60 minutes, heated to 200 ° C. over 40 minutes, and kept at the same temperature for 20 minutes. Then, the temperature was raised to a temperature of 400 ° C. in 20 minutes, and the mixture was heated at the same temperature for 15 minutes to complete imidization. Then, after the core body 51 was cooled to room temperature, the multilayer polyimide tubular material was removed from the core body 51.

The thickness of the obtained multilayer polyimide tubular product was 58 ± 3 μm, and the inner diameter of this multilayer polyimide tubular product was 24 mm. Moreover, since the PTFE resin is melted and deposited on the surface of the outer polyimide layer of the multilayer polyimide tubular product, the multilayer polyimide tubular product has a high slip property. Then, after cutting both ends of this multilayer polyimide tubular article into a length of 240 mm (A4 size), it was incorporated into the fixing device 26 shown in FIG. 2 and image fixing was performed under conditions of 10 sheets per minute. A good image was obtained. Further, the multilayer polyimide tubular article has a tensile strength of 27 kgf / mm ^2, indicating the intensity of about 1.4 times as compared with the tensile strength 20 kgf / mm ² monolayer polyimide tubular article obtained by mixing a fluorine resin .

  In Example 1, carbon black (trade name MA78 manufactured by Mitsubishi Chemical Corporation) is added to PISTE-ML RC5063 polyamic acid solution (manufactured by IST) at 16.5% by weight with respect to the solid content of the polyamic acid solution. After mixing as described above, a fixing belt was produced under the same conditions as in Example 1 except that the second polyimide precursor solution 57 was prepared by adjusting the viscosity to 1200 poise.

  A scanning electron microscope (SEM) photograph of this multilayer polyimide tubular article is shown in FIG. In this photograph, the outermost layer 102 (shown by adjusting the inclination of the sample), the first polyimide resin layer (containing boron nitride) 103, the polyimide mixed layer (portion between white broken lines) 101, and the second polyimide The resin layer 104 is confirmed. Note that it is considered that the first polyimide resin and the second polyimide resin are mixed at the molecular level in the vicinity of the boundary line 101a indicated by the white thick solid line.

Moreover, these two layers were integrated in a state where they were firmly bonded and could not be peeled off. The multilayer polyimide tubular product had a tensile strength of 32 kgf / mm ² and had sufficient mechanical properties for use as a fixing belt.

(Comparative Example 1)
A fixing belt was produced under the same conditions as in Example 1 except that a single-layer polyimide tubular product was produced using only the first polyimide precursor solution 56 and the first film forming die 54 in Example 1. This single-layer polyimide tubular article has a high thermal conductivity because of the large amount of boron nitride mixed, and can sufficiently cope with a copying speed of 24 sheets per minute. However, the average surface roughness Rz of the outer surface was 5.6 due to the amount of boron nitride mixed, and toner offset occurred despite the coating with the fluororesin. Further, this single-layer polyimide tubular material was broken from the end during the test, and was not very usable as a fixing belt. The single-layer polyimide tubular product had a tensile strength of 15.5 kgf / mm ² .

(Comparative Example 2)
The core 51 used in Example 3 is immersed in the first polyimide precursor solution 56 used in Example 3 to a length of 400 mm and pulled up, and the first polyimide precursor solution 56 is attached to the outer surface of the core 51. After that, a ring-shaped die having an inner diameter of 30.7 mm was inserted from above the core body 51 and dropped and run under its own weight to form a first polyimide precursor solution 56 on the outer surface of the core body 51. The core 51 was heated at 120 ° C. for 40 minutes and at 200 ° C. for 30 minutes to obtain a semi-cured polyimide tubular product.

  Next, in the second polyimide precursor solution 57 synthesized in Example 3, the semi-cured polyimide tubular material is inserted into the core body 51 and is dipped up to a length of 380 mm, and is pulled up to the outer surface of the semi-cured polyimide tubular material. After the second polyimide precursor solution 57 is attached, a ring-shaped die having an inner diameter of 31.8 mm is inserted from above the core body 51 and is allowed to drop and run by its own weight, so that the second polyimide precursor solution is applied to the outer surface of the semi-cured polyimide tube. 57 was solution molded. Then, the core body 51 is put in an oven as it is, dried at 120 ° C. for 40 minutes, subsequently heated to a temperature of 200 ° C. in 30 minutes, held at the same temperature for 20 minutes, and further to a temperature of 320 ° C. The temperature was raised in 20 minutes and heated at the same temperature for 30 minutes to complete imidization. Thereafter, the core body 51 was taken out of the oven and cooled. And the transparent multilayer polyimide tubular thing was removed from the core 51, and the physical property was measured.

The thickness of the first polyimide layer formed from the first polyimide precursor solution 56 was about 32 μm. The total thickness of the multilayer polyimide tubular product was 85 ± 4 μm. Further, this multilayer polyimide tubular product had a tensile strength of 26.0 kgf / mm ² and was superior to the multilayer polyimide tubular product of Example 3 in terms of mechanical properties. However, the light transmittances at wavelengths of 550 nm and 780 nm of this multilayer polyimide tubular product are 52.2% and 75.3%, respectively, and this multilayer polyimide tubular product is the multilayer polyimide of Example 3 in terms of light transmission characteristics. It was inferior to a tubular thing. This is because the first polyimide precursor and the second polyimide precursor are individually imidized, resulting in a longer heat treatment time for the first polyimide precursor and a unique yellowing phenomenon of the polyimide. It is considered a thing. Moreover, the boundary part of a 1st polyimide layer and a 2nd polyimide layer was circular arc shape in sectional view, and the mixed layer was not seen. However, no delamination was observed during the back exposure printing test. Further, in this multilayer polyimide tubular product, the repellency phenomenon of the second polyimide precursor solution 57 was locally observed.

  The multilayer polyimide tubular product according to the present invention is a polyimide tubular product capable of having properties such as conductivity, thermal conductivity or light transmission as well as excellent mechanical properties of polyimide, and is an intermediate transfer of an electrophotographic image forming apparatus. It is useful as a member of a belt, a heat fixing belt, a photosensitive drum, or as a medical catheter tube.

It is a schematic diagram of a tandem type color laser beam printer. It is a typical fragmentary sectional view of the film fixing device of a laser beam printer. It is a typical fragmentary sectional view of the double layer structure tubular article concerning an embodiment of the present invention. It is a typical schematic diagram of a film forming device concerning the present invention. 6 is a cross-sectional structure of a multilayer polyimide tubular product according to Example 5. FIG.

Explanation of symbols

21 Intermediate transfer belt 22 Belt pulley 23 Photosensitive drum 24 Exposure scanning device 25 Copy paper 26 Fixing device 30 Multilayer polyimide tubular body 31 Second polyimide resin layer 32 Polyimide resin admixed layer 33 Thermally conductive polyimide resin layer 50 Film forming device 51 Core 52 inner layer polyimide precursor solution molding layer 53 outer layer polyimide precursor solution molding layer 54 first coating molding die 55 second coating molding die 56 first polyimide precursor solution 57 second polyimide precursor solution 58 first pressure tank 59 first 2 Pressurized tank 64 1st distributor 65 2nd distributor 66 1st slit opening 67 2nd slit opening 70 Hanging string Y The pulling-up direction of a core

Claims (4)

A first polyimide resin layer comprising a first polyimide resin;
A second polyimide resin layer comprising a second polyimide resin;
A multilayer polyimide tubular article comprising: a first polyimide resin continuous with the first polyimide resin layer; and a polyimide resin mixed layer in which a second polyimide resin continuous with the second polyimide resin layer is mixed. A polyimide precursor solution overcoating step in which a first polyimide precursor solution, which is a solution of a first polyimide precursor, and a second polyimide precursor solution, which is a solution of a second polyimide precursor, are applied to the outer surface of the core in an overlapping manner. When,
Production of a multilayer polyimide tubular article comprising: an imidization step of imidizing the first polyimide precursor and the second polyimide precursor while removing the solvent from the first polyimide precursor solution and the second polyimide precursor solution Method. A first cylindrical wall having an opening;
A second cylindrical wall having an opening, having an inner peripheral diameter smaller than the inner peripheral diameter of the first cylindrical wall, and disposed below the first cylindrical wall so that the axis is along the axis of the first cylindrical wall When,
A first resin solution delivery unit that delivers the first resin solution or the first resin precursor solution to the opening of the first cylindrical wall; and
An apparatus for producing a multilayer resin tubular product, comprising: a second resin solution solution delivery unit that delivers a second resin solution or a second resin precursor solution to the opening of the second cylindrical wall.   Delivery of the first resin solution or the first resin precursor solution to the opening of the first cylindrical wall by the first resin solution delivery unit is performed by the second resin solution delivery unit or the second resin solution delivery unit. An apparatus for producing a multilayer resin tubular product, further comprising a delivery timing control mechanism that delays delivery of the second resin precursor solution to the opening of the second cylindrical wall.

Images