JP5533818B2 - Heat generating belt for fixing device and image forming apparatus - Google Patents

Description

  The present invention relates to a heat generating belt for a fixing device and an image forming apparatus using the same.

  Conventionally, in image forming apparatuses such as copying machines and laser beam printers, a method in which an unfixed toner image transferred onto an image support such as plain paper is contact-heat-fixed by a heat roller method after toner development is often used. I came.

  However, in the heat roller system, it takes time to heat up to a fixing temperature, and a large amount of heat energy is required. In recent years, the thermal film fixing method has become mainstream from the viewpoint of shortening the time (warming up time) from power-on to copy start and saving energy.

  In this thermal film fixing type fixing device (fixing device), a seamless fixing belt is used in which a release layer such as a fluororesin is laminated on the outer surface of a heat resistant film such as polyimide.

  By the way, in such a fixing device of the thermal film fixing system, for example, the film is heated via a ceramic heater, and the toner image is fixed on the surface of the film. Therefore, the thermal conductivity of the film is an important point. However, if the fixing belt film is made thin to improve the thermal conductivity, the mechanical strength decreases, it becomes difficult to rotate at a high speed, and there is a problem in forming a high-quality image at a high speed. There is also a problem that heaters are easily damaged.

  In order to solve such problems, in recent years, a method has been proposed in which a heating element is provided on the fixing belt itself and the fixing belt is directly heated by supplying power to the heating element to fix the toner image. This type of image forming apparatus has a short warm-up time and lower power consumption than the thermal film fixing system, and is excellent as a thermal fixing apparatus in terms of energy saving and high speed.

  Technological development related to a fixing device using a heat generating belt has been actively conducted so far. As these technologies, for example, the heating element is a heating belt composed of a conductive material such as conductive ceramic, conductive carbon, metal powder, and the like, and an insulating material such as insulating ceramic or heat resistant resin. (For example, refer to Patent Document 1). A heat generating belt having a heat generating layer in which a carbon nanomaterial and filamentary metal fine particles are dispersed in a polyimide resin, an insulating layer, and a release layer is known (for example, see Patent Document 2). It is a fixing device using a heat generating belt having a positive temperature characteristic, and a technology in which a heat generating layer is a conductive oxide and can be mixed with a resin is known (for example, see Patent Document 3).

  However, the techniques described in Patent Document 1 to Patent Document 3 are such that copper-based fillers such as copper, nickel, and silver that can effectively reduce the resistance of the heat generating belt have increased resistance value due to oxidation, safety, and high price. Therefore, sufficient performance as a heat generating belt cannot be maintained over a long period of time. Therefore, the actual situation is that a fixing device using a heat generating belt having a short warm-up time, which is a feature of the heat generating belt, and having energy saving performance has not been developed yet.

  Under such circumstances, the heat-generating fixing belt can be effectively used to reduce the resistance of the heat-generating fixing belt, can maintain a sufficient performance for a long period of time, has a short warm-up time, and has energy-saving performance. And development of an image forming apparatus using the same are desired.

JP 2004-281123 A JP 2007-272223 A JP 2006-350241 A

  The present invention has been made in view of the above situation, and its purpose is to effectively reduce the resistance of the heat generating belt, to maintain sufficient performance over a long period of time, and to shorten the warm-up time and to save energy. The present invention provides a heat-generating fixing belt used in a fixing device having the above and an image forming apparatus using the same.

  The inventor of the present invention paid attention to the effect of reducing resistance (energy saving performance) when using fibers such as metals and graphite, which are inexpensive and stable as a substance, and studied the possibility of practical use. Metals, graphite and the like are extremely stable in the temperature range of 100 ° C. to 200 ° C. used in the fixing belt. In addition, since graphite is composed only of carbon, no problems are found in terms of safety, and there are no problems regarding cost. However, spherical and flat graphite have a problem that the resistance does not decrease as much as low resistance metal fillers such as copper and nickel.

  However, it has been found that the use of a fibrous filler that satisfies certain specific requirements can achieve a resistance lower than that of a metal filler such as silver or nickel. This is presumed that the fiber forms a conductive path without interruption in the heat generation layer as compared with the conventional spherical conductive material, but the resistance is moderately reduced because there is less direct contact between the fillers. The present invention has been made by further study based on these findings.

  That is, it was found that the object of the present invention can be achieved by taking the following configuration.

1. A heat generating belt for a fixing device that heats and fixes a toner image formed using a powder toner after being transferred to an image support, and includes conductive fibers having the following shapes 1 to 3, and carbon black or carbon nanofibers In a heat-resistant resin for a heat generating belt, using graphite fibers as the conductive fibers, the carbon black having a primary particle diameter of 15 nm or more and 50 nm or less, or a diameter A heating belt for a fixing device , wherein the carbon nanofibers having a length of 10 nm or more and 200 nm or less and a length of 0.5 μm or more and 20 μm or less are contained in a polyimide resin as the heat-resistant resin for the heating belt.

1. Aspect ratio: 0.025 ≦ (X / Y) ≦ 0.25
2. Diameter of conductive fiber (X): 0.5 μm ≦ X ≦ 30 μm
3. Conductive fiber length (Y): 5.0μm ≦ Y ≦ 1000μ m

2 . 2. The heat generating belt for a fixing device according to 1 above, wherein the conductive fiber is mixed in an amount of 5.0% by volume to 60% by volume with respect to the polyimide resin.

3 . In an image forming apparatus in which a toner image formed using an image exposure unit and a toner development unit is uniformly charged after the electrophotographic photosensitive member is uniformly charged and then fixed on the image support by a heating and fixing unit. An image forming apparatus using the fixing device heat generating belt as described in 1 or 2 above.

  According to the present invention, it is possible to effectively reduce the resistance of the heat generating belt, maintain a sufficient performance for a long time, and have a short warm-up time and energy saving performance, and an image using the same. A forming device could be provided.

1 is a schematic cross-sectional configuration diagram illustrating an example of an electrophotographic image forming apparatus using a fixing heating belt of the present invention. FIG. 2 is an enlarged schematic view of a fixing device used in the image forming apparatus shown in FIG. 1. FIG. 2 is an enlarged schematic view of the heat fixing belt shown in FIG. 1. FIG. 4 is a schematic manufacturing flow diagram of the heat-generating fixing belt having the configuration shown in FIG. It is the schematic which shows an example of the application | coating / drying apparatus used at the application | coating and drying process of the heat generating layer formation process shown in FIG.

  In conventional fixing devices, heat generating belts for fixing devices in which carbon nanomaterials and filamentary metal fine particles are dispersed in a polyimide resin layer and heat generating belts containing conductive oxides have been proposed. Since a large amount of a compound is added to adjust the resistance to an appropriate electrical resistance, there is a problem that the strength of the heat generating layer is lowered and the durability is deteriorated.

  The feature of the present invention is that the conductive fiber has an electrical resistance close to that of a metal as a conductive material, is less oxidized than copper, and is cheaper than silver or gold and can be used in a wide range. And a carbon black or carbon nanotube to constitute a heat generating layer, and it was possible to provide a heat generating belt with improved durability as well as proper electrical resistance and temperature rise characteristics.

  In the present invention, a conductive fiber having an aspect ratio of 0.025 to 0.25, a diameter of 0.5 μm to 30 μm, and a length of 5.0 μm to 1000 μm and carbon black or carbon nanotubes are polyimide It is a great feature that it is contained in a resin such as.

  The carbon black to be used has a diameter of 3 nm to 500 nm, and the length of the carbon nanotube is 0.5 μm to 20 μm.

  In the present invention, one type of carbon fiber or carbon nanotube is basically used for the conductive fiber as a low resistance material (conductive material) forming the heat generating layer in order to achieve the target resistance value. As a result, a uniform heating belt with low resistance was realized. The conductive fiber contained in the resin is 5.0% by volume or more and 60% by volume or less, and carbon black or carbon nanotube is used by mixing 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the conductive fiber. This is a preferred embodiment of the invention.

  Embodiments of the present invention will be described with reference to FIGS. 1 to 5, but the present invention is not limited thereto.

  FIG. 1 is a schematic sectional view showing an example of an electrophotographic image forming apparatus using the fixing heat generating belt of the present invention. This figure shows the case of a full-color image forming apparatus.

  In the figure, reference numeral 1 denotes a full-color image forming apparatus. The full-color image forming apparatus 1 includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer body forming unit 7 as a transfer unit, and an endless belt-shaped paper feeding conveyance for conveying a recording medium P. And a belt type fixing device 24 as fixing means. A document image reading device SC is arranged on the upper part of the main body A of the full-color image forming apparatus 1.

  An image forming unit 10Y that forms a yellow image as one of different color toner images formed on each of the photoreceptors 1Y, 1M, 1C, and 1K is a drum-like photoreceptor as a first image carrier. 1Y, a charging unit 2Y arranged around the photoreceptor 1Y, an exposure unit 3Y, a developing unit 4Y having a developer carrier 4Y1, a primary transfer roller 5Y as a primary transfer unit, and a cleaning unit 6Y.

  An image forming unit 10M that forms a magenta image as another different color toner image is disposed around a drum-shaped photoconductor 1M as a first image carrier, and the photoconductor 1M. A charging unit 2M, an exposure unit 3M, a developing unit 4M having a developer carrier 4M1, a primary transfer roller 5M as a primary transfer unit, and a cleaning unit 6M.

  Further, an image forming unit 10C for forming a cyan image as one of different toner images of different colors is disposed around a drum-shaped photoreceptor 1C as a first image carrier, and the photoreceptor 1C. The charging means 2C, the exposure means 3C, the developing means 4C having the developer carrier 4C1, the primary transfer roller 5C as the primary transfer means, and the cleaning means 6C are provided.

  In addition, an image forming unit 10K that forms a black image as one of other different color toner images is disposed around a drum-shaped photosensitive member 1K as a first image carrier, and the photosensitive member 1K. It has a charging means 2K, an exposure means 3K, a developing means 4K having a developer carrier 4K1, a primary transfer roller 5K as a primary transfer means, and a cleaning means 6K.

  The endless belt-shaped intermediate transfer body forming unit 7 has an endless intermediate transfer belt 70 as a semiconductive endless belt-shaped second image carrier that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred and synthesized on the rotating endless intermediate transfer belt 70 by the primary transfer rollers 5Y, 5M, 5C, and 5K. A color image is formed. A recording medium P such as paper as a recording medium accommodated in the paper feeding cassette 20 is fed by the paper feeding / conveying means 21, passes through a plurality of intermediate rollers 22 A, 22 B, 22 C, 22 D, and a registration roller 23, and is secondary. A color image is transferred onto the recording medium P at a time by being conveyed to a secondary transfer roller 5A as a transfer means.

  The recording medium P onto which the color image has been transferred is fixed by a fixing device 24 to which an annular heat generating fixing belt 24a is attached, and is sandwiched between paper discharge rollers 25 and placed on a paper discharge tray 26 outside the apparatus. .

  On the other hand, after the color image is transferred to the recording medium P by the secondary transfer roller 5A, the residual toner is removed from the endless intermediate transfer belt 70 from which the recording medium P is separated by the curvature by the cleaning means 6A.

  During the image forming process, the primary transfer roller 5K is always in pressure contact with the photoreceptor 1K. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5A comes into pressure contact with the endless intermediate transfer belt 70 only when the recording medium P passes through the secondary transfer roller 5A and secondary transfer is performed.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R. The housing 8 includes image forming units 10Y, 10M, 10C, and 10K, and an endless belt-shaped intermediate transfer body forming unit 7.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body forming unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1K in the figure. The endless belt-shaped intermediate transfer body forming unit 7 includes an endless intermediate transfer belt 70 that can be rotated by winding rollers 71, 72, 73, 74, and 76, primary transfer rollers 5Y, 5M, 5C, and 5K, and a cleaning unit 6A. And have.

  The image forming units 10Y, 10M, 10C, and 10K and the endless belt-shaped intermediate transfer body forming unit 7 are integrally pulled out from the main body A by the drawer operation of the housing 8.

  In this way, the outer peripheral surfaces of the photoreceptors 1Y, 1M, 1C, and 1K are charged and exposed to form a latent image on the outer peripheral surface, and then a toner image (developed image) is formed by development. The toner images of the respective colors are superposed on each other, transferred onto the recording medium P at once, and fixed and fixed by the belt-type fixing device 24 by pressure and heating. In the present invention, the time of image formation includes latent image formation and transfer of a toner image (developed image) to a recording medium P to form a final image.

  The photoreceptors 1Y, 1M, 1C, and 1K after the toner image is transferred to the recording medium P are transferred by the cleaning units 6Y, 6M, 6C, and 6K disposed on the photoreceptors 1Y, 1M, 1C, and 1K. After cleaning the toner remaining on the photoreceptor, the charging, exposure and development cycle described above is entered, and the next image formation is performed.

  In the color image forming apparatus, an elastic blade is used as a cleaning member of the cleaning unit 6A for cleaning the intermediate transfer member. Further, means (11Y, 11M, 11C, 11K) for applying a fatty acid metal salt to each photoconductor is provided. As the fatty acid metal salt, the same fatty acid metal salt as used in the toner can be used.

  The present invention relates to an annular heat generating and fixing belt 24a used in the fixing device 24 shown in the figure.

  FIG. 2 is an enlarged schematic view of the fixing device used in the image forming apparatus shown in FIG. FIG. 2A is an enlarged schematic perspective view of the fixing device used in the image forming apparatus shown in FIG. FIG. 2B is a schematic cross-sectional view along the line AA ′ shown in FIG.

  In the figure, reference numeral 24 denotes a fixing device. The fixing device 24 includes an annular heat-generating fixing belt 24a, a fixing roller 24b, and a pressure roller 24c that rotates while pressing the annular heat-generating fixing belt 24a.

  The fixing roller 24b serves as a driving roller, and the annular heat-generating fixing belt 24a is wound in the direction of the arrow as the fixing roller 24b rotates (in the direction of the arrow in the figure).

  A fixing nip portion N is formed between the fixing roller 24b and the pressure roller 24c via an annular heat-generating fixing belt 24a. The recording medium P (see FIG. 1) onto which the toner image (visible image) has been transferred is sandwiched at the fixing nip N, and the toner image (visible image) is melted and fixed by the annular heat generating fixing belt 24a to form a final image. It has become.

  The side of the annular heat-generating fixing belt 24a that contacts the fixing roller 24b is the heat-generating layer 24a3 (see FIG. 3), and the side that contacts the pressure roller 24c is the release layer 24a7 (see FIG. 3).

  Reference numeral 24a1 denotes a power supply electrode provided at the end of the heat generating fixing belt 24a, 24a2 denotes a power supply electrode provided at the other end of the heat generating fixing belt 24a, and a pair of the power supply electrode 24a1 and the power supply electrode 24a2 is provided. It has become.

  Reference numeral 24d1 denotes a power supply member that contacts the power supply electrode 24a1 and supplies power to the heat-generating fixing belt 24a. Reference numeral 24d2 denotes a power supply member that contacts the power supply electrode 24a2 and supplies power to the heat-generating fixing belt 24a. In consideration of the temperature of the annular heat-generating fixing belt 24a, fixing stability, and the like, the position where the power supply member is disposed stabilizes the contact between the power supply electrode 24a1 and the power supply member 24d1. A position in contact with 24b and the vicinity of the fixing nip N are preferable.

  In order to bring the power supply member into uniform contact with the power supply electrode, it is preferable to press the power supply electrode with a pressing means (for example, a spring) to make contact.

  FIG. 3 is an enlarged schematic view of the heat-generating fixing belt shown in FIG. FIG. 3A is an enlarged schematic plan view of the heat-generating fixing belt shown in FIG. FIG. 3B is a schematic enlarged cross-sectional view taken along the line BB ′ of FIG. FIG. 3C is an enlarged schematic view of a portion indicated by Y in FIG.

  In the figure, reference numeral 24a denotes an annular heat-generating fixing belt. The annular heat-generating fixing belt 24a has a heat-generating layer 24a3 having power supply electrodes 24a1 and 24a2 at both ends, an elastic layer 24a5 through the primer layer 24a4 except for the power supply electrodes 24a1 and 24a2, and a release through the primer layer 24a6. A layer 24a7. In the present invention, the layer structure is not particularly limited, and the elastic layer 24a5 and the primer layers 24a4 and 24a6 can be provided as necessary.

  In this figure, the surface of the heat generating layer 24a3 opposite to the side where the elastic layer 24a5 is laminated is in contact with the fixing roller 24b (see FIG. 2), and the surface of the release layer 24a7 is in contact with the elastic layer 24a5. The opposite surface is in contact with the pressure roller 24c (see FIG. 2).

  The heat generating layer 24a3 is made of a polyimide resin containing conductive fibers and carbon black or carbon nanotubes (hereinafter also referred to as a conductive substance).

  As the conductive fibers used, the diameter (X) is 0.5 μm ≦ X ≦ 30 μm, the length (Y) is 5.0 μm ≦ Y ≦ 1000 μm, and the aspect ratio is 0.025 ≦ (X / Y) ≦ 0. .25.

  In the present invention, when the diameter of the conductive fiber is less than 0.5 μm, the contact resistance when the fibers are distributed in the heat generating layer and the fibers are in contact with each other becomes too large, and the resistance value of the entire heat generating layer cannot be lowered sufficiently. . On the other hand, when the diameter of the conductive fiber exceeds 30 μm, the dispersibility in the heat generating layer is lowered, and local variation occurs in the resistance. Also, if it is less than 5.0 μm, it is difficult to form a conduction path for electric charges, and if it exceeds 1000 μm, it cannot necessarily exist in an elongated shape, resulting in local variations in resistance of the heat generating layer. Furthermore, even when the aspect ratio is lower than 0.025 or higher than 0.25, any of the above disadvantages occur.

  The diameter and length of the conductive fibers were measured at 500 times using a scanning electron micrograph and the diameter and length of at least 500 fibers were measured from the image captured by the scanner. It calculated from the average value. The aspect ratio was determined by dividing the fiber diameter by the length.

  The mixing amount of the conductive fiber to the polyimide resin is preferably 10% by volume or more and 50% by volume or less with respect to the polyimide resin in consideration of the formation of a conduction path and the strength of the heat generation layer.

  The diameter of carbon black to be used is preferably 3 nm to 500 nm in consideration of the contact point with the conductive fiber.

  The diameter of carbon black is measured by electron microscopy. Electron microscopy is the method shown below. Carbon black is put into chloroform and irradiated with 200 kHz ultrasonic waves for 20 minutes to disperse, and then the dispersed sample is fixed to the support membrane. This is photographed with a transmission electron microscope, and the particle diameter is calculated from the diameter on the photograph and the magnification of the photograph. This operation is performed about 1500 times, and the value measured by the arithmetic average of these values is shown.

  The amount of carbon black used is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the conductive fiber in consideration of the strength of the heat generating layer.

  The length of the carbon nanofiber is preferably 0.5 μm to 20 μm in consideration of contact with the conductive fiber.

  The fiber diameter and length are measured by electron microscopy. Electron microscopy is the method shown below. Carbon black is put into chloroform and irradiated with 200 kHz ultrasonic waves for 20 minutes to disperse, and then the dispersed sample is fixed to the support membrane. This is photographed with a transmission electron microscope, and the fiber diameter and length are calculated from the diameter on the photograph and the magnification of the photograph. This operation is performed about 500 times and the value measured by the arithmetic average of these values is shown.

  The formation of the power feeding electrodes 24a1 and 24a2 is not particularly limited. For example, a conductive tape may be bonded.

  The hardness of the release layer 24a7 is universal hardness (HU) (DIN 50359), and is preferably 50 MPa to 800 MPa in consideration of durability, flexibility, releasability, toner offset property and the like. The hardness of the release layer 24a7 is a value measured using an ultra micro hardness meter “H-100V (manufactured by Fisher Instruments Co., Ltd.)”.

  The friction coefficient of the release layer 24a7 is preferably 0.25 or less in consideration of release properties, toner offset properties, durability, and the like. The coefficient of friction indicates a value measured using a portable friction meter “Muse TIPE: 94i-II (manufactured by Shinto Kagaku Co., Ltd.)”.

  The measurement is performed on the release layer 24a7 at random from 10 to 30 points, and the average value thereof is defined as the friction coefficient (μ).

  E indicates the thickness of the heat generating layer. The thickness E is preferably 0.02 mm to 0.2 mm in consideration of electrothermal properties and flexibility. Thickness E shows the value measured with Otsuka Electronics Co., Ltd. FE-300.

  F indicates the thickness of the elastic layer 24a5. The thickness F is preferably 0.1 mm to 0.3 mm in consideration of flexibility. Thickness F shows the value measured with Otsuka Electronics Co., Ltd. FE-300.

  G indicates the thickness of the release layer 24a7. The thickness G is preferably 1 μm to 10 μm and more preferably 1 μm to 5 μm in consideration of heat transfer properties, flexibility, durability, and the like. The thickness indicates a value measured by an eddy current film thickness meter (manufactured by Fisher Instruments Co., Ltd.).

  The primer layers 24a4 and 24a6 preferably have a thickness of 2 μm to 5 μm.

  The width and diameter of the heat fixing belt 24a can be determined as appropriate according to the specifications of the image forming apparatus.

The volume resistivity of the heat generation layer 24a3 is poor in heat generation efficiency regardless of whether the volume resistivity is high or low, and is preferably 8 × 10 ⁻⁶ Ω · m to 1 × 10 ⁻² Ω · m in consideration of heat generation efficiency.

  The volume resistivity can be calculated by the following equation by providing electrode portions with conductive tape at both ends of the heat-generating fixing belt in the circumferential direction and measuring the resistance values at both ends.

Volume resistivity (ρ) = (R · d · W) / L (Ω · m)
(However, the resistance value between both ends (R: Ω), the heat generation layer thickness (d: m), the circumferential length (W: m), and the length between electrodes (L: m).)
Next, a method of manufacturing the heat fixing belt shown in FIGS. 1 to 3 will be described.

  FIG. 4 is a schematic manufacturing flow diagram of the heat-generating fixing belt having the configuration shown in FIG.

  The heat generating fixing belt 24a can be manufactured by two manufacturing flows shown in FIGS.

  This will be described with reference to a schematic manufacturing flow diagram shown in FIG.

  Reference numeral 9 denotes a manufacturing process. The manufacturing process 9 includes a heat generating layer forming process 9A, an elastic layer forming process 9B, and a release layer forming process 9C.

  The heating layer forming step 9A includes a dissolving step 9a, a conductive material dispersing step 9b, a coating / drying step 9c, and a firing step 9d.

  In the dissolution step 9a, a tetracarboxylic dianhydride and a diamine compound are dissolved in a substantially equimolar amount in a solvent, mixed and heated, and subjected to a polycondensation reaction to prepare a polyamic acid solution.

  In the conductive substance dispersing step 9b, a conductive substance is added to the polyamic acid solution prepared in the dissolving step 9a, and the mixture is heated and stirred to prepare conductive fibers and a conductive substance-dispersed polyamic acid solution.

  The solid content concentration of the polyamic acid solution is not particularly defined, but a range in which an appropriate viscosity is expressed is selected depending on the coating suitability at the time of manufacturing the annular heat-generating fixing belt made of polyimide resin. The viscosity range optimum for coating is generally preferably from 1 Pas to 100 Pas.

  As a method for dispersing the conductive substance, a known method can be applied, and examples thereof include a ball mill, a sand mill, a basket mill, and ultrasonic dispersion.

  Further, when the conductive substance is dispersed, it is preferable to add a nonionic polymer in order to further improve the dispersion stability. Nonionic polymers include poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylazide), poly (N-vinylformamide), poly (N-vinylacetamide), poly (N -Vinylphthalamide), poly (N-vinylsuccinamide), poly (n-vinylurea), poly (N-vinylpiperidone), poly (n-vinylcaprolactam), poly (n-vinyloxazoline), and the like. A single or a plurality of nonionic polymers can be added. In these, since the dispersibility of an electroconductive substance improves more, it is more preferable that poly (n-vinyl- 2-pyrrolidone) is included.

  In the coating / drying step 9c, the conductive material-dispersed polyamic acid solution prepared in the conductive material dispersing step 9b is applied to a cylindrical mold and dried.

  There is no particular limitation on the coating method. For example, when a cylindrical mold is used, a dip coating method, a coating method using a nozzle, and the like can be mentioned, which can be used as necessary. The application method using the nozzle will be described with reference to FIG.

  For drying, a cylindrical mold coated with a conductive material-dispersed polyamic acid solution is placed in a heating environment, and 20 mass% to 60 mass% or more of the contained solvent is volatilized to form a heat-generating fixing belt coating film (conductive material). This is performed to form a dispersed polyamic acid coating film). At this time, the solvent may remain in the film, and there is no problem as long as the surface does not flow even if the surface of the heat-generating fixing belt-forming coating film (conductive substance-dispersed polyamic acid coating film) is inclined. Drying is preferably performed in a temperature range of 50 ° C. to 200 ° C. under normal pressure.

  In the firing step 9d, after drying in the drying step is finished, the cylindrical mold on which the heat-generating fixing belt-forming coating film (conductive substance-dispersed polyamic acid coating film) is formed is heated in a temperature range of 200 ° C to 500 ° C. And the imide conversion reaction proceeds sufficiently. When the heating temperature is less than 60 ° C., dehydration ring closure does not proceed sufficiently, and when the heating temperature exceeds 500 ° C., decomposition starts. The imidization temperature varies depending on the types of raw material tetracarboxylic dianhydride and diamine, or added tertiary amine, but must be set to a temperature at which imidization is completed. Insufficient imidization may result in poor mechanical and electrical properties.

  Due to the dehydration ring closure reaction of the polyamic acid, conversion from polyamide to polyimide occurs. As a result, a mass decrease corresponding to the amount of water desorbed by the reaction occurs, and the content of the conductive material relative to the polyimide resin component in the heat-generating fixing belt-forming coating film (conductive material-dispersed polyamic acid coating film) It becomes large compared with the electroconductive substance content rate with respect to a polyamic-acid resin component.

  The elastic layer forming step 9B includes an application step (not shown) and a drying step (not shown). In the elastic layer forming step 9B, an elastic layer is formed by applying an elastic layer forming coating solution on the heat generating layer except for the power feeding electrodes 24a1 and 24a2 (see FIG. 3) and then drying. In order to improve the adhesion between the elastic layer and the heat generating layer, it is preferable to form the elastic layer after forming the primer layer.

  The release layer forming step 9C includes an application step (not shown) and a drying step (not shown). In the release layer forming step 9C, the release layer is formed by applying a release layer forming coating solution on the elastic layer except for the power feeding electrodes 24a1 and 24a2 (see FIG. 3) and then drying. In order to improve the adhesion between the elastic layer and the release layer, it is preferable to form the release layer after forming the primer layer.

  Thereafter, by extracting the cylindrical mold, an annular heat generating fixing belt in which a heat generating layer containing a conductive material, an elastic layer, and a release layer are sequentially formed can be manufactured. The elastic layer and the release layer can be omitted as necessary.

  The power feeding electrodes 24a1 and 24a2 (see FIG. 3) can be formed by bonding a conductive tape to both ends of the heat generation layer using a tape bonding machine after forming the release layer. is there.

  This will be described with reference to a schematic manufacturing flow diagram shown in FIG.

  9 'shows a manufacturing process. The manufacturing process 9 'includes a heat generating layer forming process 9'A, an elastic layer forming process 9'B, and a release layer forming process 9'C. The heat generating layer forming step 9'A includes a conductive material dispersing step 9'a, a polycondensation step 9'b, a coating / drying step 9'c, and a firing step 9'd.

  In the conductive material dispersion step 9'a, the conductive material is dispersed in the solvent. In addition, the solvent to be used is the same solvent as the solvent used in the dissolving step 9a of the heat generating layer forming step 9A shown in (a).

  In the polycondensation step 9′b, substantially equimolar amounts of tetracarboxylic dianhydride and diamine compound are dissolved in the conductive material dispersion prepared in the conductive material dispersion step 9′a, and mixed and heated. Then, a polycondensation reaction is performed to prepare a conductive material-dispersed polyamic acid solution. In the conductive material-dispersed polyamic acid solution, the blending amount of the conductive material is the same as that in the manufacturing process 9 shown in (a).

  In the coating / drying step 9'c, the conductive material-dispersed polyamic acid solution prepared in the polycondensation step 9'b is applied to a cylindrical mold and dried. The coating method and drying conditions are the same as those in the coating / drying step 9c of the manufacturing step 9 shown in FIG.

  In the firing step 9'd, after drying in the drying step is completed, the cylindrical mold on which the heat-generating fixing belt-forming coating film (conductive substance-dispersed polyamic acid film) is formed is fired to sufficiently perform the imide conversion reaction. Make it progress. The firing conditions are the same as the firing step 9d of the manufacturing step 9 shown in (a).

  The elastic layer forming step 9'B has a coating step (not shown) and a drying step (not shown). In the elastic layer forming step 9'B, the elastic layer is formed by applying an elastic layer forming coating solution on the heat generating layer except for the power feeding electrodes 24a1 and 24a2 (see FIG. 3) and then drying. In order to improve the adhesion between the elastic layer and the heat generating layer, it is preferable to form the elastic layer after forming the primer layer. The elastic layer forming coating solution can be applied in the same manner as the heating layer forming coating solution.

  The release layer forming step 9'C has a coating step (not shown) and a drying step (not shown). In the release layer forming step 9'C, a release layer is formed by applying a release layer forming coating solution on the elastic layer except for the feeding electrodes 24a1 and 24a2 (see FIG. 3) and then drying. The In order to improve the adhesion between the elastic layer and the release layer, it is preferable to form the release layer after forming the primer layer. The release layer forming coating solution can be applied by the same method as the heating layer forming coating solution.

  Thereafter, by extracting the cylindrical mold, an annular heat generating fixing belt in which a heat generating layer containing a conductive material, an elastic layer, and a release layer are sequentially formed can be manufactured. The elastic layer and the release layer can be omitted as necessary.

  The power feeding electrodes 24a1 and 24a2 (see FIG. 3) can be formed by bonding a conductive tape to both ends of the heat generation layer using a tape bonding machine after forming the release layer. is there.

  FIG. 5 is a schematic view showing an example of a coating / drying apparatus used in the coating / drying step of the heat generating layer forming step shown in FIG. FIG. 5A is a schematic perspective view showing an example of a coating / drying apparatus used in the coating / drying step of the heat generating layer forming step shown in FIG. FIG. 5B is a schematic front view of the coating / drying apparatus shown in FIG. A method for applying a conductive substance-dispersed polyamic acid solution on the surface of a cylindrical mold using a cylindrical mold will be described below.

  In the figure, 9c1 indicates a coating apparatus. The coating device 9c1 includes a holding unit 9c11, a coating unit 9c12, and a drying unit 9c13. The holding unit 9c11 includes a first holding table 9c111, a second holding table 9c112, and a driving motor 9c113. The driving motor 9c113 is disposed on the first holding base 9c111, and is connected to the rotating shaft of the driving motor 9c113 via the holding member 9c21 and the connecting member of the cylindrical mold 9c2. A receiving portion 9c114 for receiving the other holding member 9c22 of the cylindrical mold 9c2 is disposed on the second holding base 9c112, whereby the cylindrical mold 9c2 can be rotated and stopped by the rotation of the driving motor 9c113. It can be held as possible.

  The coating unit 9c12 includes a coating unit 9c121 and a driving unit 9c122. Reference numeral 9c123 denotes a coating liquid supply pipe for supplying a conductive substance-dispersed polyamic acid solution to the coating means 9c121. The application means 9c121 is attached to the guide rail 9c125 by an attachment member 9c124 so as to be movable in parallel along the rotation axis of the cylindrical mold 9c2. An example of the application unit 9c121 is a nozzle. The shape of the discharge port of the conductive material-dispersed polyamic acid solution of the nozzle is not particularly limited, and examples thereof include a circle and a rectangle. The distance from the nozzle outlet to the peripheral surface of the cylindrical mold 9c2 is preferably 1 mm to 100 mm in consideration of the viscosity, film thickness, etc. of the coating solution. In this figure, the conductive material-dispersed polyamic acid solution supply unit and the control unit for the coating means 9c121 are omitted.

  The drive means 9c122 has a motor 9c126 and a guide rail mounting plate 9c3. An attachment member 9c124 is attached to the guide rail attachment plate 9c3, and the coating means 9c121 is reciprocated in the direction of the rotation axis (in the direction of the arrow in the figure) parallel to the rotation axis of the cylindrical mold c2 held by the holding portion 9c11. Two guide rails 9c125 are provided for this purpose.

  The motor 9c126 is screwed into a slide screw 9c127 mounted on the mounting member 9c124, and the female screw has a length that moves the mounting member 9c124 longer than the width of the cylindrical mold 9c2 held by the holding portion 9c11. 9c128.

  By driving the motor 9c126, the application means 9c121 attached to the attachment member 9c124 reciprocates in the direction of the rotation axis parallel to the rotation axis of the cylindrical mold 9c2 as the female screw 9c128 rotates (in the direction of the arrow in the figure). ) Is possible.

  After the conductive material-dispersed polyamic acid coating film (heat-generating fixing belt forming coating film) is formed on the cylindrical mold 9c2, the conductive material-dispersed polyamic acid coating film (heat-generating fixing belt forming coating film) is dried. The solvent is removed while rotating in the section 9c13. Thereafter, a polyimide film is formed by performing a heat treatment in a baking step (not shown). Thereafter, an annular heat generating fixing belt is formed by removing the cylindrical mold 9c2.

  The drying unit 9c13 has a drying device 9c131. The drying device 9c131 is disposed under the cylindrical mold 9c2 in order to dry the conductive material-dispersed polyamic acid solution coating film applied to the cylindrical mold 9c2. Examples of the heat source of the drying device 9c131 include a heat source such as an infrared lamp, a nichrome wire, and hot air. The drying device 9c131 can also be used as a baking device after removing the solvent of the conductive material-dispersed polyamic acid coating film (coating film for forming the heat fixing belt).

  Although this figure shows the case where a cylindrical mold is used, it may be a cylindrical mold and can be appropriately selected.

  This figure describes the application method using a nozzle, but the method for applying the conductive material-dispersed polyamic acid solution (heating fixing belt forming solution) to the surface of the cylindrical mold 9d is not particularly limited. And a known coating method can be applied. Examples thereof include an annular coating method using an annular coating tank, a dip coating method, and a coating method using an ultrasonic atomizer.

  Even when the elastic layer and the release layer are sequentially formed on the formed heat fixing belt, the elastic layer forming solution and the release layer forming solution are heated and fixed using the coating apparatus 9c1 shown in this figure. It can be formed by sequentially coating on a belt.

  The viscosity of the conductive material-dispersed polyamic acid solution (exothermic fixing belt forming solution) used in the present invention is 5 Pa · s in consideration of coating properties to a cylindrical mold, leveling properties, handling properties such as defoaming, and the like. To 200 Pa · s is preferable. The viscosity indicates a value measured at a temperature of 25 ° C. using TVB10 type manufactured by Toki Sangyo Co., Ltd.

The diameter (A) of the conductive fiber is 0.5 μm ≦ A ≦ 30 μm, the length (B) of the conductive fiber is 5.0 μm ≦ B ≦ 1000 μm, and the aspect ratio is 0.025 ≦ (A / B) ≦. The following effects can be obtained by a heat-generating fixing belt having a heat-generating layer composed of a polyimide resin containing 0.25 conductive fibers and carbon black or carbon nanofibers.
1. The resistance of the heat generating belt can be effectively reduced, and sufficient performance can be maintained over a long period of time.
2. Warming up time can be shortened.
3. An image forming apparatus with a short warm-up time and energy saving performance can be produced.

  Next, materials relating to each layer constituting the heat-generating fixing belt of the present invention will be described.

Heat generation layer (heat resistant resin)
In the present invention, a so-called heat-resistant resin is used as the binder resin for forming the heat generating layer, and generally a resin having a short-term heat resistance of 200 ° C. or higher and a long-term heat resistance of 150 ° C. or higher is referred to as a heat-resistant resin. The following are mentioned as a typical thing of heat resistant resin. For example, polyphenylene sulfide (PPS), polyarylate (PAR), polysulfone (PSF), polyethersulfone (PES), polyetherimide (PEI), polyimide (PA), polyamideimide (PAI), polyether ether ketone ( PEEK) resin and the like. Among these, a particularly preferable heat resistant resin is a polyimide resin.

  In the present invention, it is highly desirable that 40% by volume or more of the entire resin is the resin.

(Polyimide resin)
In the polyimide resin, a polyamic acid obtained by polymerizing at least one kind of aromatic diamine and at least one kind of aromatic tetracarboxylic dianhydride in an organic polar solvent is usually imide-converted to form a polyimide resin.

(Diamine compound)
The diamine compound used for producing the polyamic acid is not particularly limited as long as it is a diamine compound having two amino groups in the molecular structure.

  For example, paraphenylenediamine (PPD), metaphenylenediamine (MPDA), 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'- Biphenyl, 3,3'-dimethoxy-4,4'-biphenyl, 2,2-bis (trifluoromethyl) -4, 4'-diaminobiphenyl, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane (MDA), 2,2-bis- (4-aminophenyl) propane, 3,3'-diaminodiphenylsulfone (33DDS), 4,4'-diaminodiphenylsulfone (44DDS), 3,3'-diaminodiphenylsulfide 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ether, 3, '-Diaminodiphenyl ether (34 ODA), 4,4'-diaminodiphenyl ether (ODA), 1,5-diaminonaphthalene, 4,4'-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'- Diaminodiphenylethylphosphine oxide, 1,3-bis (3-aminophenoxy) benzene (133APB), 1,3-bis (4-aminophenoxy) benzene (134APB), 1,4-bis (4-aminophenoxy) benzene Bis [4- (3-aminophenoxy) phenyl] sulfone (BAPSM), bis [4- (4-aminophenoxy) phenyl] sulfone (BAPS), 2,2-bis [4- (4-aminophenoxy) phenyl Propane (BAPP), 2,2-bis (3-aminopheny) ) 1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) 1,1,1,3,3,3-hexafluoropropane and 9,9-bis ( 4-aminophenyl) fluorene and the like. Among them, preferable diamines are paraphenylenediamine (PPD), metaphenylenediamine (MPDA), 4,4'-diaminodiphenylmethane (MDA), 3,3'-diaminodiphenylsulfone (33DDS), 4,4'-diaminodiphenylsulfone. (44DDS), 3,4'-diaminodiphenyl ether (34ODA), 4,4'-diaminodiphenyl ether (ODA), 1,3-bis (3-aminophenoxy) benzene (133APB), 1,3-bis (4- Aminophenoxy) benzene (134APB), bis [4- (3-aminophenoxy) phenyl] sulfone (BAPSM), bis [4- (4-aminophenoxy) phenyl] sulfone (BAPS), 2,2-bis [4- (4-Aminophenoxy) phenyl] propane ( Aromatic diamine such as APP): aromatic diamine having two amino groups bonded to an aromatic ring such as diaminotetraphenylthiophene and a hetero atom other than the nitrogen atom of the amino group: 1,1-metaxylylenediamine 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadieny Aliphatic diamines and fats such as range amine, hexahydro-4,7-methanoin danylene dimethylene diamine, tricyclo [6,2,1,02.7] -undecylene dimethyl diamine, 4,4'-methylene bis (cyclohexylamine) Cyclic diamine, etc. It can gel.

  Among these diamine compounds, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, and 4,4'-diaminodiphenyl sulfone are preferable.

  These diamine compounds can be used alone or in combination of two or more.

(Tetracarboxylic dianhydride)
There is no restriction | limiting in particular as tetracarboxylic dianhydride which can be used for manufacture of a polyamic acid, Both an aromatic type and an aliphatic type compound can be used.

  Representative examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride (PMDA), 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetra. Carboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'- Biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,2', 3,3'-benzophenone tetracarboxylic acid dihydrate, 2,3 , 3 ', 4'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA), bis (3,4-dicarboxyphenyl) sulfone dianhydride , Bi (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1, 1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 2,2-bis [3,4- (dicarboxyphenoxy) phenyl] propane dianhydride (BPADA), 4,4 '-(hexafluoro) Isopropylidene) diphthalic anhydride, oxydiphthalic anhydride (ODPA), bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) sulfoxide dianhydride, thiodiphthalic dianhydride 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8 Phenanthrenetetracarboxylic dianhydride, 9,9-bis (3,4-dicarboxyphenyl) fluorene dianhydride and 9,9-bis [4- (3,4'-dicarboxyphenoxy) phenyl] fluorene dianhydride And the like. Among them, preferred tetracarboxylic dianhydrides are pyromellitic dianhydride (PMDA), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-. Examples include benzophenone tetracarboxylic dianhydride (BTDA), 2,2-bis [3,4- (dicarboxyphenoxy) phenyl] propane dianhydride (BPADA), and oxydiphthalic anhydride (ODPA). These may be reacted with alcohols such as methanol and ethanol to form ester compounds.

  Aliphatic tetracarboxylic dianhydrides include butane tetracarboxylic dianhydride, 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane. Tetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxynorbonane-2-acetic acid dianhydride Anhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, An aliphatic or alicyclic tetracarboxylic dianhydride such as bicyclo [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; 4 5,9B-Hexahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5-methyl -5- (Tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl Examples include aliphatic tetracarboxylic dianhydrides having an aromatic ring such as -5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione. Can do.

  As tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride is preferable, and pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3, 3 ', 4,4'-biphenylsulfone tetracarboxylic dianhydride is optimally used.

  These aromatic diamines and aromatic tetracarboxylic dianhydrides or aliphatic tetracarboxylic dianhydrides can be used alone or in combination. It is also possible to prepare a plurality of types of polyamic acid solutions and to use these mixed polyamic acid solutions.

  As a solvent used for preparing the polyamic acid solution, N, N-dimethylformamide (DMF) or N-methyl-2-pyrrolidone (NMP) can be used.

(Conductive fiber)
The conductive fiber is typically a pure metal fiber such as gold, silver, iron, or aluminum, an alloy fiber such as stainless steel or nichrome, or a non-metallic fiber such as carbon or graphite. The fiber has an elongated shape. This is a designation indicating that In the present invention, graphite fibers are particularly preferable conductive fibers.

  As a method for producing these fibers, a known production method described in JP-A No. 2004-176236 can be used.

These conductive fibers themselves preferably have a volume resistivity (ρv) of 10 ⁻¹ Ω · m or less.

  The volume specific resistance (ρv) is obtained by the following equation by passing a constant current I through the cross-sectional area Wt and measuring the potential difference V (V) between the electrodes separated by the distance L.

Volume resistivity ρv = VWt / IL
(Carbon black)
Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Of these, preferred.

  As a method for producing these carbon blacks, a known production method described in Carbon Black Handbook Edit: Carbon Black Association, etc. can be used.

(Carbon nanomaterial)
Examples of the carbon nanomaterial include carbon nanofiber and carbon microcoil, and carbon nanofiber is particularly preferable.

  The method for producing these carbon nanofibers is described by Soneda Satoshi Carbon No. 237 72-76 (2009) can be used.

(Elastic layer)
The elastic layer is not particularly limited, and any rubber material or thermoplastic elastomer can be used. For example, styrene-butadiene rubber (SBR), high styrene rubber, polybutadiene rubber (BR), polyisoprene rubber (IIR), ethylene-propylene copolymer, nitrile butadiene rubber, chloroprene rubber (CR), ethylene-propylene-diene rubber (EPDM) ), Butyl rubber, silicone rubber, fluorine rubber, nitrile rubber, urethane rubber, acrylic rubber (ACM, ANM), epichlorohydrin rubber, norbornene rubber, and the like. These may be used alone or in combination of two or more.

  On the other hand, as the thermoplastic elastomer, polyester, polyurethane, styrene-butadiene triblock, polyolefin, and the like can be used.

  In addition, various compounding agents such as a filler, an extender filler, a vulcanizing agent, a colorant, a heat-resistant agent, and a pigment should be added to the elastic layer depending on the purpose of use and design of the heat-generating fixing belt. I can do it. Although the plasticity of the synthetic resin varies depending on the amount of the compounding agent added, the plasticity of the rigid resin before curing is preferably 120 or less.

(Release layer)
The release layer forming resin is selected from the group consisting of polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). It is preferred that there is at least one resin.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
(Preparation of conductive fiber, carbon black, and carbon nanofiber-dispersed polyamic acid solution)
Filler shown in Table 1 is added to 100 g of a polyamic acid solution (U-Vanice S301, manufactured by Ube Industries Co., Ltd.), which is a polyimide resin precursor, and stirring and mixing are performed using a TK homodisper type 2.5 manufactured by Primix. , 15 minutes at 1,000 rpm. The graphite fiber was produced by the method described in JP-A-2004-176236, and the diameter and length were changed by changing the spinning conditions and the classification conditions.

(Formation of heat generation layer)
The prepared dispersions of Examples 1 to 20 and Comparative Examples 1 to 9 and the mixed solution were used in the manufacturing apparatus shown in FIG. 5, and the thickness of the stainless steel core attached to the coating apparatus was 0.8 mm. After coating under the conditions shown below, it was heated and dried at 120 ° C. for 40 minutes while rotating at a rotation speed of 40 rpm. Thereafter, the mixture was heated and dried at 400 ° C. for 20 minutes to form a heat generation layer of the heat fixing belt. Subsequently, a feeding electrode, an elastic layer, and a release layer were formed without removing the cored bar.

Application condition Polyamide acid solution temperature: 25 ° C
Shape of the polyamic acid solution outlet of the nozzle: conical nozzle Diameter of the polyamic acid solution outlet of the nozzle: 2 mm
Distance between nozzle polyamic acid solution outlet and core metal peripheral surface: 5 mm
Discharge amount of polyamic acid solution from nozzle: 5 ml / min
Movement speed of the nozzle core in the direction of the rotation axis: 1 mm / sec
Rotating speed of cored bar: 40rpm
The rotation speed of the core bar indicates a value measured by HT-4200 manufactured by Ono Sokki Co., Ltd.

(Formation of feeding electrode)
One turn of conductive tape CU-35C (manufactured by 3M Co., Ltd.) having a width of 10 mm and a thickness of 2 mm was attached to both peripheral surfaces of the heat generating layer (polyimide resin) to form a power feeding electrode.

(Formation of elastic layer)
(Preparation of coating solution for elastic layer formation)
40 g of a composition in which two liquids of silicone rubber KE1379 (manufactured by Shin-Etsu Chemical Co., Ltd.) and silicone rubber DY356013 (manufactured by Toray Dow Corning Silicone) were mixed in a ratio of 2: 1 was used as an elastic layer forming coating liquid. did. The viscosity was 50 Pa · s measured using a TVB10 model manufactured by Toki Sangyo Co., Ltd. at a temperature of 25 ° C.

(Application of elastic layer forming coating solution)
Using the manufacturing apparatus shown in FIG. 5, instead of the polyimide precursor coating solution, the polyimide layer precursor is formed on the heat generating layer except for the elastic layer forming coating solution on the power supply electrode under the following conditions. The elastic layer forming coating solution is applied by the same method as the application of the body coating solution to form an elastic layer forming coating film having a thickness of 200 μm after drying. Thereafter, primary vulcanization was performed at 150 ° C. for 30 minutes while the cored bar was rotated at a rotation speed of 40 rpm, and post-vulcanization was further performed at 200 ° C. for 4 hours, thereby forming an elastic layer on the heat generating layer.

Coating conditions Elastic layer forming coating solution temperature: 25 ° C
Shape of coating liquid discharge port for forming elastic layer of nozzle: Conical nozzle Diameter of coating solution discharge port for forming elastic layer of nozzle: 2 mm
Distance from the coating liquid discharge port for forming the elastic layer of the nozzle to the peripheral surface of the heat generating layer: 5 mm
Discharge amount of the coating liquid for forming the elastic layer from the nozzle: 5 ml / min
Movement speed of the nozzle core in the direction of the rotation axis: 1 mm / sec
Rotating speed of cored bar: 40rpm
The rotation speed of the core bar indicates a value measured by HT-4200 manufactured by Ono Sokki Co., Ltd.

(Formation of release layer)
(Preparation of release layer forming coating solution)
A PTFE resin and PFA resin were mixed at a ratio of 7: 3, and a release layer was formed using a fluororesin dispersion (trade name “855-510” manufactured by DuPont) adjusted to a solid content concentration of 45% and a viscosity of 110 mPa · s. It was prepared as a coating solution.

(Application of release layer forming coating solution)
Using the manufacturing apparatus shown in FIG. 5, instead of the elastic layer forming coating solution, the release layer forming coating solution is formed on the elastic layer except for the power supply electrode under the following conditions. The release layer forming coating solution is applied in the same manner as the application of the coating solution for forming a release layer, and a release layer forming coating film having a thickness of 30 μm after drying is formed. Thereafter, after drying at room temperature for 30 minutes, the cored bar is heated at 230 ° C. for 30 minutes while rotating at a rotational speed (circumferential speed) of 0.1 m / sec, and further heated at 270 ° C. for 10 minutes. A release layer was formed on top.

  The tensile strength of the release layer was 10 MPa. As for the tensile strength of the release layer, the hardness of the release layer is a value measured using 5988 manufactured by Instron Japan Company Limited.

  The coefficient of friction of the release layer was 0.1. The coefficient of friction indicates a value measured using a portable friction meter “Muse TIPE: 94i-II (manufactured by Shinto Kagaku Co., Ltd.)”. The measurement is performed on the release layer at random from 10 to 30 points, and the average value thereof is defined as the friction coefficient (μ).

Coating conditions: Temperature of coating solution for forming release layer: 25 ° C
Shape of coating liquid discharge port for forming release layer of nozzle: Conical nozzle Diameter of coating liquid discharge port for forming release layer of nozzle: 2 mm
Distance from the coating liquid discharge port for forming the release layer of the nozzle to the peripheral surface of the heating layer: 5 mm
Discharge rate of release layer forming coating solution from nozzle: 5 ml / min
The moving speed of the nozzle core in the direction of the rotation axis: 1 mm / min
Rotating speed of cored bar: 40rpm
The rotation speed of the core bar indicates a value measured by HT-4200 manufactured by Ono Sokki Co., Ltd.

(Withdrawing the core)
After the release layer was formed, the cored bar was cooled and removed to prepare a heat-generating fixing belt shown in Table 7 having the structure shown in FIG. 3 (heat-generating layer / elastic layer / release layer).

Evaluation The produced belts of Examples 1 to 14 , Reference Examples 1 to 6, and Comparative Examples 1 to 9 were loaded into the image forming apparatus shown in FIG. 2 and incorporated in the image forming apparatus shown in FIG. Pass through 10,000 sheets every 10,000 sheets for 5 minutes and observe the following methods for resistivity, temperature rise, fixability, and oxidation of conductive fibers, and according to the rating rank shown below. The evaluation results are shown in Table 1.

(Measurement method of resistivity)
The resistance was measured with a Loresta AX MCP-T370 model manufactured by Mitsubishi Chemical Analytech. In the heat-generating fixing belt according to the present invention, a preferable resistivity when measured by the resistivity measurement method is 7Ω to 50Ω.

(Method for measuring temperature rise)
With the temperature rise property, the temperature up to 5 seconds after energization when 10 V was applied to the heat generation layer was measured with a thermo viewer.

Rank of evaluation of temperature rise ◎: Extremely excellent at 16 ° C / second or more ○: 8 ° C / second or more, less than 16 ° C / second △: 4 ° C / second or more, less than 8 ° C / second Practical level ×: 4 ° C Less than 1 sec / sec, a level that is problematic for practical application (fixing measurement method)
Fixability is the degree of toner fixing when a toner image formed using powder toner is transferred to an image support and then heat-fixed by a heat generating belt. When the cotton pad was pressed and rubbed against the black toner solid image, the toner moved to the cotton cloth, or when the toner solid image was strongly bent ten times, the state of the image at the crease portion was observed.

Evaluation rank of fixing property ○: No abnormality at all when rubbing or bending. Δ: When rubbing, the cotton cloth is slightly dirty, but there is no problem in practical use. ×: When rubbing, the cotton cloth is dirty and the toner is bent. Floats and has practical problems (Durability measurement method)
With respect to durability, the fixability after passing 500,000 sheets of the image support was measured by the same method as the fixability measurement method, and evaluated with the same evaluation rank as the fixability evaluation rank.

DESCRIPTION OF SYMBOLS 1 Full color image forming apparatus 7 Endless belt-shaped intermediate transfer body formation unit 70 Intermediate transfer belt 24 Fixing device 24a Heat generating fixing belt 24a1, 24a2 Power supply electrode 24a3 Heat generating layer 24a4, 24a6 Primer layer 24a5 Elastic layer 24a7 Release layer 9, 9 ' Manufacturing process 9A, 9'A Heat generation layer forming process 9a Dissolution process 9b, 9'a Conductive substance dispersion process 9'b Polycondensation process 9c, 9'c Coating / drying process 9c1 Coating device 9c11 Holding section 9c12 Coating section 9c121 Coating Means 9c123 Coating solution supply pipe 9c13 Drying section 9c2 Cylindrical mold 9d, 9'd Firing step 9B, 9'B Elastic layer forming step 9C, 9'C Release layer forming step

Claims (3)

A heat generating belt for a fixing device that heats and fixes a toner image formed using a powder toner after being transferred to an image support, and includes conductive fibers having the following shapes 1 to 3, and carbon black or carbon nanofibers And a heat generating belt for a fixing device,
The carbon black having a primary particle diameter of 15 nm or more and 50 nm or less, or a carbon nanofiber having a diameter of 10 nm or more and 200 nm or less, and a length of 0.5 μm or more and 20 μm or less, using graphite fibers as the conductive fibers. Is contained in a polyimide resin as the heat resistant resin for the heat generating belt.
1. Aspect ratio: 0.025 ≦ (X / Y) ≦ 0.25
2. Diameter of conductive fiber (X): 0.5 μm ≦ X ≦ 30 μm
3. Length of conductive fiber (Y): 5.0 μm ≦ Y ≦ 1000 μm 2. The heat generating belt for a fixing device according to claim 1, wherein the conductive fiber is mixed in an amount of 5.0% by volume to 60% by volume with respect to the polyimide resin. In an image forming apparatus in which a toner image formed using an image exposure unit and a toner development unit is uniformly charged after the electrophotographic photosensitive member is uniformly charged and then fixed on the image support by a heating and fixing unit. an image forming apparatus characterized by using a fixing device for heating belt according to claim 1 or 2.

Images