JP5157135B2 - Endless belt, fixing device, and image forming apparatus - Google Patents

Description

  The present invention relates to an endless belt. The present invention also relates to a fixing device and an image forming apparatus using the endless belt.

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic system, for example, a photosensitive member (photosensitive drum) formed in a drum shape is uniformly charged, and the photosensitive drum is controlled based on image information. An electrostatic latent image is formed on the photosensitive drum by exposure with the exposed light. Then, the electrostatic latent image is converted into a visible image (toner image) with toner, and the toner image is primarily transferred from the photosensitive drum to the intermediate transfer belt, and then secondarily transferred from the intermediate transfer belt to the recording paper. The toner image is fixed on the recording paper by a fixing device.

As a conventional fixing device, for example, a rotatable heat fixing roll having a heating source, an endless belt which is in pressure contact with the heat fixing roll and is driven with the heat roll, and an inner end of the endless belt, the endless belt is arranged. A pressing member that presses the belt against the heating roll and forms a contact nip region between the endless belt and the heating fixing roll, and is disposed in a state of being fitted inside both end portions of the endless belt, And a belt guide member that rotatably guides the inner surface of the endless belt, and by passing the sheet through this nip portion, an unfixed toner image on the sheet is heated and pressed and fixed. In this type of fixing device (belt nip type), the endless belt is controlled in its walk by guide members at both ends. If the number of times the endless belt hits the belt regulating member disposed at both ends increases due to the long-term use of the endless belt, the end of the endless belt will wear due to sliding with the belt regulating member, and the end of the endless belt will crack. There is a possibility that the end portion breaks in the worst case.
The occurrence of such cracks and breaks at the end of the belt is not limited to the fixing device of the belt nip method, but is a common problem in a fixing system using an endless belt. Improvement of the control system in the belt drive system In addition, improvement is achieved by increasing the durability of the belt itself.

For example, as an improvement of the belt driving system, a contact portion of the belt regulating member with the edge surface of the belt member is configured to be elastically deformable (see, for example, Patent Document 1), and a belt. As an improvement by improving its own durability, a belt having a heat-resistant coating layer or a heat-resistant tape attached to the outer surface and / or inner surface of the peripheral edge of both ends of the belt (for example, patents) Reference 2), the thickness of both ends of the belt metal layer is larger than the thickness of the central portion (see, for example, Patent Document 3), and further, the belt outer peripheral layer has a rubber layer, and the rubber layer Have already been proposed (for example, see Patent Document 4).
JP 2006-0665250 A JP-A-5-345369 JP 2005-31474 A JP 2005-55469 A

However, the conventional technique has the following problems.
That is, the improvement in the belt drive system is not preferable because the cost is increased as compared with a simple butting type guide. Therefore, it is preferable to improve by improving the durability of the belt itself, and it is most effective to increase the film thickness of the belt, but the paper is peeled off due to the increase in cost and the decrease in flexibility of the belt. Defects will occur. If the thickness is increased while maintaining only the film thickness at the belt end, the manufacturing cost will increase. Furthermore, if a heat-resistant coating layer or heat-resistant tape is affixed to the end of the belt or a reinforcing rib such as silicone rubber is added, the wear resistance against repeated sliding with the guide and repeated fatigue durability are insufficient. Rotational sliding resistance with the belt guide provided in can not be stably maintained over a long period of time.

  The present invention does not require a complicated system, increases the strength of one or both ends of the endless belt with a thin and uniform film thickness, excavates the endless belt, wears or deforms the endless belt, or breaks the belt. It is an object of the present invention to provide a low-cost endless belt that can surely prevent the occurrence of cracks that lead to. Still another object of the present invention is to provide a highly durable electrophotographic fixing device and image forming apparatus using the endless belt.

The inventors of the present invention have conducted research on an endless belt and an electrophotographic fixing device in order to achieve the above object, and as a result, the present invention has been completed. That is, the present invention
<1> a belt main body having a base layer containing a heat-resistant resin, and a coating layer containing a thermoplastic resin on the base layer;
On one or both sides of an end portion of the belt body, a bent portion becomes bent 90 ° or more toward the outer side,
A joint that joins between the belt body and the bent portion, the joint formed by the thermoplastic resin;
It is an endless belt characterized by having .

<2> The endless belt according to < 1 > , wherein the joint includes a reinforcing member.

< 3 > a fixing member;
Base layer comprising a heat-resistant resin, and a belt body having a coating layer containing a thermoplastic resin on the base layer, the end portion of one or both sides of the belt body, toward the outer side 90 ° An endless belt having a bent portion that is bent as described above, and a bonded portion that joins between the belt main body and the bent portion, and is formed of the thermoplastic resin ,
A pressure member that is disposed inside the endless belt and that presses the endless belt against the fixing member to form a contact portion between the fixing member and the endless belt;
The fixing device is characterized by comprising:

< 4 > An image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming a latent image on the surface of the image carrier, and developing the latent image with toner to form a toner image. Developing means, transfer means for transferring the toner image to a recording medium, and fixing means for heat-fixing the toner image on the recording medium,
The fixing means is
A fixing member;
Base layer comprising a heat-resistant resin, and a belt body having a coating layer containing a thermoplastic resin on the base layer, the end portion of one or both sides of the belt body, toward the outer side 90 ° An endless belt having a bent portion that is bent as described above, and a bonded portion that joins between the belt main body and the bent portion, and is formed of the thermoplastic resin ,
A pressure member that is disposed inside the endless belt and that presses the endless belt against the fixing member to form a contact portion between the fixing member and the endless belt;
An image forming apparatus comprising a fixing device having the above.

According to the present invention, a complicated system is not required, the strength of one end or both ends of the endless belt having a thin and uniform film thickness is increased, and the endless belt is dug or worn and deformed at the end of the endless belt. It is possible to provide a low-cost endless belt that can surely prevent the occurrence of cracks that lead to belt breakage.
In addition, according to the present invention, it is possible to provide a highly durable electrophotographic fixing device and an image forming apparatus using the endless belt.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the endless belt of the present invention will be described, and then the fixing device of the present invention and the image forming apparatus of the present invention using the belt will be described.

<Endless belt>
The endless belt of the present invention is characterized in that one or both ends in the axial direction of the belt main body have a bent portion that is bent by 90 ° or more toward the outer side or the inner side of the belt main body.
However, the endless belt of the present invention includes a belt main body having a base layer containing a heat-resistant resin, and a coating layer containing a thermoplastic resin on the base layer, and one or both ends of the belt main body. A bent portion that is bent by 90 ° or more toward the outside, and a bonded portion that joins between the belt body and the bent portion, the bonded portion formed by the thermoplastic resin. The endless belt is used .

The endless belt of the present invention is manufactured by bending the end portion. The endless belt before processing is an endless belt in which at least one heat-resistant resin other than rubber is laminated. A single layer structure or a multilayer structure may be used. The shape, size, etc. are not particularly limited, but it is necessary that the expansion rate when the heat-resistant resin portion is bent is less than the tensile elongation at break of the resin.
FIG. 1 shows (A) the base layer 12 only before processing of the endless belt of the present invention, and (B) the base layer 12 formed with a coating layer 14 containing a thermoplastic resin. It is sectional drawing which shows an example. The endless belt of the present invention is formed by bending one or both ends of the endless belt in the state shown in FIG.

In the present invention, by subjecting the end of the belt body to bending, there is no direct contact between the cut-out surface of the end of the belt body and the sliding surface of the belt guide. The end of the endless belt is greatly reinforced by joining the main body to the main body) or by adding a reinforcing member, resulting in low-cost cracking that leads to wear deformation and belt breakage of the endless belt. Can be effectively prevented.
As an endless belt according to the present invention, the endless belt whose base layer is made of a heat-resistant resin has durability at the end of the endless belt even in a fixing system other than the fixing system in which the walk is controlled by belt guides at both ends. There is a sufficient effect for improvement. Furthermore, it is also effective for reinforcing the end of the intermediate transfer belt that similarly uses an endless belt made of a heat-resistant resin. According to the endless belt of the present invention, It is possible to provide a continuous and continuous reinforcing portion, and it is possible to prevent the occurrence of a failure due to a step or peeling at the joint portion of the reinforcing member or the meandering prevention guide member.

In the present invention, the bent portion is formed by bending the end portion of the belt main body, and the length of the belt main body to be bent is preferably 0.2 to 10 mm, and more preferably 0.5 to 5 mm.
Further, as described above, the bent portion is formed by bending the end portion of the belt main body by 90 ° or more toward the outside or the inside, and the angle is 120 to 180 ° when bent to the outside. Preferably, 150 to 180 ° is more preferable. Moreover, when bent inside, 160-180 degrees are preferable and 170-180 degrees are more preferable. Also, at a bending angle of less than 90 °, when bent outward, the cut-out surface of the end of the belt body and the surface of the belt guide member that regulates the lateral displacement of the belt guide are in direct contact with each other and the belt thrust direction (rotation) When the end of the belt body is pressed against the vertical surface of the belt guide member, an expanding force is applied to the end of the belt body, cracking occurs, and the belt It will lead to breakage. Even when the belt is bent inward, the cut-out surface of the end of the belt body and the vertical surface of the belt guide member are in direct contact with each other, and a force in the belt thrust direction (direction perpendicular to the rotational direction) is applied to the end of the belt body. When the part is pressed against the vertical surface of the belt guide member, a force is generated to shrink the end of the belt body inward, and it comes into strong contact with the sliding surface horizontal to the belt thrust direction of the belt guide, As a result of the increase in sliding resistance at the contact portion, rotation failure of the endless belt occurs. Furthermore, a crack that leads to breakage of the end of the belt main body occurs.
In the endless belt of the present invention, the bent portion may be provided only on one side, but is preferably provided on both sides from the viewpoint of more effectively achieving the effects of the present invention.

  The above-mentioned bending angle is the side where the end of the belt in the axial direction is bent with respect to the belt body when the cross section when the central axis of the belt is cut along the axial direction of the endless belt. Of the angle (obtuse angle) formed by the extension line of the inner wall surface of the belt body on the opposite side and the tangent line of the bent portion on the opposite side to the belt body side, the maximum angle within 180 ° say. When the extension line and the tangent line are parallel, the bending angle is 180 °. Specifically, for example, as shown in FIG. 10, when the bent portion 10 </ b> A is formed on a flat surface outside the belt body 10 (when the bent portion is formed by non-bending), the belt body The angle θ (obtuse angle) formed between the extension line of the inner plane (inner wall surface) 10 and the extension line of the plane (outer wall surface) of the bent portion 10A at the outer portion of the belt body 10 is the bending angle. . The bending angle can be easily confirmed by taking a photograph of a cross section of the endless belt, appropriately enlarging it, and analyzing it.

  Here, the bent portion can be more easily manufactured when the outer wall surface is a flat surface (one that is not bent), but may be a curved surface (may be bent). . Further, the bent portion may have a rounded shape (see, for example, FIG. 9) or a folded shape. In the case of a rounded shape or a folded shape, the bending angle is regarded as 180 °. FIG. 9 is a cross-sectional view showing an example of an endless belt having a bent portion with a rounded shape, where 10 indicates a belt body, 10A indicates a bent portion, and 16 indicates a joint portion.

  By the way, in the case of a rubber material, etc., it generally has an elastic deformation of about 100% to 500% or more, whereas the heat-resistant resin has an elastic deformation of several percent, and if it is pulled more than that, it will be plastically deformed. . Further, the tensile breaking elongation is usually about 10 to 30%, and even a high one is about 100% or less. For this reason, in the case of a rubber material, it is possible to easily bend without breakage of the end portion without special processing equipment, etc., whereas once it is plastically deformed with a heat resistant resin, Like rubber, it does not return to its original shape, but if it is folded in the same way as rubber, the end will crack, or the outer diameter of the edge will open greatly with respect to the root of the bending without cracking. Can not be made.

  That is, when bending the belt main body using the heat resistant resin, if the expansion rate of the end of the belt main body is expanded beyond the tensile breaking elongation of the heat resistant resin, the end is cracked. Even within the elongation at break, the outer diameter of the end portion of the belt main body is greatly opened with respect to the root of bending.

Therefore, when a heat resistant resin is used as the base layer in the belt main body of the present invention, as shown in FIG. 2, the expansion ratio of the outer diameter (φB) after processing is larger than the outer diameter (φA) before processing. Generation of cracks can be avoided by carrying out processing at a tensile breaking elongation of less than. Further, in order to prevent the outer diameter of the end portion of the belt main body from opening with respect to the bending base, it is preferable to perform the bending process with a certain expansion rate.
2 shows a state where one end of the endless belt 10X shown in FIG. 1A is bent outward by 90 °, and FIG. 2B shows a state where one end of the endless belt 10Y shown in FIG. The state bent outward is shown. In FIG. 2, reference numeral 10 </ b> A is a bent portion.

  In the endless belt of the present invention, examples of the method for bending the end portion of the belt main body include the following processing methods.

  An example of the processing method is shown in FIG. The belt main body 10 that is a workpiece is fixed to the core metal 20 on the non-processing side, and the processing side is inserted into a metal mold 22 that is slightly larger than the outer diameter of the belt main body. A convex R shape corresponding to the inner bending R is provided over the entire circumference. The mold 22 is movable from the machining end side to the opposite side with respect to the axial direction of the belt body. Further, in the direction opposite to the mold 22 (left side in FIG. 3), a mold 24 having a concave R shape with a curvature corresponding to the outer periphery of the bend R on the outer surface side of the belt main body is formed on the mold 20. It is provided so that it can advance and retreat in the axial direction.

A method of forming a bent portion in the belt body 10 in the above configuration will be described.
First, the front end portion of the belt main body 10 is slightly protruded from the front end portion of the mold 22, and then the mold 24 is pressed in this state to deform the front end portion of the belt main body 10. Next, the pressing of the mold 24 is released, the mold 22 is moved slightly to the non-processed side, and the mold 24 is pressed again to deform the tip of the belt body 10. Further, the end of the belt body 10 can be bent by repeatedly projecting the end of the belt body 10 and pressing the mold 24 in the same manner. When the end portion of the belt main body is bent inward, it is possible to provide a mold 22 inside the belt main body 10. In this case, however, the outer diameter of the mold 22 is slightly smaller than the inner diameter of the belt body.
In any case, it is also possible to fix the mold 22 and move the belt body.

  The metal mold 24 may be a spatula having a concave portion corresponding to the bending R, and the end of the belt main body can be deformed by rotating the outer periphery of the belt main body together with the protrusion of the belt main body. In addition, the die 24 can be formed of an elastomer mandrel at the tip, and the end of the belt body can be deformed by pressurizing the liquid in the mandrel and expanding the tip of the mandrel (basil processing).

  In addition, the mold 22 or the mold 24 is provided with various heating means, or separately provided with heating means by infrared rays or heated air blowing, and the heat-resistant resin material is heated to increase the tensile elongation at break. It is more preferable to perform the process.

  The material of the belt body can be appropriately selected from various known plastic materials, but among plastic materials, what is generally called engineering plastic is suitable, for example, fluorine resin, polyimide (PI ), Polyamideimide (PAI), Polybenzimidazole (PBI), Polyetheretherketone (PEEK), Polysulfone (PSU), Polyethersulfone (PES), Polyphenylenesulfide (PPS), Polyetherimide (PEI), Perfume Group polyester (liquid crystal polymer) and the like are preferable. Of these, thermosetting polyimides, thermoplastic polyimides, polyamide imides, polyether imides, fluororesins, and the like that are excellent in mechanical strength, heat resistance, wear resistance, chemical resistance, and the like are preferable. The thickness of the belt body is preferably in the range of 20 to 200 μm, and more preferably in the range of 50 to 100 μm.

  Further, it is possible to laminate a metal over the entire surface or a part of the belt body, and the metal material is not particularly limited, and various metals can be appropriately used. For example, SUS, nickel, copper, aluminum and the like are preferable. Can be used. The thickness of the metal is preferably in the range of 3 to 70 μm, and more preferably in the range of 5 to 40 μm. However, in consideration of flexibility as a belt, it is desirable that the thickness of the metal is equal to or less than the thickness of the belt body when the metal is also laminated at the bent portion.

  In addition to the metal or in addition to the metal layer, a rubber material can be laminated over the entire surface or a part of the belt body, and can be appropriately used from various rubber materials. For example, urethane rubber, ethylene / propylene Rubber (EPM), silicone rubber, fluororubber (FKM) and the like can be raised, and silicone rubber excellent in heat resistance and processability is particularly preferable. The thickness of the rubber material is preferably in the range of 30 to 500 μm, and more preferably in the range of 100 to 300 μm.

  When an endless belt is used as a fixing belt, a fluororesin is preferably laminated on the outermost layer as a surface release layer of the belt body. For example, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) ), Tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoroethylene-perfluoroethyl vinyl ether copolymer (EFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyethylene-tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoride ethylene (PCTFE), vinyl fluoride (PVF), and the like. From the surface of polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoroethylene-perfluoroethyl vinyl ether An (EFA) copolymer or a modified product thereof is preferably used. The thickness of the surface release layer is preferably in the range of 5 to 200 μm, and more preferably in the range of 10 to 100 μm.

  Various fillers can be appropriately added to each layer of the belt body in accordance with purposes such as conductivity, thermal conductivity, insulation, peelability, slidability, and reinforcement. As a filler, a lubricating filler having a layered structure (for example, molybdenum disulfide, hexagonal boron nitride, mica, graphite, molybdenum disulfide disulfide, talc), a conductive filler (for example, carbon black, graphite), Filler composed of heat-resistant resin (for example, filler in which the heat-resistant resin is selected from imide resin, amide resin, and wholly aromatic polyester resin: polyimide, liquid crystal polymer, aramid), and others (glass (Powder, aluminum silicate, carbon fiber, bronze, potassium titanate, titanium oxide, metal powder, barium sulfate, metal oxide, carbide, nitride, silicate compound) can be used.

  In the endless belt of the present invention, it is preferable to have a joint portion that joins between the belt main body and the bent portion. In this aspect, as shown in FIG. 4, the joint 16 is formed by filling the gap between the bent portion 12 </ b> A and the outer peripheral surface or inner peripheral surface of the belt body 12. In FIG. 4, (A) is an example having a bent portion on the outer side of the endless belt, and (B) is an example having a bent portion on the inner side. Is attached.

  As the filler forming the joint portion, various adhesives, various unvulcanized rubbers, various thermosetting resins, and various thermoplastic resins can be used. Moreover, what exhibits adhesiveness by heating or pressurization needs to be heated after pressurization in a gap and pressurized as necessary. In addition, a thermoplastic resin or the like can be heat-fusing (ultrasonic fusing) by applying ultrasonic vibration under pressure.

  Examples of the adhesive include condensation-curing or addition-curing silicone adhesives mainly composed of organopolysiloxane, and modified silicone-based adhesives mainly composed of polypropylene oxide (modified silicone) terminated with a methyldimethoxysilyl group. Agent, polyimide adhesive based on low molecular weight polymer of polyimide (PI) belonging to aromatic heterocyclic polymer, polybenzimidazole (PBI) based on polybenzimidazole belonging to aromatic heterocyclic polymer Imidasol adhesive, epoxy resin based epoxy resin, urethane resin adhesive, reactive hot melt adhesive, polyurethane resin hot melt adhesive, polyamide resin hot melt adhesive, polyolefin resin hot melt adhesive Agents, chloroprene rubber adhesives, etc. In terms of sex, silicone or modified silicone or polyimide-based adhesive is preferred.

Further, various fillers can be added to the filler for the purpose of ensuring durability and conductivity. As filler, a lubricious filler having a layered structure (for example, molybdenum disulfide, hexagonal boron nitride, mica, graphite, molybdenum disulfide, talc), conductive filler (for example, carbon black, graphite), heat resistance Fillers comprising resin (for example, fillers in which the heat resistant resin is selected from imide resins, amide resins, and wholly aromatic polyester resins: polyimide, liquid crystal polymer, aramid), and others (glass powder, Aluminum silicate, carbon fiber, bronze, potassium titanate, titanium oxide, metal powder, barium sulfate, metal oxide, carbide, nitride, silicate compound) and the like can be used. It is also possible to add a new surface layer after processing the joint.

  In the endless belt of the present invention, the belt main body may have a coating layer containing a thermoplastic resin on a base layer, and the joining portion may be formed of the thermoplastic resin. In this aspect, as shown in FIG. 5, the belt 14 is folded so that the cover layer 14 of the bent portion 12A and the cover layer 14 of the belt body 12 come into contact with each other. Alternatively, by applying ultrasonic vibration, the coating layers made of the thermoplastic resin are united, and the joint portion 16 is formed. 5A is an example having a bent portion on the outer side of the endless belt, and FIG. 5B is an example having a bent portion on the inner side, both of which are the same as those in FIGS. The same sign is attached.

  As the thermoplastic resin of the coating layer, various commercially available thermoplastic resins can be used, but considering heat resistance, various fluororesins, thermoplastic polyimide (PI), polyamideimide (PAI), polyetherimide ( PEI) is suitable. It is also possible to add a new surface layer after processing the joint.

  In any of the above embodiments, it is preferable that the joint portion includes a reinforcing member from the viewpoint of further improving the strength. In this aspect, as shown in FIG. 6, a filler is filled in a gap between the bent portion 12A and the outer peripheral surface or inner peripheral surface of the belt main body 12, and a reinforcing member 18 is further enclosed in the filler to join the joint portion. 16 is formed. In FIG. 6, (A) is an example having a bent portion on the outer side of the endless belt, and (B) is an example having a bent portion on the inner side. Is attached.

  As the reinforcing member, various resins, rubbers, metals and composite materials thereof can be used, and can be appropriately selected from commercially available products. It is also possible to add a new surface layer after processing the joint.

  In addition, after one side or both sides of the belt body composed of a single layer or multiple layers are bent toward the outside or the inside, a variety of heat resistant resins such as fluororesin, various metals, or various types are newly formed thereon. It is also possible to laminate a plurality of rubber materials to form an endless belt.

<Fixing device>
Next, the fixing device of the present invention using the endless belt of the present invention will be described.
FIG. 7 is a schematic cross-sectional view of the fixing device according to the embodiment of the present invention.
In the fixing device 30 shown in FIG. 7, 31 is a fixing roll, 32 is an endless belt, 33 is a recording medium, 34 is a heating source, 35 is a support, 36 is a pressing member, 36a is a pre-nip member, 36b is a peeling nip member, 37 is a sliding sheet member, 38 is a belt guide, 39 is a toner image, and 40 is a lubricant holding member. In the fixing device 30, the endless belt 32 is an endless belt to which the present invention described above is applied, and has the effects described above such as high durability.

  In the fixing device 30 shown in FIG. 7, an endless belt 32 is circumscribed on a driving type fixing roll 31, and an elastic body is mounted on a support 35 with respect to the endless belt 32 of the circumscribed portion, and a sliding sheet member 37. The pressing member 36 covered with is inscribed, and a nip portion is formed between the fixing roll 31 and the endless belt 32, and a lubricant is interposed on the sliding surface with respect to the endless belt 32. The lubricant supplied to the inner surface of 32 is rotated and supplied to the sliding surface side of the nip portion. Further, the fixing roll 31 and the endless belt 32 are heated to a predetermined temperature by the heating source 34 and rotate in the directions of the arrows, respectively. The toner image is fixed while the recording medium 33 passes through the nip portion. Further, the belt guide 38 is fixed to the support 35.

Hereinafter, members other than the endless belt used in the fixing device of the present embodiment will be described.
The fixing roll as the fixing member is not particularly limited in shape, structure, size, etc., and can be appropriately selected from those known per se according to the purpose. The heat-fixing roll generally includes a cylindrical core, an elastic layer formed on the surface thereof, and a release layer formed on the surface of the elastic layer. Such a fixing roll can be manufactured by a known manufacturing method. Generally, a mold for forming an elastic layer is disposed around a cylindrical core, and liquid rubber is formed between the mold and the cylindrical shape. After being poured into the gap between the cores, vulcanized and hardened, and a resin sleeve such as PFA on the surface can be used.

  The material of the cylindrical core is not particularly limited as long as the material has excellent mechanical strength and good heat transfer properties. For example, metals such as aluminum, SUS, iron and copper, alloys, ceramics, FRM, etc. Is mentioned.

  The material of the elastic layer can be appropriately selected from known materials for the elastic layer, and examples thereof include silicone rubber and fluorine rubber. In the present invention, among these materials, silicone rubber is preferable because it has a small surface tension and is excellent in elasticity. Examples of the silicone rubber include RTV silicone rubber and HTV silicone rubber. Specifically, polydimethyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ), methyl phenyl silicone rubber (PMQ), fluoro Examples include silicone rubber (FVMQ).

  The thickness of the elastic layer is preferably 3 mm or less, and more preferably in the range of 0.5 to 1.5 mm.

  A release layer is formed on the surface of the elastic layer. When the release layer is formed, the offset of the toner image can be suitably prevented. The material of the release layer is not particularly limited as long as it exhibits an appropriate release property with respect to the toner image, and examples thereof include fluorine rubber, silicone rubber, and fluorine resin. Among these materials, a fluororesin is preferable.

  Examples of the fluororesin include, for example, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoroethylene-perfluoroethyl vinyl ether copolymer ( EFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyethylene-tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polychloroethylene trifluoride (PCTFE), Fluorine resin such as vinyl fluoride (PVF) can be used.

  Polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoro, especially in terms of heat resistance and mechanical properties An ethylene-perfluoroethyl vinyl ether (EFA) copolymer is preferably used.

  As a thickness of a mold release layer, it is 10-100 micrometers normally, Preferably it is 20-30 micrometers. There is no restriction | limiting in particular as a method of forming the said mold release layer in the surface of the said core, For example, the method of coat | covering the tube formed by extrusion molding is mentioned.

  As the heat source, for example, a halogen lamp is used, and there is no particular limitation as long as it has a shape and structure that can be accommodated inside the core, and can be appropriately selected according to the purpose. The surface temperature of the heat fixing roll heated by the halogen lamp is measured by a temperature sensitive element provided on the heat fixing roll, and the temperature is controlled to be constant by the control means. There is no restriction | limiting in particular as a temperature sensing element, For example, a thermistor, a temperature sensor, etc. are mentioned. The pressing (pressurizing) member may have a resistance heating mechanism.

  As a pressing pad, an elastic body is mounted on a support, and is placed inside the endless belt, presses the heat fixing roll via the endless belt, and an unfixed toner image is formed between the endless belt and the heat fixing roll. There is no particular limitation as long as it has a function capable of forming a nip portion through which a recording sheet that holds the sheet can pass, and can be appropriately selected from known ones according to the purpose. From the viewpoint of prevention, it is preferable to use a material having heat resistance.

  As the material of the elastic body, heat-resistant elastomers such as silicone rubber and fluororubber are suitable, and among these materials, silicone rubber is preferable in terms of excellent elasticity. Examples of the silicone rubber include RTV silicone rubber and HTV silicone rubber. Specifically, polydimethyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ), methyl phenyl silicone rubber (PMQ), fluoro Examples include silicone rubber (FVMQ). From the viewpoint of hardness, silicone rubber having a JIS-A hardness of 10 to 40 ° is preferably used.

  There is no restriction | limiting in particular about the shape of a elastic body, a structure, a magnitude | size, etc., According to the objective, it can select suitably. The pressing pad may have a structure composed of a single member or a structure composed of a plurality of members having different functions. When silicone oil is used as the sliding oil, polydimethyl silicone rubber or methyl vinyl silicone rubber is easily swollen by silicone oil, and it is necessary to coat the surface of the elastic body with a fluororesin or the like.

  Further, as a sliding member interposed between the pressing member and the endless belt, at least the contact surface side with the endless belt is formed of a fluororesin having an uneven shape on the surface. This uneven shape holds the lubricant.

  Silicone oil is preferable as the lubricant, and dimethyl silicone oil, dimethyl silicone oil with addition of organometallic salt, dimethyl silicone oil with addition of hindered amine, dimethyl silicone oil with addition of organometallic salt and hindered amine, methylphenyl silicone oil, amino-modified silicone oil are preferred as the silicone oil. It is also possible to use amino-modified silicone oil with addition of organometallic salt, amino-modified silicone oil with addition of hindered amine, carboxy-modified silicone oil, silanol-modified silicone oil, sulfonic acid-modified silicone oil, etc. preferable. In addition, when superior performance due to heat resistance is required, it is also preferable to use methylphenyl silicone oil or fluorine oil (perfluoropolyether oil, modified perfluoropolyether oil) or the like. In addition, in order to improve heat resistance, it is also possible to add a trace amount antioxidant in silicone oil. In addition, synthetic lubricating oil grease in which a solid substance and a liquid are mixed, for example, silicone grease, fluorine grease, or the like, or a combination thereof can also be used.

<Image forming apparatus>
Next, the image forming apparatus of the present invention provided with the fixing device of the present invention will be described.
FIG. 8 is a schematic configuration diagram illustrating an image forming apparatus to which the exemplary embodiment is applied. The image forming apparatus shown in FIG. 8 is an intermediate transfer type image forming apparatus generally called a tandem type, and a plurality of image forming units Y, M, C, K, a primary transfer portion 40 for sequentially transferring (primary transfer) each color component toner image formed by each image forming unit Y, M, C, K to the intermediate transfer belt 45, and a superimposition transferred on the intermediate transfer belt 45 A secondary transfer unit 50 that batch-transfers (secondary transfer) toner images to a sheet P that is a recording material (recording sheet), and a fixing device 30 that fixes the secondary-transferred image on the sheet P are provided. The fixing device 30 is a fixing device to which the above-described present invention is applied, and the fixing device has an endless belt to which the above-described present invention is applied. Therefore, the endless belt has the above-described effects such as high durability.
Moreover, it has the control part 70 which controls operation | movement of each apparatus (each part).

  In the present embodiment, each of the image forming units Y, M, C, and K has a charger 42 and a photosensitive drum 41 that are charged around the photosensitive drum 41 that rotates in the direction of arrow A. A laser exposure device 43 on which an electrostatic latent image is written (exposure beam is indicated by a symbol Bm in the figure), each color component toner is accommodated, and the electrostatic latent image on the photosensitive drum 41 is visualized with toner. A developing unit 44, a primary transfer roll 46 for transferring each color component toner image formed on the photosensitive drum 41 to an intermediate transfer belt 45 by a primary transfer unit 40, and a drum from which residual toner on the photosensitive drum 41 is removed. Electrophotographic devices such as a cleaner 47 are sequentially arranged. These image forming units Y, M, C, and K are arranged in a substantially straight line from the upstream side of the intermediate transfer belt 45 in the order of yellow (Y), magenta (M), cyan (C), and black (K). Has been.

The intermediate transfer belt 45, which is an intermediate transfer body, is composed of a film-like endless belt in which an appropriate amount of an antistatic agent such as carbon black is contained in a resin such as polyimide or polyamide. And the volume resistivity is formed so that it may become 10 < ⁶ > -10 < ¹⁴ > (omega | ohm) cm, The thickness is comprised by about 0.1 mm, for example. The intermediate transfer belt 45 is circulated (rotated) at a predetermined speed in the direction B shown in FIG. 8 by various rolls. As these various rolls, a drive roll 61 that is driven by a motor (not shown) having excellent constant speed and rotates the intermediate transfer belt 45, and an intermediate that extends substantially linearly along the arrangement direction of the photosensitive drums 41. A support roll 62 that supports the transfer belt 45, a tension roll 63 that functions as a correction roll that applies a constant tension to the intermediate transfer belt 45 and prevents meandering of the intermediate transfer belt 45, and a backup provided in the secondary transfer section 50. A cleaning backup roll 64 provided in a cleaning unit that scrapes off residual toner on the roll 55 and the intermediate transfer belt 45 is provided.

The primary transfer unit 40 includes a primary transfer roll 46 that is disposed to face the photosensitive drum 41 with the intermediate transfer belt 45 interposed therebetween. The primary transfer roll 46 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is a cylindrical bar made of metal such as iron or SUS. The sponge layer is a sponge-like cylindrical roll formed of a blend rubber of NBR, SBR and EPDM containing a conductive agent such as carbon black and having a volume resistivity of 10 ^7.5 to 10 ^8.5 Ωcm. The primary transfer roll 46 is disposed in pressure contact with the photosensitive drum 41 with the intermediate transfer belt interposed therebetween. Further, the primary transfer roll 46 has a voltage (primary polarity) opposite to the toner charging polarity (negative polarity; the same applies hereinafter). Transfer bias) is applied. As a result, the toner images on the respective photosensitive drums 41 are sequentially electrostatically attracted to the intermediate transfer belt 45, and the superimposed toner images are formed on the intermediate transfer belt 45.

The secondary transfer unit 50 includes a secondary transfer roll 52 and a backup roll 55 arranged on the toner image carrying surface side of the intermediate transfer belt 45. The backup roll 55 is composed of a tube of EPDM and NBR blend rubber with carbon dispersed on the surface, and EPDM rubber inside. And it is formed so that the surface resistivity may be 10 ⁷ to 10 ¹⁰ Ω / □, and the hardness is set to, for example, 70 ° (Asker C: manufactured by Kobunshi Keiki Co., Ltd.). The backup roll 55 is disposed on the back side of the intermediate transfer belt 45 to form a counter electrode of the secondary transfer roll 52, and a metal power supply roll 56 to which a secondary transfer bias is stably applied is disposed in contact with the backup roll 55. ing.

On the other hand, the secondary transfer roll 52 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is a cylindrical bar made of metal such as iron or SUS. The sponge layer is a sponge-like cylindrical roll formed of a blend rubber of NBR, SBR and EPDM containing a conductive agent such as carbon black and having a volume resistivity of 10 ^7.5 to 10 ^8.5 Ωcm. The secondary transfer roll 52 is placed in pressure contact with the backup roll 55 with the intermediate transfer belt 45 interposed therebetween. Further, the secondary transfer roll 52 is grounded, and a secondary transfer bias is formed between the secondary transfer roll 52 and the backup roll 55. The toner image is secondarily transferred onto the paper P conveyed to the transfer unit 50.

  Further, on the downstream side of the secondary transfer portion 50 of the intermediate transfer belt 45, an intermediate transfer belt that removes residual toner and paper dust on the intermediate transfer belt 45 after the secondary transfer and cleans the surface of the intermediate transfer belt 45. A cleaner 65 is provided so as to be able to contact and separate. On the other hand, on the upstream side of the yellow image forming unit Y, there is a reference sensor (home position sensor) 72 that generates a reference signal as a reference for taking the image forming timing in each of the image forming units Y, M, C, and K. It is arranged. Further, an image density sensor 73 for adjusting image quality is disposed on the downstream side of the black image forming unit K. The reference sensor 72 recognizes a predetermined mark provided on the back side of the intermediate transfer belt 45 and generates a reference signal. Each image forming unit is instructed by an instruction from the control unit 70 based on the recognition of the reference signal. Y, M, C, and K are configured to start image formation.

  Further, in the image forming apparatus of the present embodiment, as a paper transport system, a paper tray 80 that stores paper P, a pickup roll 81 that picks up and transports the paper P accumulated in the paper tray 80 at a predetermined timing, and a pickup After the transfer roll 82 that transports the paper P fed by the roll 81, the transport chute 83 that feeds the paper P transported by the transport roll 82 to the secondary transfer unit 50, and the secondary transfer roll 52 after the secondary transfer. A conveyance belt 85 that conveys the conveyed paper P to the fixing device 30 and a fixing entrance guide 86 that guides the paper P to the fixing device 30 are provided.

  Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described. In the image forming apparatus as shown in FIG. 8, image data output from an unillustrated image reading device (IIT), unillustrated personal computer (PC) or the like is subjected to predetermined image processing by an unillustrated image processing device (IPS). Is applied, the image forming operation is executed by the image forming units Y, M, C, and K. In IPS, the input reflectance data is subjected to predetermined image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, moving editing, and other various image editing. Is done. The image data subjected to the image processing is converted into color material gradation data of four colors Y, M, C, and K, and is output to the laser exposure device.

  The laser exposure unit 43 irradiates the photosensitive drum 41 of each of the image forming units Y, M, C, and K with, for example, an exposure beam Bm emitted from a semiconductor laser in accordance with the input color material gradation data. Yes. In each of the photosensitive drums 41 of the image forming units Y, M, C, and K, the surface is charged by the charger 42, and then the surface is scanned and exposed by the laser exposure unit 43 to form an electrostatic latent image. The formed electrostatic latent image is developed as a toner image of each color of Y, M, C, and K in each of the image forming units Y, M, C, and K.

  The toner images formed on the photoconductive drums 41 of the image forming units Y, M, C, and K are transferred onto the intermediate transfer belt 45 by the primary transfer unit 40 where the photoconductive drums 41 and the intermediate transfer belt 45 abut. Is transcribed. More specifically, in the primary transfer unit 40, a voltage (primary transfer bias) having a polarity opposite to the charging polarity (minus polarity) of the toner is applied to the base material of the intermediate transfer belt 45 by the primary transfer roll 46. Primary transfer is performed by sequentially superimposing images on the surface of the intermediate transfer belt 45.

  After the toner images are sequentially primary transferred onto the surface of the intermediate transfer belt 45, the intermediate transfer belt 45 moves and the toner image is conveyed to the secondary transfer unit 50. When the toner image is transported to the secondary transfer unit 50, in the paper transport system, the pick-up roll 81 rotates in accordance with the timing at which the toner image is transported to the secondary transfer unit 50, and the paper of a predetermined size is transferred from the paper tray 80. P is supplied. The paper P supplied by the pickup roll 81 is transported by the transport roll 82, and reaches the secondary transfer unit 50 through the transport chute 83. Before reaching the secondary transfer unit 50, the paper P is temporarily stopped, and a registration roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 45 carrying the toner image, whereby the paper P And the position of the toner image are aligned.

  In the secondary transfer unit 50, the secondary transfer roll 52 is pressed against the backup roll 55 via the intermediate transfer belt 45. At this time, the sheet P conveyed at the same timing is sandwiched between the intermediate transfer belt 45 and the secondary transfer roll 22. At this time, when a voltage (secondary transfer bias) having the same polarity as the toner charging polarity (negative polarity) is applied from the power supply roll 56, a transfer electric field is formed between the secondary transfer roll 52 and the backup roll 55. Is done. The unfixed toner image carried on the intermediate transfer belt 45 is electrostatically transferred collectively onto the paper P by the secondary transfer unit 50 pressed by the secondary transfer roll 52 and the backup roll 55. The

Thereafter, the sheet P on which the toner image has been electrostatically transferred is transported as it is while being peeled off from the intermediate transfer belt 45 by the secondary transfer roll 52, and transported downstream of the secondary transfer roll 52 in the sheet transport direction. It is conveyed to the belt 85. The conveyance belt 85 conveys the paper P to the fixing device 30 in accordance with the optimum conveyance speed in the fixing device 30. The unfixed toner image on the paper P conveyed to the fixing device 30 is fixed on the paper P by being subjected to a fixing process by heat and pressure by the fixing device 30. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge placement unit provided in a discharge unit of the image forming apparatus.
On the other hand, after the transfer to the paper P is completed, the residual toner remaining on the intermediate transfer belt 45 is conveyed to the cleaning unit as the intermediate transfer belt 45 rotates, and the cleaning backup roll 64 and the intermediate transfer belt cleaner 65 are transferred. Is removed from the intermediate transfer belt 45.

  Although the embodiment of the present invention has been described above, the present invention is not construed as being limited to the above-described embodiment, and it is needless to say that the present invention can be realized within a range that satisfies the requirements of the present invention.

  Hereinafter, an endless belt to which the present invention is applied and a conventional endless belt that is not subjected to additional processing as a comparative example will be manufactured, and evaluation results when attached to a fixing device and an image forming apparatus will be specifically described. However, the present invention is not limited to the following examples.

( Reference Example 1)
First, an N-methylpyrrolidone solution of a polyimide (PI) resin precursor (trade name: U varnish, Ube Industries ( Co., Ltd.) was applied by a flow coating (spiral winding application) method and dried while rotating. Next, a fluororesin (PFA) dispersion solution (trade name: 710CL, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was coated by spray coating, and then the coating film was baked at 380 ° C. Next, it is removed from the core surface, and both ends are cut to form a coating layer having a thickness of 20 μm containing PFA as a thermoplastic resin on the outer periphery of the PI resin (heat resistant resin) having a thickness of 50 μm. In addition, a belt body having a total length of 346 mm was obtained. Next, both end portions of the belt main body were bent outward by 3 mm by the method shown in FIG. 3 to obtain an endless belt having a total length of 340 mm.
At this time, the radius of curvature of the tip of the mold 24 shown in FIG. 3 was 0.3 mm, and the outer diameter expansion rate by bending was about 3.5%. In addition, a PI resin-only belt having the same film thickness produced at the same time was tested with a tensile tester (1605N manufactured by Aiko Engineering Co., Ltd.) in accordance with JIS K7113 (1995), using a No. 4 type test piece at a test speed of 10 mm / min. As a result, the tensile modulus was 5700 MPa, the tensile strength at break was 420 MPa, and the tensile elongation at break was 18%. The tensile elongation at break was calculated by comparing the original length of the specimen with the length at the time of tensile fracture.

( Reference Example 2)
First, an N-methylpyrrolidone solution of a PI resin precursor (trade name: U varnish, manufactured by Ube Industries, Ltd.) on the surface of an aluminum cylindrical mold having an outer diameter of 30 mm subjected to blast treatment on the surface and then on the core surface ) Was applied by a flow coating (spiral winding application) method and dried while rotating. Next, the PI resin-coated mold other than the central portion of 340 mm is masked, and further a fluororesin (PFA) dispersion (trade name: 710CL, manufactured by Mitsui / DuPont Fluorochemical Co., Ltd.) is coated by spray coating. The coating was baked. Next, by removing from the surface of the core and further cutting both ends, a coating layer having a thickness of 20 μm containing PFA as a thermoplastic resin is formed on the outer periphery of the PI resin (heat-resistant resin) having a thickness of 50 μm with a total length of 346 mm. A belt main body formed at a central portion of 334 mm was obtained. Next, with the method shown in FIG. 3, the both ends of the belt main body were bent outward by 3 mm while blowing warm air at 200 ° C. to obtain an endless belt having a total length of 340 mm. At this time, the radius of curvature of the tip of the mold 24 shown in FIG. 3 was 0.4 mm, and the outer diameter expansion rate by bending was about 4.9%. In addition, a PI resin-only belt having the same film thickness produced at the same time was tested with a tensile tester (1605N manufactured by Aiko Engineering Co., Ltd.) in accordance with JIS K7113 (1995), using a No. 4 type test piece at a test speed of 10 mm / min. As a result, the tensile modulus was 5700 MPa, the tensile strength at break was 420 MPa, and the tensile elongation at break was 18%. The tensile elongation at break was calculated by comparing the original length of the specimen with the length at the time of tensile fracture.
Furthermore, after liquid silicone rubber (LSR) made of Shin-Etsu silicone rubber was injected as an adhesive into the gap between the bent portions, it was cured at 200 ° C. to bond the bent portions.

(Example 3)
First, an N-methylpyrrolidone solution of a PI resin precursor (trade name: U varnish, manufactured by Ube Industries, Ltd.) on the surface of an aluminum cylindrical mold having an outer diameter of 30 mm subjected to blast treatment on the surface and then on the core surface ) Was applied by a flow coating (spiral winding application) method and dried while rotating. Next, a fluororesin (PFA) dispersion solution (trade name: 710CL, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was coated by spray coating, and the coating film was baked at 380 ° C. Next, by removing from the surface of the core and further cutting both ends, a coating layer having a thickness of 20 μm containing PFA as a thermoplastic resin was formed on the outer periphery of the PI resin (heat resistant resin) having a thickness of 50 μm. A belt body having a total length of 346 mm was obtained. Next, both end portions of the belt main body were bent outward by 3 mm by the method shown in FIG. 3 to obtain an endless belt having a total length of 340 mm. At this time, the radius of curvature of the tip of the mold 24 shown in FIG. 3 was 0.25 mm, and the outer diameter expansion rate by bending was about 2.9%. At the same time, a belt made only of PI resin having the same film thickness was stretched by a tester (1605N manufactured by Aiko Engineering Co., Ltd.) in accordance with JIS K7113 (1995), and a test speed was 10 mm / min using No. 4 type test piece. As a result, the tensile modulus was 5700 MPa, the tensile strength at break was 420 MPa, and the tensile elongation at break was 18%. The tensile elongation at break was calculated by comparing the original length of the specimen with the length at the time of tensile fracture.
Further, both ends were heated to 350 ° C. to remelt the PFA, and the folded portions were bonded by applying pressure from the inside and outside of the folded portion.

Example 4
First, an N-methylpyrrolidone solution of a PI resin precursor (trade name: U varnish, manufactured by Ube Industries, Ltd.) on the surface of an aluminum cylindrical mold having an outer diameter of 30 mm subjected to blast treatment on the surface and then on the core surface ) Was applied by a flow coating (spiral winding application) method and dried while rotating. Next, a fluororesin (PFA) dispersion solution (trade name: 710CL, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was coated by spray coating, and then the coating film was baked at 380 ° C. Next, by removing from the core surface and further cutting both ends, a coating layer with a thickness of 20 μm containing PFA as a thermoplastic resin was formed on the outer periphery of the PI resin with a thickness of 50 μm. A belt body was obtained. Next, both end portions of the belt main body were bent outward by 3 mm by the method shown in FIG. 3 to obtain an endless belt having a total length of 340 mm. At this time, the radius of curvature of the tip of the mold 24 shown in FIG. 3 was 0.4 mm, and the outer diameter expansion rate by bending was about 4.9%. In addition, a PI resin-only belt of the same film thickness produced at the same time was tested with a tensile tester (1605N manufactured by Aiko Engineering Co., Ltd.) in accordance with JIS K7113 (1995), using a No. 4 type test piece at a test speed of 10 mm / min. As a result, the tensile modulus was 5700 MPa, the tensile strength at break was 420 MPa, and the tensile elongation at break was 18%. The tensile elongation at break was calculated by comparing the original length of the specimen with the length at the time of tensile fracture.
A stainless steel ring with a thickness of 15 μm, a width of 1.5 mm, and an outer diameter of 30 mm is inserted into the bent portion gap, and both ends are heated to 350 ° C. to remelt the PFA. The bent part was bonded by pressing.

( Reference Example 5)
First, an N-methylpyrrolidone solution of a PI resin precursor (trade name: U varnish, manufactured by Ube Industries, Ltd.) on the surface of an aluminum cylindrical mold having an outer diameter of 30 mm subjected to blast treatment on the surface and then on the core surface ) Was applied by a flow coating (spiral winding application) method and dried while rotating. Next, a fluororesin (PFA) dispersion solution (trade name: 710CL, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was coated by spray coating, and then the coating film was baked at 380 ° C. Next, it was removed from the surface of the core, and both ends were cut to form a coating layer with a thickness of 20 μm containing PFA as a thermoplastic resin on the outer periphery of the PI resin with a thickness of 50 μm. A belt body of 6 mm was obtained. Next, both ends of the belt main body were bent 90 ° outward by 0.8 mm by the method shown in FIG. 3 to obtain an endless belt having a total length of 340 mm. At this time, the radius of curvature of the tip of the mold 24 shown in FIG. 3 was 0 mm (planar), and the outer diameter expansion rate by bending was about 5%. In addition, a PI resin-only belt of the same film thickness produced at the same time was tested with a tensile tester (1605N manufactured by Aiko Engineering Co., Ltd.) in accordance with JIS K7113 (1995), using a No. 4 type test piece at a test speed of 10 mm / min. As a result, the tensile modulus was 5700 MPa, the tensile strength at break was 420 MPa, and the tensile elongation at break was 18%. The tensile elongation at break was calculated by comparing the original length of the specimen with the length at the time of tensile fracture.

( Reference Example 6)
First, an N-methylpyrrolidone solution of a PI resin precursor (trade name: U varnish, manufactured by Ube Industries, Ltd.) on the surface of an aluminum cylindrical mold having an outer diameter of 30 mm subjected to blast treatment on the surface and then on the core surface ) Was applied by a flow coating (spiral winding application) method and dried while rotating. Next, a fluororesin (PFA) dispersion solution (trade name: 710CL, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was coated by spray coating, and then the coating film was baked at 380 ° C. Next, the belt main body having a total length of 344 mm, which is removed from the core surface, further cut at both ends, and a coating layer having a thickness of 20 μm containing PFA as a thermoplastic resin is formed on the outer periphery of the PI resin having a thickness of 50 μm. Got. Next, in the method as shown in FIG. 3, the mold 22 is provided inside the endless belt 10 using a piece slightly smaller than the inner diameter of the endless belt, and both end portions of the belt body are bent inward and outward by 2 mm. And an endless belt having a total length of 340 mm. At this time, the radius of curvature of the tip of the mold 24 shown in FIG. 3 was 0.3 mm, and the protruding portion had a shape opposite to that when bent outward.
However, when it is folded inward, the outer diameter expansion rate will be negative, and if the endless belt is removed from the mold after folding, a hook-shaped deformation will occur at the folded part, which is about the same as the inner diameter of the belt. The heated cored bar was inserted and the folded portion was expanded to obtain a smooth folded portion. In addition, a PI resin-only belt of the same film thickness produced at the same time was tested with a tensile tester (1605N manufactured by Aiko Engineering Co., Ltd.) in accordance with JIS K7113 (1995), using a No. 4 type test piece at a test speed of 10 mm / min. As a result, the tensile modulus was 5700 MPa, the tensile strength at break was 420 MPa, and the tensile elongation at break was 18%. The tensile elongation at break was calculated by comparing the original length of the specimen with the length at the time of tensile fracture.

(Comparative Example 1)
First, an N-methylpyrrolidone solution of a PI resin precursor (trade name: U varnish, manufactured by Ube Industries, Ltd.) on the surface of an aluminum cylindrical mold having an outer diameter of 30 mm subjected to blast treatment on the surface and then on the core surface After coating with a flow coating method (spiral winding coating method) and rotating the coating, a fluororesin (PFA) dispersion (trade name: 710CL, manufactured by Mitsui / DuPont Fluorochemical Co., Ltd.) was applied by spray coating. The coating film was baked at 380 ° C. Next, the coating was removed from the core surface, both ends were cut, and a coating layer having a thickness of 20 μm containing PFA as a thermoplastic resin was formed on the outer periphery of the PI resin having a thickness of 50 μm. A formed belt body having a total length of 340 mm was obtained, and this belt body was not subjected to end bending, and the end of the belt body remained as a cut surface. The bell and the body obtained in this way were used as endless belts, and a belt made of only the same thickness PI resin was manufactured at the same time using a tensile tester (1605N manufactured by Aiko Engineering Co., Ltd.) in accordance with JIS K7113 (1995). As a result of measuring the test speed at 10 mm / min using a test specimen, the tensile modulus was 5700 MPa, the tensile breaking strength was 420 MPa, and the tensile breaking elongation was 18%. It calculated by comparing with the length at the time of a tensile fracture.

Evaluation results when the endless belts produced in Reference Examples 1-2, Examples 3-4, and Reference Examples 5-6 and the endless belt of Comparative Example 1 are attached to a fixing device and the fixing device is attached to an image forming apparatus are shown. explain.

The evaluation was performed using the fixing device shown in FIG. 7, and after attaching the endless belts prepared in Reference Examples 1-2, Examples 3-4, Reference Examples 5-6 , and Comparative Example 1 to the fixing device, The fixing device was attached to the image forming apparatus of FIG. Next, image printing is performed, and the fixing device is taken out from the image forming apparatus and printed on the end of the belt every 25,000, 50,000, 100,000, 150,000, and 200,000 prints. We confirmed about the damage situation.

  The fixing roll is a PFA tube having a thickness of 0.5 mm and a pipe made of a carbon steel pipe having an outer diameter of 25 mm and a silicone rubber (LSR manufactured by Shin-Etsu Chemical Co., Ltd.) having a thickness of 0.6 mm and an outermost surface layer having a thickness of 30 μm. (Mitsui / DuPont Fluoro Chemical Co., Ltd., 950HP-Plus was extruded and the inner surface was treated with an excimer laser) was injection-molded so as to be integrally coated.

  In the normal evaluation, a lubricant such as amine-modified silicone oil is added to the lubricant holding member 40. However, as an acceleration condition for confirming the durability of the endless belt end, the endless belt 32 is not added without adding lubricating oil. Attached to the fixing device.

As a result of the evaluation, a small crack was observed in the bent portion at the end of 200,000 sheets in Reference Example 5, but in each of Reference Examples 1-2, Examples 3-4, and Reference Example 6 , 200,000 sheets were used. It was possible to print without any problems up to printing. On the other hand, in Comparative Example 1, the end of the endless belt started to crack at 25,000 sheets, and the end of the endless belt broke before reaching 50,000 sheets, making printing impossible. Oops.

It is sectional drawing which shows the layer structure ((A) one layer, (B) two layers) of the belt which concerns on the processing of the endless belt of this invention. It is sectional drawing which shows the example of an endless belt of this invention ((A) The thing of the angle of 90 degrees of a bending part, (B) The thing of the angle of 180 degrees of a bending part). It is sectional drawing which shows an example of the bending method for producing the endless belt of this invention. It is sectional drawing which shows one Embodiment of the endless belt of this invention. It is sectional drawing which shows one Embodiment of the endless belt of this invention. It is sectional drawing which shows one Embodiment of the endless belt of this invention. 1 is a schematic configuration diagram illustrating an embodiment of a fixing device of the present invention. 1 is a schematic configuration diagram of an example of an image forming apparatus of the present invention. It is sectional drawing which shows the example (an example of the endless belt which has the bending part of the round shape) of the endless belt of this invention. It is sectional drawing for demonstrating a bending angle.

Explanation of symbols

10X, Y Endless belt 10 Belt body 10A Bending part 12 Base layer (belt body)
12A Bending portion 14 Covering layer 16 Joining portion 18 Reinforcing member 30 Fixing device 31 Fixing roll 32 Endless belt

Claims (4)

A belt main body having a base layer containing a heat-resistant resin, and a coating layer containing a thermoplastic resin on the base layer;
On one or both sides of an end portion of the belt body, a bent portion becomes bent 90 ° or more toward the outer side,
A joint that joins between the belt body and the bent portion, the joint formed by the thermoplastic resin;
An endless belt characterized by comprising: The endless belt according to claim 1 , wherein the joint includes a reinforcing member. A fixing member;
Base layer comprising a heat-resistant resin, and a belt body having a coating layer containing a thermoplastic resin on the base layer, the end portion of one or both sides of the belt body, toward the outer side 90 ° An endless belt having a bent portion that is bent as described above, and a bonded portion that joins between the belt main body and the bent portion, and is formed of the thermoplastic resin ,
A pressure member that is disposed inside the endless belt and that presses the endless belt against the fixing member to form a contact portion between the fixing member and the endless belt;
A fixing device. An image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming a latent image on the surface of the image carrier, and a developing unit for developing the latent image with toner to form a toner image And a transfer means for transferring the toner image to a recording medium, and a fixing means for heating and fixing the toner image to the recording medium,
The fixing means is
A fixing member;
Base layer comprising a heat-resistant resin, and a belt body having a coating layer containing a thermoplastic resin on the base layer, the end portion of one or both sides of the belt body, toward the outer side 90 ° An endless belt having a bent portion that is bent as described above, and a bonded portion that joins between the belt main body and the bent portion, and is formed of the thermoplastic resin ,
A pressure member that is disposed inside the endless belt and that presses the endless belt against the fixing member to form a contact portion between the fixing member and the endless belt;
An image forming apparatus comprising: a fixing device including:

Images