JP6488801B2 - Tubular body, fixing device and image forming apparatus - Google Patents

Description

  The present invention relates to a tubular body, a fixing device, and an image forming apparatus.

  In an image forming apparatus using powdery toner, a toner image is formed by selectively transferring toner to a latent image formed on an image holding member due to a difference in electrostatic potential. For example, after the toner image is electrostatically directly transferred onto the recording medium, or after the primary transfer to the intermediate transfer member and the secondary transfer onto the recording medium, the recording medium is placed between the heating member and the pressure member. Then, the toner image is heated and pressurized to be fixed on the recording medium.

  As a fixing device for fixing the toner image on the recording medium in this manner, the fixing device includes a fixing roll having a heating element such as a halogen lamp inside a cylindrical cored bar, and a pressure roll pressed against the fixing roll. Things are widely known. In this fixing device, when a recording medium holding an unfixed toner image is fed into a nip portion where the fixing roll and the pressure roll are pressed against each other, and passes between the fixing roll and the pressure roll that are rotationally driven. The toner image is heated and pressurized.

  In addition, a fixing device using an endless fixing belt as a fixing member instead of the fixing roll has been proposed. The fixing belt includes a type stretched by a plurality of support rolls, and a type having a pressing support inside and being driven to rotate by being pressed against the pressure roll in a non-tensioned state. The fixing belt uses a thin heat-resistant resin or the like as a base material and has a smaller heat capacity than a roll-shaped member, so that warm-up is performed in a short time. Furthermore, the shape of the nip portion can be freely formed by using the fixing belt.

  As a fixing roll or a pressure roll used in such a fixing device, for example, in Patent Document 1, a foamed elastic layer disposed on an outer peripheral surface of a shaft body, and an outer peripheral surface of the foamed elastic layer are disposed. An elastic roller is described that includes an adhesive layer in which cells existing in the vicinity of the outer peripheral surface are embedded, and a resin tube disposed on the outer peripheral surface of the adhesive layer.

JP 2012-233961 A

  The object of the present invention is to provide a tube-shaped surface layer between a tube-shaped surface layer and a substrate, as compared with a case where the inner layer side of the surface layer does not have a region having high gas permeability compared to the surface layer side. An object of the present invention is to provide a tubular body in which bubble formation between a layer and an elastic layer is suppressed, a fixing device including the tubular body, and an image forming apparatus.

The invention according to claim 1 has a tube-shaped surface layer on a substrate, or an elastic layer and a tube-shaped surface layer in order, and the surface layer is made of polystyrene, polyurethane, polybutadiene, ethyl cellulose. A first surface layer including at least one of cellulose acetate, polybutadiene, and polypropylene, and a second surface layer including a fluororesin on the surface layer side, the first surface The layer is high in gas permeability compared to the second surface layer, or the surface layer is configured to contain a fluororesin, and the inner layer side in the surface layer is higher in gas permeability than the surface layer side. It is a tubular body.

The invention according to claim 2 is the tubular body according to claim 1, wherein the thickness of the first surface layer or the thickness of the region having high gas permeability is in the range of 5 μm to 50 μm.

  The invention according to claim 3 is a fixing device including the tubular body according to claim 1 or 2 as a fixing member.

  According to a fourth aspect of the present invention, there is provided an image carrier, a latent image forming unit for forming a latent image on the surface of the image carrier, a developing unit for developing the latent image with toner to form a toner image, and a transfer A transfer unit that transfers the toner image to a recording medium by a member; and a fixing unit that fixes the toner image to the recording medium by a fixing member. At least one of the transfer member and the fixing member includes: An image forming apparatus which is a tubular body according to Item 1 or 2.

  According to the first aspect of the present invention, compared to the case where the inner layer side of the surface layer does not have a region having higher gas permeability than the surface layer side, the tube-like surface layer and the base material, or the tube A tubular body in which bubble formation between the surface layer and the elastic layer is suppressed is provided.

According to the invention which concerns on Claim 2, compared with the case where the thickness of a 1st surface layer or the area | region with high gas permeability is thinner than the said range, the tubular body from which bubble loss becomes short is provided.

  According to the invention which concerns on Claim 3, compared with the case where it does not have an area | region where gas permeability is high compared with the surface layer side in the inner layer side of the surface layer of a tubular body, it is between a tubular surface layer and a base material. Alternatively, there is provided a fixing device including a tubular body in which bubble formation between a tubular surface layer and an elastic layer is suppressed.

  According to the invention which concerns on Claim 4, compared with the case where it does not have a gas-permeable area | region compared with the surface layer side in the inner layer side of the surface layer of a tubular body, it is between a tubular surface layer and a base material. Alternatively, there is provided an image forming apparatus including a tubular body that suppresses bubble formation between a tubular surface layer and an elastic layer.

1 is a schematic configuration diagram illustrating an example of a fixing device according to an embodiment of the present invention. It is a schematic sectional drawing which shows an example of the laminated constitution of the tubular body which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the other example of the layer structure of the tubular body which concerns on embodiment of this invention. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Fixing device and tubular body>
An outline of an example of a fixing device according to an embodiment of the present invention is shown in FIG. Note that a fixing device employing an electromagnetic induction heating method will be described as an example of the fixing device in the present embodiment.

  As shown in FIG. 1, a fixing device 60 according to the present embodiment is disposed in pressure contact with a pressure roll 62 that is a rotatable pressure member, and a pressure roll 62 that is a pressure member. The unfixed toner image is fixed to the recording medium P by the recording medium P holding the unfixed toner image held between the pressurizing portions N (hereinafter also referred to as “nip portion N”) formed between A fixing belt 61 that is a rotatable tubular body, and a sliding sheet 68 that is interposed between the fixing belt 61 that is a tubular body and a pressing pad 64 that is a pressing member.

  The fixing device 60 is arranged so as to face the fixing belt 61, a fixing belt 61 that is a tubular body, a magnetic field generation unit 85 as an example of a heating member that generates heat from the magnetic field generated by an alternating current, and the fixing belt 61. A pressure roll 62 as an example of a pressure member, and a pressure pad 64 that is a pressure member that is pressed from the pressure roll 62 that is a pressure member via the fixing belt 61 are provided.

  The fixing belt 61, which is a tubular body, is rotatably supported by a pressure pad 64, a belt guide member 63, and edge guide members (not shown) disposed at both ends of the fixing belt 61. Then, it is brought into pressure contact with the pressure roll 62 at the pressure part (nip part) N, and is rotated in the arrow direction following the pressure roll 62.

  The fixing belt 61, which is a tubular body, has an elastic layer and a tube-shaped surface layer in order on a base material. The fixing belt 61 will be described later.

  The belt guide member 63 is attached to a holder 65 disposed inside the fixing belt 61. The belt guide member 63 is formed of a plurality of ribs (not shown) directed in the rotation direction of the fixing belt 61, and reduces the contact area with the inner peripheral surface of the fixing belt 61. Further, the belt guide member 63 is formed of a heat resistant resin such as PFA (perfluoroalkyl vinyl ether copolymer) or PPS (polyphenylene sulfide) having a low friction coefficient and low thermal conductivity. Thereby, the sliding resistance between the belt guide member 63 and the inner peripheral surface of the fixing belt 61 is reduced, and the heat divergence is reduced.

  The pressure pad 64 is pressed from the pressure roll 62 via the fixing belt 61 to form the pressure portion N. The pressing pad 64 that is a pressing member is supported by a holder 65 that is a holding member so as to press the pressure roll 62 with a load of, for example, 35 kgf by a spring or an elastic body. The pressing pad 64 includes, for example, an elastic body such as silicone rubber or fluorine rubber. The pressing pad 64 has a concave portion and a convex portion on the pressure roll 62 side. As a result, when the fixing belt 61 moves away from the surface of the pressing pad 64 on the pressure roll 62 side, a sudden change in curvature occurs, and the recording medium P after fixing is easily peeled off from the fixing belt 61.

  The peeling assisting member 70 disposed in the vicinity of the downstream side of the pressure unit N is held by the baffle holder 72 so that the peeling baffle 71 faces in the direction (counter direction) opposite to the rotation direction of the fixing belt 61. Further, a sliding sheet 68 is disposed between the pressing pad 64 and the fixing belt 61, and sliding resistance between the inner peripheral surface of the fixing belt 61 and the pressing pad 64 is reduced. In the present embodiment, the sliding sheet 68 is configured separately from the pressing pad 64, and at least both ends are fixed to the holder 65.

  A lubricant application member 67 is disposed in the holder 65 serving as a holding member over the longitudinal direction of the fixing device 60. The lubricant application member 67 is brought into contact with the inner peripheral surface of the fixing belt 61, and the lubricant is supplied to the sliding portion between the fixing belt 61 and the sliding sheet 68. Examples of the lubricant include liquid oils such as silicone oil and fluorine oil, grease obtained by mixing a solid substance and liquid, and combinations of these.

  The pressure roll 62 includes, for example, a solid iron base material (columnar core metal) 621 having a diameter of 16 mm, and an elastic layer 622 such as a silicone sponge having a thickness of 12 mm that covers the outer peripheral surface of the base material 621. For example, a surface layer 623 made of a heat-resistant resin coating such as PFA having a thickness of 30 μm or a heat-resistant rubber coating. In addition, as a manufacturing method of the pressure roll 62, for example, a fluororesin tube in which an adhesion primer is applied to the inner peripheral surface of a PFA tube (becomes the surface layer 623) and a solid shaft (becomes the base material 621) Is placed in a molding die, liquid foamed silicone rubber is injected between the fluororesin tube and the solid shaft, and then the silicone rubber is vulcanized and foamed by heat treatment (for example, 150 ° C., 2 hours) to form an elastic layer. The method of forming 622 is mentioned.

  The pressure roll 62 is disposed so as to face the fixing belt 61, and is rotated in the direction of arrow D at a process speed of, for example, 140 mm / sec to drive the fixing belt 61. Further, the fixing belt 61 is held between the pressing roll 62 and the pressing pad 64 to form a pressing portion N, and the recording medium P holding an unfixed toner image passes through the pressing portion N. The unfixed toner image is fixed on the recording medium P by applying heat and pressure.

  The magnetic field generation unit 85 has a cross-sectional shape that is curved along the shape of the fixing belt 61, and is installed with a clearance of, for example, about 0.5 mm to 2 mm from the outer peripheral surface of the fixing belt 61. The magnetic field generation unit 85 includes an excitation coil 851 that generates a magnetic field, a coil support member 852 that holds the excitation coil 851, and an excitation circuit 853 that supplies current to the excitation coil 851.

The exciting coil 851 is formed by, for example, forming litz wires, which are bundled from 16 to 20 copper wires having a diameter of 0.5 mm that are insulated from each other, and wound in a closed ring shape such as an oval shape, an elliptical shape, or a rectangular shape. Use what was done. When an alternating current having a predetermined frequency is applied to the exciting coil 851 by the exciting circuit 853, an alternating magnetic field H is generated around the exciting coil 851. When the alternating magnetic field H crosses the metal layer of the fixing belt 61, an eddy current I is generated so as to generate a magnetic field that hinders the change of the alternating magnetic field H by electromagnetic induction. The frequency of the alternating current applied to the exciting coil 851 is set, for example, from 10 kHz to 50 kHz. When the eddy current I flows through the metal layer of the fixing belt 61, Joule heat is generated by electric power W (W = I ² R) proportional to the resistance value R of the metal layer, and the fixing belt 61 is heated.

  The coil support member 852 is made of a nonmagnetic material having heat resistance, for example. Examples of such a nonmagnetic material include heat resistant resins such as heat resistant glass, polycarbonate, polyethersulfone, and PPS, or heat resistant resins obtained by mixing glass fibers with these.

  In the present embodiment, the electromagnetic induction heating type fixing device 60 including the magnetic field generation unit 85 has been described as an example of a heating member that heats the fixing belt 61. However, as the heating member, a radiation lamp heating element and a resistance heating element can be used. Can also be adopted.

  Examples of the radiant lamp heating element include a halogen lamp. Examples of the resistance heating element include iron-chromium-aluminum, nickel-chromium, platinum, molybdenum, tantalum, tungsten, silicon carbide, molybdenum-silicide, and carbon.

  In the fixing device 60, the fixing belt 61 is driven and rotated by the rotation of the pressure roll 62 in the direction of arrow D, and is exposed to the magnetic field generated by the excitation coil 851. At this time, an eddy current is generated in the metal layer in the fixing belt 61, and the outer peripheral surface of the fixing belt 61 is heated to a temperature at which fixing can be performed. The fixing belt 61 heated in this way moves to the pressure part N with the pressure roll 62. The recording medium P having the unfixed toner image provided on the surface thereof is carried into the fixing device 60 via the fixing inlet guide 56 by the conveying means. When the recording medium P passes through the pressure part N of the fixing belt 61 and the pressure roll 62, the unfixed toner image is heated by the fixing belt 61 and fixed on the surface of the recording medium P. Thereafter, the recording medium P on which the image is formed is conveyed by the conveying unit and is discharged from the fixing device 60. Also, the fixing belt 61 whose surface temperature on the outer peripheral surface has been lowered after the fixing process in the pressurizing unit N rotates in the direction of the excitation coil 851 and is heated again in preparation for the next fixing process.

  FIG. 2 is a schematic cross-sectional view illustrating an example of a layer configuration of the fixing belt 61 which is a tubular body in the fixing device according to the present embodiment. As shown in FIG. 2, the fixing belt 61 that is a tubular body has a base 611, an elastic layer 612, and a surface layer 613 in order, and the surface layer 613 includes a first surface layer 613 a and a second surface. A layer 613b. The inner layer side of the surface layer 613, that is, the first surface layer 613a is a high gas permeability region having higher gas permeability than the surface layer side of the surface layer 613, that is, the second surface layer 613b. The fixing belt 61 may be configured without the elastic layer 612.

  Conventionally, a fixing member or a transfer member in an image forming apparatus has a structure in which a surface layer is laminated on a substrate, or a structure in which an elastic layer and a surface layer are laminated in this order on a substrate. ing. For example, an elastomer material such as silicone rubber is used for the elastic layer, and a material such as a fluororesin having good releasability is used for the surface layer. A method of coating a tube-like film is known when forming this surface layer, but bubbles are interposed between the surface layer and the inner layer (base material or elastic layer) during this coating step. When subjected to high-temperature firing as it is, surface defects may occur, and the durability of the member may be reduced due to delamination between the surface layer and the elastic layer, or image defects may occur. In addition, when bubbles are present between the surface layer and the inner layer, the bubbles may be reduced by leaving for a long time (for example, 24 hours or more) before firing at high temperature. Shortening the time was desired.

  The present inventor has a case where the inner layer side of the surface layer has a region having a higher gas permeability than the surface layer side, so that the inner layer side of the surface layer does not have a region having a higher gas permeability than the surface layer side. In comparison, it was found that bubble formation between the tubular surface layer and the substrate or between the tubular surface layer and the elastic layer was suppressed. By suppressing the formation of bubbles, the adhesion failure between the surface layer and the elastic layer, the occurrence of delamination between the surface layer and the elastic layer starting from the bubbles, the occurrence of defects such as wrinkles are suppressed. Thus, the occurrence of image defects is suppressed, and the durability of the member is improved. Moreover, it is not necessary to leave for a long time before high temperature baking, and the process is shortened. This is because a gas passage is created by providing a region with high gas permeability on the inner layer side of the surface layer, and it is suppressed that bubbles are held between the surface layer and the inner layer. it is conceivable that.

  FIG. 3 is a schematic cross-sectional view illustrating another example of the layer configuration of the fixing belt 61 that is a tubular body in the fixing device according to the present embodiment. As shown in FIG. 3, the fixing belt 61 that is a tubular body includes a base 611, an elastic layer 612, and a surface layer 613 in order, and the inner layer side of the surface layer 613, that is, the elastic layer 612 side, A high gas permeable region 614 having higher gas permeability than the surface layer side of the layer 613 is formed. The fixing belt 61 may be configured without the elastic layer 612. In the configuration of FIG. 2, the surface layer 613 has a multi-layer configuration (two-layer configuration) of a first surface layer 613a and a second surface layer 613b. In the configuration of FIG. 1 layer configuration). Any configuration may be used as long as the inner layer side of the surface layer 613 has a region having higher gas permeability than the surface layer side.

  As shown in FIG. 2, when the surface layer 613 includes the first surface layer 613a and the second surface layer 613b having high gas permeability, examples of the material constituting the first surface layer 613a having high gas permeability include: And gas permeable resins such as polystyrene, polyurethane, polybutadiene, ethyl cellulose, cellulose acetate, polybutadiene, and polypropylene. Ethyl cellulose is preferred from the viewpoint of heat resistance.

  The material constituting the second surface layer 613b of FIG. 2 or the surface layer 613 of FIG. 3 is not particularly limited as long as it has an appropriate releasability with respect to the toner image. The surface layer is preferably formed with a fluorine compound as a main component. Examples of the fluorine compound include fluorine resins such as fluorine rubber, polytetrafluoroethylene (PTFE), perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene hexafluoropropylene copolymer (FEP). Can be mentioned.

  As shown in FIG. 3, when the inner layer side of the surface layer 613 is a high gas permeable region 614 having a high gas permeability, for example, the inner layer side is gradually cooled during extrusion molding of the surface layer 613, The gas permeability on the inner layer side of the surface layer 613 may be increased by increasing the crystallinity.

  The gas permeability (oxygen) T1 of the first surface layer 613a or the high gas permeability region 614 that is highly gas permeable is higher than the gas permeability (oxygen) T2 on the surface layer side of the second surface layer 613b or the surface layer 613. It is sufficient if it is high (T1> T2), for example, preferably 2 times or more of gas permeability (oxygen) T2, more preferably 10 times or more.

The gas permeability (oxygen) T1 of the first surface layer 613a or the high gas permeability region 614 is, for example, in a range of 2000 (cc / m ² · 24 h / atm) to 700000 (cc / m ² · 24 h / atm). It is preferable that If the gas permeability (oxygen) T1 is less than 2000 (cc / m ² · 24 h / atm), the bubble formation suppressing effect may be reduced, and if it exceeds 700000 (cc / m ² · 24 h / atm), Intermolecular cohesive force is reduced, and heat resistance may be reduced.

The gas permeability (oxygen) T2 on the surface layer side of the second surface layer 613b or the surface layer 613 is, for example, in the range of 0 (cc / m ² · 24 h / atm) to 1000 (cc / m ² · 24 h / atm). It is preferable that If the gas permeability (oxygen) T2 exceeds 1000 (cc / m ² · 24 h / atm), the pressure on the gas may decrease, and the gas flow for passing through the high permeability region may decrease.

  The thickness of the first surface layer 613a or the high gas permeability region 614 is, for example, preferably in the range of 5 μm to 50 μm, and more preferably in the range of 10 μm to 40 μm. If the thickness of the first surface layer 613a or the high gas permeability region 614 is less than 5 μm, the bubble formation suppressing effect may be reduced. If the thickness exceeds 50 μm, the thermal conductivity is lowered and the fixed image quality is lowered. There is a case.

  The thickness of the second surface layer 613b is, for example, preferably in the range of 10 μm to 50 μm, and more preferably in the range of 20 μm to 40 μm. When the thickness of the second surface layer 613b is less than 10 μm, the life of the tubular body may be extremely shortened from the viewpoint of wear resistance. When the thickness exceeds 50 μm, the bending stress increases and causes cracks. May end up.

  The thickness of the surface layer 613 having the configuration shown in FIG. 3 is preferably in the range of 10 μm to 100 μm, and more preferably in the range of 20 μm to 50 μm. If the thickness of the surface layer 613 is less than 10 μm, the temperature gradient between the surface side and the inner surface side during molding may be reduced, and it may be difficult to form a high gas permeable region. It may become large and cause cracks.

  Examples of the material constituting the base material 611 include one or more mixtures selected from thermosetting polyimide resins, thermoplastic polyimide resins, polyamide resins, polyamideimide resins, polybenzimidazole resins, and the like. From the viewpoints of heat resistance, mechanical properties and the like, a polyimide resin is preferable.

  The base material 611 may include a conductor such as carbon black. Alternatively, a two-layer configuration of a polyimide layer in which fluorine resin particles such as PTFE resin particles are dispersed and a polyimide layer in which a conductor such as carbon black is dispersed may be employed.

  The thickness of the base material 611 is, for example, in the range of not less than 10 μm and not more than 200 μm.

  The material constituting the elastic layer 612 may be a heat-resistant elastic body, and silicone rubber or the like is preferable.

  The thickness of the elastic layer 612 is, for example, in the range of 50 μm to 500 μm.

  Examples of a method for manufacturing the fixing belt 61 that is a tubular body shown in FIG. 2 include the following methods. Insert the base material into the elastic layer coating process mold, rotate it in the circumferential direction while keeping the mold axis direction substantially horizontal, and discharge the elastic layer forming coating solution from the nozzle at a predetermined discharge speed And discharging while moving at a predetermined moving speed. After the discharged elastic layer forming coating solution is leveled on a flat plate or the like as the nozzle moves, the coating solution on the mold is held while being rotated at a predetermined rotation speed and holding time until the coating solution is almost smooth. After the elastic layer forming coating solution is almost smooth, it is dried at a predetermined temperature and time (for example, 60 ° C. or higher and 110 ° C. or lower, 10 minutes or longer and 1 hour or lower) in a rotary drying furnace, and then predetermined. Vulcanization is performed at a temperature and time (for example, 150 ° C. to 250 ° C., 0.5 hour to 5 hours) to form an elastic layer. Prepare a fluororesin tube (becomes the surface layer 613) such as a PFA tube having a small diameter (for example, 90% or more and 101% or less) in a predetermined amount from the outer diameter of the tubular body formed up to the elastic layer. A fluororesin tube is set on the inner periphery of the outer mold having a large diameter (for example, 110% or more and 130% or less) in a predetermined amount from the outer shape of the tubular body. And in the state which inserted the tubular body formed to the elastic layer inside the fluororesin tube, a fluororesin tube is removed from an outer mold | type and coat | covers the outer periphery of an elastic layer. After standing at room temperature for a predetermined time (for example, 15 ° C. to 35 ° C., 10 hours to 200 hours), at a predetermined temperature and time (for example, 150 ° C. to 250 ° C., 0.5 hours to 5 hours) The surface layer may be formed by heating.

  Note that the fixing belt has been described as an example of the tubular body according to the present embodiment, but the present invention is not limited to this. For example, the fixing belt may be used as a conveyance belt or a transfer belt of an image forming apparatus.

[Image forming apparatus]
An image forming apparatus according to the present embodiment includes an image carrier, a latent image forming unit that forms a latent image on the surface of the image carrier, a developing unit that develops the latent image with toner to form a toner image, and a transfer A transfer unit that transfers the toner image to the recording medium by a member; and a fixing unit that fixes the toner image to the recording medium by a fixing member. At least one of the transfer member and the fixing member according to the present embodiment. It is a tubular member.

  FIG. 4 shows a schematic configuration of an example of an image forming apparatus to which the tubular member according to the present embodiment is applied. Here, an intermediate transfer type image forming apparatus generally called a tandem type will be described as an example.

  FIG. 4 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment. The image forming apparatus 100 in FIG. 4 is an intermediate transfer type image forming apparatus generally called a tandem type, and a plurality of image forming units 1Y, 1M, 1C, and 1K in which toner images of respective color components are formed by electrophotography. A primary transfer unit 10 that sequentially transfers (primary transfer) the color component toner images formed by the image forming units 1Y, 1M, 1C, and 1K to the intermediate transfer belt 15, and a superimposition transferred on the intermediate transfer belt 15. A secondary transfer unit 20 that batch-transfers (secondary transfer) toner images to a sheet P as a recording medium, and a fixing device 60 that fixes the secondary-transferred image on the sheet P are provided. The fixing device 60 may be a fixing device including the tubular member as a fixing belt, and the intermediate transfer belt 15 may be the tubular member. Further, the image forming apparatus 100 includes a control unit 40 that controls the operation of each device (each unit).

  Each of the image forming units 1Y, 1M, 1C, and 1K of the image forming apparatus 100 includes a photosensitive drum 11 that rotates in the direction of arrow A as an example of an image holding body that holds a toner image formed on the surface.

  A charging device 12 for charging the photosensitive drum 11 is provided around the photosensitive drum 11 as an example of a charging unit for charging the surface of the image carrier, and a latent image is formed on the surface of the image carrier charged by the charging unit. As an example of a latent image forming means for forming a laser beam, a laser exposure device 13 for writing an electrostatic latent image on the photosensitive drum 11 (the exposure beam is indicated by a symbol Bm in the figure) is provided. Further, around the photosensitive drum 11, each color component toner is accommodated as an example of a developing unit that forms a toner image by developing the latent image formed on the surface of the image holding member with the toner by the latent image forming unit. A developing device 14 is provided that visualizes the electrostatic latent image on the photosensitive drum 11 with toner, and each color component toner image formed on the photosensitive drum 11 is transferred to the intermediate transfer belt 15 by the primary transfer unit 10. A primary transfer roll 16 is provided for transferring the toner.

  Further, a drum cleaner 17 for removing residual toner on the photosensitive drum 11 is provided around the photosensitive drum 11, and a charger 12, a laser exposure device 13, a developing device 14, a primary transfer roll 16, and a drum cleaner are provided. Seventeen electrophotographic devices are sequentially arranged along the rotation direction of the photosensitive drum 11. These image forming units 1Y, 1M, 1C, and 1K are arranged substantially linearly in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15. Is done.

The intermediate transfer belt 15 that is an intermediate transfer member may be the above-described tubular member, or a film-like pressure belt containing a resin such as polyimide or polyamide as a base layer and containing an appropriate amount of an antistatic agent such as carbon black. It may be configured by. The volume resistivity is formed to be, for example, 10 ⁶ Ωcm or more and 10 ¹⁴ Ωcm or less, and the thickness thereof is configured to be, for example, about 0.1 mm.

  The intermediate transfer belt 15 is circulated (rotated) at a predetermined speed in the direction B shown in FIG. 4 by various rolls. As these various rolls, a drive roll 31 that is driven by a motor (not shown) having excellent constant speed and rotates the intermediate transfer belt 15, and an intermediate transfer that extends substantially linearly along the arrangement direction of the photosensitive drums 11. A support roll 32 that supports the belt 15, a tension roll 33 that functions as a correction roll that applies a predetermined tension to the intermediate transfer belt 15 and suppresses meandering of the intermediate transfer belt 15, and a backup provided in the secondary transfer unit 20. A roll 25 and a cleaning backup roll 34 provided in a cleaning unit that scrapes residual toner on the intermediate transfer belt 15 are provided.

The primary transfer unit 10 includes a primary transfer roll 16 that is disposed to face the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The primary transfer roll 16 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is, for example, a cylindrical bar made of a metal such as iron or SUS. The sponge layer is formed of, for example, a blend rubber of nitrile rubber (NBR), styrene rubber (SBR), and ethylene propylene rubber (EPDM) containing a conductive agent such as carbon black, and has a volume resistivity of 10 ^7. It is a sponge-like cylindrical roll of ⁵ Ωcm or more and 10 ^8.5 Ωcm or less.

  The primary transfer roll 16 is disposed in pressure contact with the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. Further, the primary transfer roll 16 has a voltage (for example, negative polarity; the same applies hereinafter) having a polarity opposite to that of the toner. (Primary transfer bias) is applied. As a result, the toner images on the respective photosensitive drums 11 are sequentially electrostatically attracted to the intermediate transfer belt 15 so as to form superimposed toner images on the intermediate transfer belt 15.

  The secondary transfer unit 20 is a secondary transfer disposed on the toner image holding surface side of the intermediate transfer belt 15 as an example of a transfer unit that transfers a toner image formed by the backup roll 25 and the developing unit to a recording medium. And a roll 22.

The backup roll 25 is made of, for example, a tube of EPDM and NBR blend rubber having a surface dispersed with carbon, and the inside is made of EPDM rubber. And it is formed so that the surface resistivity may be, for example, 10 ⁷ Ω / □ or more and 10 ¹⁰ Ω / □ or less, and the hardness is, for example, 70 ° (Asker C: manufactured by Kobunshi Keiki Co., Ltd.). Set to The backup roll 25 is disposed on the back side of the intermediate transfer belt 15 to constitute a counter electrode of the secondary transfer roll 22, and a metal power supply roll 26 to which a secondary transfer bias is stably applied is disposed in contact with the backup roll 25. ing.

The secondary transfer roll 22 includes, for example, a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is, for example, a cylindrical bar made of a metal such as iron or SUS. The sponge layer is formed of, for example, a blend rubber of NBR, SBR, and EPDM mixed with a conductive agent such as carbon black. For example, the sponge layer has a volume resistivity of 10 ^7.5 Ωcm to 10 ^8.5 Ωcm. It is a cylindrical roll.

  The secondary transfer roll 22 is disposed in pressure contact with the backup roll 25 with the intermediate transfer belt 15 interposed therebetween. Further, the secondary transfer roll 22 is grounded to form a secondary transfer bias between the secondary transfer roll 22 and the secondary transfer roll 25. The toner image is secondarily transferred onto the paper P conveyed to the unit 20.

  On the downstream side of the secondary transfer portion 20 of the intermediate transfer belt 15, an intermediate transfer belt cleaner that removes residual toner, paper dust, and the like on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15. 35 is provided detachably.

  On the upstream side of the yellow image forming unit 1Y, a reference sensor (home position sensor) 42 that generates a reference signal serving as a reference for taking image forming timings in the image forming units 1Y, 1M, 1C, and 1K is disposed. Is done. Further, an image density sensor 43 for adjusting image quality is disposed on the downstream side of the black image forming unit 1K. The reference sensor 42 recognizes a predetermined mark provided on the back side of the intermediate transfer belt 15 and generates a reference signal. Each image forming unit is instructed by an instruction from the control unit 40 based on the recognition of the reference signal. 1Y, 1M, 1C, and 1K are configured to start image formation.

  In the image forming apparatus 100 according to the present embodiment, as a transport unit that transports the paper P, the paper storage unit 50 that stores the paper P, and the paper P accumulated in the paper storage unit 50 is taken out and transported at a predetermined timing. A paper feed roll 51, a transport roll 52 that transports the paper P fed by the paper feed roll 51, a transport guide 53 that feeds the paper P transported by the transport roll 52 to the secondary transfer unit 20, and the secondary transfer roll 22. A conveyance belt 55 that conveys the sheet P conveyed after the secondary transfer to the fixing device 60 and a fixing entrance guide 56 that guides the sheet P to the fixing device 60 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 100 shown in FIG. 4, image data output from an image reading device (not shown) or a personal computer (PC) (not shown) is subjected to predetermined image processing by an image processing device (not shown), and then image formation is performed. Image forming work is executed by the units 1Y, 1M, 1C, and 1K.

  In the image processing apparatus 100, a predetermined image such as shading correction, position shift correction, lightness / color space conversion, gamma correction, frame deletion, color editing, movement editing, or the like is applied to the input reflectance data. Processing is performed. The image data that has been subjected to image processing is converted into color material gradation data of four colors Y, M, C, and K, and is output to the laser exposure unit 13.

  The laser exposure unit 13 irradiates, for example, an exposure beam Bm emitted from a semiconductor laser to the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K according to the input color material gradation data. In each of the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, the surface is charged by the charger 12, and then the surface is scanned and exposed by the laser exposure unit 13 to form an electrostatic latent image. The formed electrostatic latent image is developed as a toner image of each color of Y, M, C, K by each image forming unit 1Y, 1M, 1C, 1K.

  The toner images formed on the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 in the primary transfer unit 10 where the photosensitive drums 11 and the intermediate transfer belt 15 are in contact with each other. Transcribed. More specifically, in the primary transfer unit 10, a voltage (primary transfer bias) having a polarity opposite to the charging polarity (for example, negative polarity) of toner is applied to the base material of the intermediate transfer belt 15 by the primary transfer roll 16, and the toner Primary transfer is performed by sequentially superimposing images on the surface of the intermediate transfer belt 15.

  After the toner images are sequentially primary transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner image is conveyed to the secondary transfer unit 20. When the toner image is transported to the secondary transfer unit 20, the transport unit rotates the paper feed roll 51 in accordance with the timing at which the toner image is transported to the secondary transfer unit 20, and the predetermined value is set in advance from the paper storage unit 50. A size paper P is supplied. The paper P supplied by the paper feed roll 51 is transported by the transport roll 52, and reaches the secondary transfer unit 20 through the transport guide 53. Before reaching the secondary transfer unit 20, the paper P is temporarily stopped, and the registration roller (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 on which the toner image is held. And the position of the toner image are aligned.

  In the secondary transfer unit 20, the secondary transfer roll 22 is pressed against the backup roll 25 via the intermediate transfer belt 15. At this time, the sheet P conveyed at the same timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. At this time, when a voltage (secondary transfer bias) having the same polarity as the toner charging polarity (for example, negative polarity) is applied from the power supply roll 26, a transfer electric field is generated between the secondary transfer roll 22 and the backup roll 25. It is formed. The unfixed toner image held on the intermediate transfer belt 15 is collectively electrostatically transferred onto the paper P in the secondary transfer unit 20 pressed by the secondary transfer roll 22 and the backup roll 25. 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 15 by the secondary transfer roll 22, and transported downstream of the secondary transfer roll 22 in the sheet transport direction. It is conveyed to the belt 55. The conveyance belt 55 conveys the paper P to the fixing device 60 in accordance with the optimum conveyance speed in the fixing device 60. The unfixed toner image on the paper P conveyed to the fixing device 60 is fixed on the paper P by being subjected to a fixing process by heat and pressure by the fixing device 60. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge accommodating portion (not shown) provided in the discharge portion 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 15 is conveyed to the cleaning unit as the intermediate transfer belt 15 rotates, and is cleaned by the cleaning backup roll 34 and the intermediate transfer belt cleaner 35. It is removed from the intermediate transfer belt 15.

  Although the embodiments of the present invention have been described above, the present invention is not construed as being limited to the above-described embodiments, and various modifications, changes, and improvements can be made, and a range that satisfies the requirements of the present invention. Needless to say, this is feasible.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

[Production of substrate]
A polyamic acid solution having a solid content concentration of 18% by mass using NMP (N-methylpyrrolidone) as a solvent is prepared, the polyamic acid solution is injected into a centrifugal mold that is an aluminum cylinder, and the centrifugal mold is rotated around its axis. A coating film was formed and dried by heating at 145 ° C. for 30 minutes to obtain a dried film. The dried film was removed from the centrifugal mold and set in an imidized mold, and heated at 200 ° C. for 20 minutes and 380 ° C. for 20 minutes to obtain an endless belt-like polyimide base material layer having an inner diameter of 168 mm and a film thickness of 80 μm.

[Formation of elastic layer]
On the base material obtained as described above, an elastic layer was formed as follows. The base material was inserted into the elastic layer coating step mold and placed on a turntable that rotated in the circumferential direction while keeping the mold axis direction substantially horizontal. The mold is rotated at 100 rpm, and a liquid silicone rubber coating solution for forming an elastic layer (containing 85 mass% of silicone rubber (X-34-2086A / B manufactured by Shin-Etsu Chemical Co., Ltd.) in a solvent (butyl acetate)) from the nozzle every minute. It was discharged while moving at a rate of 160 mm / min from the end of the mold at 45 mL. After the discharged silicone rubber coating solution is smoothed by a flat SUS plate with a thickness of 0.1 mm as the nozzle moves, the coating solution is kept rotating at 50 rpm for 5 minutes until the coating solution on the mold is almost smooth. did. After the silicone rubber coating solution became almost smooth, it was dried at 110 ° C. for 20 minutes in a rotary drying furnace, and subsequently vulcanized at 210 ° C. for 1 hour. The film thickness of the obtained elastic layer was 450 μm.

[Formation of surface layer]
A 35 μm thick PFA tube having a diameter 2% smaller than the outer diameter of the tubular body formed up to the elastic layer is prepared, and the PFA tube is disposed on the inner periphery of the outer mold whose inner diameter is 0.8% larger than the outer diameter of the tubular body. I set it. And in the state which inserted the tubular body formed to the elastic layer inside the PFA tube, the PFA tube was removed from the outer mold | type and it coat | covered the outer periphery of the elastic layer. After leaving at room temperature (25 ° C.) for 24 hours, it was heated at 200 ° C. for 30 minutes to form a surface layer having a thickness of 35 μm.
The belt having the substrate / elastic layer / surface layer in this order was produced.

<Example 1>
As a PFA tube used for forming the surface layer in the belt production process, the inner layer side has a high degree of crystallinity, i.e., has a high gas permeability region on the inner layer side that is higher in gas permeability than the surface layer side. A fixing belt was produced. This PFA tube was produced by gradually cooling the inner layer side from 300 ° C. to 25 ° C. at a rate of 20 ° C./min when the PFA tube was extruded to increase the crystallinity of the inner layer side. When measured using a multilayer film thickness measuring machine (manufactured by Keyence, SI-T type), the thickness of the high gas permeable region was 10 μm. Moreover, when measured by the method of JIS K 7126 using a gas permeability measuring device (manufactured by GL Sciences, GTME 2510 type), the gas permeability (oxygen) T1 on the inner layer side is 2000 (cc / m ² · 24 h / gas permeability (oxygen) T2 on the surface layer side was 100 (cc / m ² · 24 h / atm).

<Example 2>
As a PFA tube used for forming the surface layer in the belt manufacturing process, about 40% by mass of PFA powder (MP320, DuPont) is dispersed in an MEK solvent on an ethyl cellulose film (thickness 10 μm), subjected to ultrasonic treatment several times, and PFA dispersed. A product was made. A MEK solution containing poly (propylene carbonate) (PPC) (QPAC40, Empower Materials) having a molecular weight of about 265,000 g / mol is added to the PFA dispersion, and the coating dispersion contains 10% by weight polypropylene carbonate. A product was made. The coating dispersion was applied by flow coating. It was fired at 250 ° C. for 30 minutes to remove polypropylene carbonate, and further fired at 350 ° C. for 8 minutes to melt the PFA. A fixing belt was produced using the produced first surface layer (thickness 10 μm) having an ethyl cellulose film having high gas permeability and the second surface layer (thickness 25 μm) having a PFA tube. The gas permeability (oxygen) T1 of the first surface layer on the inner layer side is 35000 (cc / m ² · 24 h / atm), and the gas permeability (oxygen) T2 of the second surface layer on the surface layer side is 100 ( cc / m ² · 24 h / atm).

<Example 3>
A fixing belt was produced in the same manner as in Example 1 except that in the production of the PFA tube, the inner layer side was gradually cooled from 300 ° C. to 25 ° C. at a rate of 10 ° C./min. The gas permeability (oxygen) T1 of the first surface layer on the inner layer side is 4000 (cc / m ² · 24 h / atm), and the gas permeability (oxygen) T2 of the second surface layer on the surface layer side is 100 ( cc / m ² · 24 h / atm).

<Example 4>
In the production of the PFA tube, a fixing belt was produced in the same manner as in Example 2 except that a polyurethane film (thickness: 10 μm) was used instead of the ethyl cellulose film. The gas permeability (oxygen) T1 of the first surface layer on the inner layer side is 3000 (cc / m ² · 24 h / atm), and the gas permeability (oxygen) T2 of the second surface layer on the surface layer side is 100 ( cc / m ² · 24 h / atm).

<Example 5>
A fixing belt was produced in the same manner as in Example 2 except that an ethylcellulose film having a thickness of 50 μm was used in the production of the PFA tube. The gas permeability (oxygen) T1 of the first surface layer on the inner layer side is 35000 (cc / m ² · 24 h / atm), and the gas permeability (oxygen) T2 of the second surface layer on the surface layer side is 100 ( cc / m ² · 24 h / atm).

<Example 6>
A fixing belt was produced in the same manner as in Example 2 except that an ethylcellulose film having a thickness of 1 μm was used in the production of the PFA tube. The gas permeability (oxygen) T1 of the first surface layer on the inner layer side is 35000 (cc / m ² · 24 h / atm), and the gas permeability (oxygen) T2 of the second surface layer on the surface layer side is 100 ( cc / m ² · 24 h / atm).

<Example 7>
A fixing belt was prepared in the same manner as in Example 2 except that an ethyl cellulose film having a thickness of 100 μm was used in the production of the PFA tube. The gas permeability (oxygen) T1 of the first surface layer on the inner layer side is 35000 (cc / m ² · 24 h / atm), and the gas permeability (oxygen) T2 of the second surface layer on the surface layer side is 100. there were.

<Example 8>
A fixing belt was produced in the same manner as in Example 2 except that an ethylcellulose film having a thickness of 1 μm was used in the production of the PFA tube. The gas permeability (oxygen) T1 of the first surface layer on the inner layer side is 35000 (cc / m ² · 24 h / atm), and the gas permeability (oxygen) T2 of the second surface layer on the surface layer side is 100 ( cc / m ² · 24 h / atm).

<Comparative Example 1>
A fixing belt was produced using a PFA tube (Gunze, thickness 35 μm) as the PFA tube used for forming the surface layer in the belt production process. The gas permeability (oxygen) of the PFA tube was 1 (cc / m ² · 24 h / atm).

<Comparative example 2>
In the production of the PFA tube, a fixing belt was produced in the same manner as in Example 2 except that a polyvinylidene fluoride film (thickness 10 μm) was used instead of the ethyl cellulose film. The gas permeability (oxygen) T1 of the first surface layer on the inner layer side is 20 (cc / m ² · 24 h / atm), and the gas permeability (oxygen) T2 of the second surface layer on the surface layer side is 100 ( cc / m ² · 24 h / atm).

[Evaluation method]
(Bubble generation suppression effect)
In the preparation of the fixing belt, the size of bubbles generated between the elastic layer and the surface layer after 10 minutes after the PFA tube is removed from the outer mold and coated on the outer periphery of the elastic layer is measured using a scale. The time until the bubbles disappeared was measured. Evaluation was made according to the following criteria. The results are shown in Table 1.
"Bubble size"
○: Less than 0.1 mm ×: 0.1 mm or more “Bubble disappearance time”
○: Less than 24 hours ×: More than 24 hours

(Belt durability and image quality evaluation)
The surface layer and elastic layer of the fixing belt after being mounted on an image forming apparatus (Fuji Xerox Co., Ltd., Color 1000 Press type) as a fixing belt and forming 10,000 sheets of images on plain paper, 100 ppm, room temperature and normal humidity. The presence or absence of delamination and the presence or absence of image quality defects were evaluated visually. The results are shown in Table 1.

  Thus, compared with the comparative example which does not have the area | region where gas permeability is high compared with the surface layer side in the inner layer side of a surface layer, an Example WHEREIN: Bubble formation between a tubular surface layer and an elastic layer Was suppressed.

  1Y, 1M, 1C, 1K Image forming unit, 10 Primary transfer unit, 11 Photosensitive drum, 12 Charger, 13 Laser exposure unit, 14 Developer, 15 Intermediate transfer belt, 16 Primary transfer roll, 17 Drum cleaner, 20 2 Next transfer section, 22 Secondary transfer roll, 25 Backup roll, 26 Feed roll, 31 Drive roll, 32 Support roll, 33 Tension roll, 34 Cleaning backup roll, 35 Intermediate transfer belt cleaner, 40 Control section, 42 Reference sensor (home Position sensor), 43 image density sensor, 50 paper storage unit, 51 paper feed roll, 52 transport roll, 53 transport guide, 55 transport belt, 56 fixing inlet guide, 60 fixing device, 61 fixing belt, 62 pressure roll, 63 Belt guide member, 64 pressure pad 65, 65 holder, 67 Lubricant application member, 68 Sliding sheet, 70 Peeling auxiliary member, 71 Peeling baffle, 72 Baffle holder, 85 Magnetic field generation unit, 100 Image forming apparatus, 611 Base material, 612 Elastic layer, 613 Surface layer , 613a First surface layer, 613b Second surface layer, 614 High gas permeability region, 621 base material, 622 elastic layer, 623 surface layer, 851 excitation coil, 852 coil support member, 853 excitation circuit.

Claims (4)

On the substrate, it has a tube-shaped surface layer, or has an elastic layer and a tube-shaped surface layer sequentially,
The surface layer includes a first surface layer including at least one of polystyrene, polyurethane, polybutadiene, ethyl cellulose, cellulose acetate, polybutadiene, and polypropylene, and a fluorine resin on the surface layer side. Two surface layers, and the first surface layer has higher gas permeability than the second surface layer, or
The said surface layer is comprised including a fluororesin, and the inner layer side in the said surface layer has high gas permeability compared with the surface layer side, The tubular body characterized by the above-mentioned . 2. The tubular body according to claim 1, wherein the thickness of the first surface layer or the thickness of the region having high gas permeability is in a range of 5 μm to 50 μm.   A fixing device comprising the tubular body according to claim 1 or 2 as a fixing member. An image carrier,
Latent image forming means for forming a latent image on the surface of the image carrier;
Developing means for developing the latent image with toner to form a toner image;
Transfer means for transferring the toner image to a recording medium by a transfer member;
Fixing means for fixing the toner image to the recording medium by a fixing member;
With
3. The image forming apparatus according to claim 1, wherein at least one of the transfer member and the fixing member is a tubular body according to claim 1.

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