JP2010197836A - Endless belt, fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endless belt in which generation of cracks by repeated deformation in use is reduced in a metal belt. <P>SOLUTION: A fixing belt 61 which is the endless belt forms a long cylindrical shape of three layer structure provided with: a metal layer 61a; an elastic layer 61b; and a release layer 61c in order from the inner peripheral side. The inner peripheral surface of the metal layer 61a is the inner surface 61i of the fixing belt 61, and the outer circumferential surface of the release layer 61c is the outer surface 61o of the fixing belt 61. The metal layer 61a is the endless (seamless) belt without a joint on the side, and forms multilayer structure of three layers. Three layers are: a base metal layer of stainless steel; a heat-generating metal layer of copper; and a middle metal layer of stainless steel from the inside. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

In recent years, in an electrophotographic image forming apparatus, it has been proposed to use a metal belt excellent in strength as a fixing belt in order to meet the demand for higher speed of a heating type fixing device.
In Patent Document 1, an unfixed toner image formed on a sheet is melted by heating through a seamless belt that is metallic by an electroforming process and has a surface roughness of less than 0.5 μm on the surface in contact with the heating element. An apparatus for fixing a toner image on a sheet is described.
In Patent Document 2, as such a metal fixing belt, micro Vickers hardness made of nickel-manganese alloy containing 0.05 to 0.6% by weight of manganese, which has excellent thermal conductivity and high dimensional accuracy, is disclosed. A fixing belt formed by using an endless electroformed sheet of 450 to 650 as a base is described.

Japanese Patent Laid-Open No. 7-13448 JP-A-9-34286

  By the way, for example, in the case of a metal that can use an electroforming technique such as nickel, the metal belt is formed by an electroforming method, and when a stainless alloy, a nickel alloy, or the like is used, it is formed by a plastic working method or the like.

  An object of the present invention is to provide an endless belt in which occurrence of cracks due to repeated deformation during use is reduced in a metal belt.

According to the first aspect of the present invention, chromium is 15% by weight to 19% by weight, nickel is 6% by weight to 10% by weight, manganese is 1% by weight to 3% by weight, copper is 2% by weight to 5% by weight. An endless belt comprising: a cylindrical metal layer having at least one stainless steel layer containing at most%; and a release layer laminated on the outside of the metal layer.
The invention according to claim 2 is the endless belt according to claim 1, wherein the metal layer includes a plurality of the stainless steel layers and a copper layer sandwiched between the stainless steel layers. is there.
The invention according to claim 3 is the endless belt according to claim 1 or 2, wherein the stainless steel layer of the metal layer has a carbon content of 0.1 wt% or less.
The invention according to claim 4 is the endless belt according to any one of claims 1 to 3, wherein the stainless steel layer of the metal layer has a work hardening coefficient of 0.4 or less. is there.
The invention according to claim 5 is the endless belt according to any one of claims 1 to 4, further comprising an elastic layer between the metal layer and the release layer.

The invention according to claim 6 is chromium 15 wt% or more and 19 wt% or less, nickel 6 wt% or more and 10 wt% or less, manganese 1 wt% or more and 3 wt% or less, copper 2 wt% or more and 5 wt%. %, A fixing metal belt having a cylindrical metal layer having at least one stainless steel layer containing at least one layer, and a release layer laminated on the outside of the metal layer, and pressure applied to the outside of the fixing belt A fixing device comprising: a member; and a heating member that is provided inside the fixing belt and heats the fixing belt.
According to a seventh aspect of the present invention, in the fixing device according to the sixth aspect, a repetitive strain width received by the fixing belt is 0.7% or more.
The invention according to claim 8 is characterized in that the heating member is an electromagnetic induction heating member that generates an eddy current in the metal layer of the fixing belt and generates heat in the fixing belt. The fixing device described.

  The invention according to claim 9 is an image forming portion for forming a toner image, a transfer portion for transferring a toner image formed by the image forming portion to a recording material, 15% by weight to 19% by weight of chromium, A cylindrical metal layer having at least one stainless steel layer containing nickel 6 wt% or more and 10 wt% or less, manganese 1 wt% or more and 3 wt% or less, copper 2 wt% or more and 5 wt% or less, A fixing belt having a release layer laminated on the outside of the metal layer, a pressure member that forms a pressing portion between the fixing belt and is driven to rotate, and is provided inside the fixing belt. An image forming apparatus comprising: a heating member that heats the fixing belt; and a fixing unit that fixes the toner image transferred to the recording material to the recording material.

According to the first aspect of the present invention, the occurrence of cracks due to repeated deformation during use can be reduced as compared with the case where the present configuration is not provided.
According to the invention of claim 2, the heating efficiency of the endless belt is improved as compared with the case where the present configuration is not provided.
According to invention of Claim 3, compared with the case where it does not have this structure, generation | occurrence | production of the crack by the repeated deformation at the time of use can be reduced more.
According to the fourth aspect of the present invention, the repeated deformation during use can be made larger than when the present configuration is not provided.
According to invention of Claim 5, the elasticity of an endless belt improves compared with the case where it does not have this structure.
According to the sixth aspect of the present invention, stable fixing is performed as compared with the case where this configuration is not provided.
According to the seventh aspect of the present invention, the recording paper can be easily peeled off from the fixing belt after fixing as compared with the case where the present configuration is not provided.
According to the eighth aspect of the present invention, the heat fixing can be performed by the heat generated by the fixing belt as compared with the case where the present configuration is not provided.
According to the ninth aspect of the present invention, stable image formation is performed as compared with the case where this configuration is not provided.

1 is a schematic configuration diagram of an example of an image forming apparatus to which the exemplary embodiment is applied. 2 is a diagram illustrating an example of a configuration of a fixing device. FIG. It is a figure for demonstrating an example of the Nip distortion which a pressure pad gives to a fixing belt. 2 is a cross-sectional view illustrating an example of a configuration of a fixing belt to which the exemplary embodiment is applied. FIG. FIG. 2 is a cross-sectional view illustrating an example of a configuration of a fixing belt to which the exemplary embodiment is applied in more detail.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. Also, the drawings used are used to describe the present embodiment and do not represent the actual size.

(Image forming apparatus 100)
FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus 100 to which the exemplary embodiment is applied. Here, an intermediate transfer type image forming apparatus 100 generally called a tandem type will be described as an example.
An image forming apparatus 100 illustrated in FIG. 1 includes a plurality of image forming units 1Y, 1M, 1C, and 1K that form toner images of respective color components by an electrophotographic method as an example of an image forming unit. Next, as an example of the transfer unit, the image forming apparatus 100 sequentially transfers (primary transfer) each color component toner image formed by each image forming unit 1Y, 1M, 1C, 1K to the intermediate transfer belt (image holding member) 15. And a secondary transfer unit 20 that collectively transfers (secondary transfer) the superimposed toner image transferred onto the intermediate transfer belt 15 onto a sheet of recording paper P (recording material). Further, the image forming apparatus 100 includes a fixing device 60 that fixes the second transferred image on the recording paper P as an example of a fixing unit. In addition, the image forming apparatus 100 includes a control unit 40 that controls the operation of each device (each unit).

  As shown in FIG. 1, each of the image forming units 1Y, 1M, 1C, and 1K includes a photosensitive drum 11 that rotates in the direction of arrow A, a charger 12 that charges the photosensitive drum 11, and a photosensitive drum 11. It has a laser exposure device 13 for writing an electrostatic latent image, and a developing device 14 that accommodates each color component toner and visualizes the electrostatic latent image on the photosensitive drum 11 with the toner. Further, a primary transfer roll 16 that transfers each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15 in the primary transfer unit 10, a drum cleaner 17 that removes residual toner on the photosensitive drum 11, and Have 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. ing.

  The intermediate transfer belt 15 is circulated and driven in the direction of arrow B shown in FIG. As various rolls, a drive roll 31 that drives the intermediate transfer belt 15, a support roll 32 that supports the intermediate transfer belt 15, a tension roll 33 that applies a constant tension to the intermediate transfer belt 15 to prevent meandering, and a secondary transfer. A backup roll 25 provided in the section 20 and a cleaning backup roll 34 provided in a cleaning section for scraping the residual toner on the intermediate transfer belt 15 are provided.

  The primary transfer unit 10 includes a primary transfer roll 16 that faces the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The secondary transfer unit 20 is disposed on the back side of the intermediate transfer belt 15 as a secondary transfer roll (transfer member) 22 disposed on the toner image holding surface side of the intermediate transfer belt 15 and a counter electrode of the secondary transfer roll 22. And a power supply roll 26 that applies a secondary transfer bias to the backup roll 25.

  An intermediate transfer belt cleaner 35 for removing residual toner and paper dust on the intermediate transfer belt 15 is provided on the downstream side of the secondary transfer unit 20. A reference sensor (home position sensor) 42 that generates a reference signal for taking an image forming timing in each of the image forming units 1Y, 1M, 1C, and 1K is disposed upstream of the yellow image forming unit 1Y. Further, an image density sensor 43 for adjusting image quality is disposed on the downstream side of the black image forming unit 1K.

  The recording paper transport system includes a paper storage unit 50, a pickup roll 51 that takes out and transports the recording paper P in the paper storage unit 50, a transport roll 52 that transports the recording paper P, and a secondary transfer of the recording paper P. A conveyance chute 53 to be fed to the unit 20, a conveyance belt 55 for conveying the recording paper P secondarily transferred by the secondary transfer roll 22 to the fixing device 60, and a fixing inlet guide 56 for guiding the recording paper P to the fixing device 60. And have.

A basic image forming process of the image forming apparatus 100 will be described.
In an image forming apparatus 100 as shown in FIG. 1, after image processing is performed on image data output from an image reading apparatus (not shown) or the like, the image data is converted into four colors Y, M, C, and K. It is converted into material gradation data and output to the laser exposure unit 13. For example, each of the photosensitive drums that rotates the exposure beam Bm emitted from the semiconductor laser in the direction of arrow A of the image forming units 1Y, 1M, 1C, and 1K according to the input color material gradation data. 11 is irradiated. After the surface of each photoconductive drum 11 is charged by the charger 12, the surface is scanned and exposed by the laser exposure device 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, and K by each of the image forming units 1Y, 1M, 1C, and 1K.

Next, the toner image formed on the photosensitive drum 11 is sequentially superimposed on the surface of the intermediate transfer belt 15 in the primary transfer unit 10 to perform primary transfer. The intermediate transfer belt 15 moves in the arrow B direction and conveys the toner image to the secondary transfer unit 20. The recording paper transport system supplies the recording paper P from the paper storage unit 50 at the timing when the toner image is transported to the secondary transfer unit 20.
In the secondary transfer unit 20, the unfixed toner image held on the intermediate transfer belt 15 is electrostatically transferred onto the recording paper P sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. Thereafter, the recording paper P on which the toner image is electrostatically transferred is transported to the fixing device 60 by the transport belt 55, and the fixing device 60 processes the unfixed toner image on the recording paper P with heat and pressure and puts it on the recording paper P. To settle. The recording 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 100.

(Fixing device 60)
Next, the fixing device 60 in the present embodiment will be described.
FIG. 2 is a diagram illustrating an example of the configuration of the fixing device 60. In the present embodiment, a fixing device 60 that employs an electromagnetic induction heating method will be described as an example.
2A, the fixing device 60 includes a fixing belt 61 that is an endless belt, a magnetic field generation unit 85 as an example of an electromagnetic induction heating member that generates heat by a magnetic field generated by an alternating current, a fixing belt, and the like. A pressure roll 62 as an example of a pressure member and a pressure pad 64 pressed from the pressure roll 62 via the fixing belt 61 are disposed so as to face the pressure member 61.

The fixing belt 61 which is an endless belt 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 a nip (Nip) portion N that is a pressing portion, and is rotated in the direction of arrow E following the pressure roll 62.
Details of 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 by a plurality of ribs (not shown) directed in the rotation direction of the fixing belt 61 to reduce 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. Thus, 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 nip portion N. The pressure pad 64 supports the pressure roll 62 by a holder 65 so as to press the pressure roll 62 with a load of, for example, 35 kgf by a spring or an elastic body. The pressure pad 64 is made of an elastic body such as silicone rubber or fluorine rubber. The pressure 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 pressure pad 64 on the pressure roll 62 side, a sudden change in curvature occurs, and the recording paper P after fixing is easily peeled off from the fixing belt 61. Therefore, the fixing belt 61 repeatedly receives a predetermined distortion (Nip distortion) at the nip portion N.

The peeling assisting member 70 disposed in the vicinity of the downstream side of the nip portion 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 low friction sheet 68 is disposed between the pressure pad 64 and the fixing belt 61 to reduce the sliding resistance between the inner peripheral surface of the fixing belt 61 and the pressure pad 64. In the present embodiment, the low friction sheet 68 is configured separately from the pressure pad 64, and both ends are fixed to the holder 65.
A lubricant application member 67 is disposed in the holder 65 over the longitudinal direction of the fixing device 60. The lubricant application member 67 contacts the inner peripheral surface of the fixing belt 61 and supplies the lubricant to the sliding portion between the fixing belt 61 and the low friction sheet 68. Examples of the lubricant include liquid oils such as silicone oil and fluorine oil; grease in which a solid substance and a liquid are mixed, and a combination thereof.

The pressure roll 62 includes, for example, a solid iron core (columnar core) 621 having a diameter of 16 mm, a rubber layer 622 such as a silicone sponge having a thickness of 12 mm, which covers the outer peripheral surface of the core 621, and the like, for example And a surface layer 623 with 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 core 621) are used. After setting in a molding die and injecting a liquid foamed silicone rubber between the fluororesin tube and the solid shaft, the silicone rubber is vulcanized and foamed by heat treatment (150 ° C., 2 hours) to form a rubber layer 622. The method of forming is mentioned.
The pressure roll 62 is disposed so as to face the fixing belt 61, rotates in the direction of arrow D at a process speed of, for example, 140 mm / sec, and drives the fixing belt 61. Further, the fixing belt 61 is held by the pressure roll 62 and the pressure pad 64 to form the nip portion N, and the recording paper P holding the unfixed toner image is passed through the nip portion N to pass the heat. And the pressure is applied to fix the unfixed toner image on the recording paper P.

  The magnetic field generation unit 85 has a round shape with a cross section that follows the shape of the fixing belt 61, and is installed with a gap of 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, for example, by winding litz wires made by bundling about 16 to 20 copper wires having a diameter of 0.5 mm that are insulated from each other in a closed loop shape such as an oval shape, an elliptical shape, or a rectangular shape. Use things. By applying an alternating current having a predetermined frequency to the exciting coil 851 by the exciting circuit 853, an alternating magnetic field H is generated around the exciting coil 851. When the AC magnetic field H crosses a metal layer of the fixing belt 61 described later, an eddy current I is generated so as to generate a magnetic field that hinders the change of the AC magnetic field H by electromagnetic induction. The frequency of the alternating current applied to the exciting coil 851 is set to 10 kHz to 50 kHz, for example. 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. Examples of such a non-magnetic 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 an electromagnetic induction heating member 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, a resistance heating element, and the like. The body 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 arrow D direction, 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 a pressing portion (nip portion N) with the pressure roll 62. The recording sheet P having the unfixed toner image provided on the surface thereof is carried into the fixing device 60 through the fixing inlet guide 56 by the conveying means. When the recording paper P passes through the pressing portion between 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 paper P. Thereafter, the recording paper P on which the image is formed is transported by the transport unit and discharged from the fixing device 60. In addition, the fixing belt 61 having finished the fixing process at the pressing portion and whose surface temperature on the outer peripheral surface has decreased rotates in the direction of the excitation coil 851 and is heated again in preparation for the next fixing process.

(Nip strain)
The Nip distortion of the fixing device 60 in the present embodiment will be described.
FIG. 3 is a diagram for explaining an example of the Nip distortion that the pressure pad 64 imparts to the fixing belt 61. In FIG. 3, only the fixing belt 61, the pressure pad 64, and the low friction sheet 68 in the fixing device 60 are shown.
The pressure pad 64 forms a concave portion in the region I and a convex portion in the region II. Therefore, in the region I, the pressure pad 64 generates a compressive stress (a tensile stress with respect to the inner surface 61 i) with respect to the outer surface 61 o of the fixing belt 61. In region II, a tensile stress (compressive stress with respect to the inner surface 61 i) is generated on the outer surface 61 o of the fixing belt 61. By forming the pressure pad 64 in such a shape, when the fixing belt 61 moves away from the surface of the pressure pad 64 on the pressure roll 62 side, a sudden change in curvature occurs, and the recording paper P after fixing is fixed to the fixing belt. It is easy to peel from 61.

Then, the strain due to the tensile stress received by the outer surface 61o of the fixing belt 61 in the region I and the strain due to the compressive stress received in the region II are added to obtain a Nip strain (a repeated strain width received by the fixing belt 61). For example, if the strain due to tensile stress is + and the strain due to compressive stress is −, the strain due to compressive stress is −0.3% in region I, and the strain due to tensile stress is + 0.5% in region II. The Nip strain is 0.8%.
The Nip distortion has been described as viewed from the outer surface 61o of the fixing belt 61, but may be viewed from the inner surface 61i of the fixing belt 61. Although the difference is that the compressive stress is the tensile stress and the tensile stress is the compressive stress, the Nip strain is the same.
In FIG. 3, the pressure pad 64 is formed with a concave portion and a convex portion so as to have both the compression stress region I and the tensile stress region II when viewed from the outer surface 61 o of the fixing belt 61. It is good also as a shape which generate | occur | produces.

(Fixing belt 61)
Next, the fixing belt 61 to which the exemplary embodiment is applied will be described.
FIG. 4 is a cross-sectional view showing an example of the configuration of the fixing belt 61 to which the exemplary embodiment is applied. As shown in FIG. 4, the fixing belt 61 has a long cylindrical shape having a three-layer structure in which a metal layer 61a, an elastic layer 61b, and a release layer 61c serving as a base material are provided in order from the inner peripheral side. . That is, the inner peripheral surface of the metal layer 61 a is the inner surface 61 i of the fixing belt 61, and the outer peripheral surface of the release layer 61 c is the outer surface 61 o of the fixing belt 61.
The metal layer 61a of the fixing belt 61 to which the present exemplary embodiment is applied is an endless (seamless) belt having seamless seams on the side surfaces. The fixing belt 61 to which this exemplary embodiment is applied is a metal belt.

FIG. 5 is a cross-sectional view showing in more detail an example of the configuration of the fixing belt 61 to which the exemplary embodiment is applied.
Here, the metal layer 61a has a multilayer structure of three layers. That is, the metal layer 61a having a multilayer structure includes a base metal layer 611, a heat generating metal layer 612, and an intermediate metal layer 613 from the inner peripheral side. In this embodiment, the base metal layer 611 and the intermediate metal layer 613 are chromium (Cr) 15 wt% or more and 19 wt% or less, nickel (Ni) 6 wt% or more and 10 wt% or less, manganese (Mn ) A stainless steel layer containing 1 wt% or more and 3 wt% or less and copper (Cu) 2 wt% or more and 5 wt% or less. Further, this stainless steel layer is composed of molybdenum (Mn) 0.2 wt% or less, silicon (Si) 0.5 wt% or less, phosphorus (P) 0.5 wt% or less, sulfur (S) 0.01 wt%. Hereinafter, carbon (C) is 0.1% by weight or less, and nitrogen (N) is 0.1% by weight or less. The balance is iron (Fe).
Table 1 shows the composition of the stainless steel layer used for the metal layer 61a in the present embodiment. In addition, about Fe, it is Bal. It shows.
The composition of 1% by weight or more is Cr, Ni, Mn and Cu excluding Fe. And 1 weight% or less of Mo, Si, P, S, C, and N are contained as impurities.

The exothermic metal layer 612 is, for example, a copper (Cu) layer.
The heat generating metal layer 612 generates heat by generating an eddy current due to the magnetic field generated by the exciting coil 851. The base metal layer 611 and the intermediate metal layer 613 protect the heat generating metal layer 612 with the heat generating metal layer 612 sandwiched therebetween, and, like the heat generating metal layer 612, an eddy current is generated by the magnetic field generated by the excitation coil 851. Fever.
The thickness of the metal layer 61a is preferably 5 μm to 100 μm. The thickness of the base metal layer 611 is preferably 5 μm to 40 μm, the thickness of the heat generating metal layer 612 is preferably 5 μm to 20 μm, and the thickness of the intermediate metal layer 613 is preferably 5 μm to 40 μm.

Here, the composition of the stainless steel layer in the metal layer 61a of the fixing belt 61 to which this exemplary embodiment is applied will be described.
When Cr is added in an amount of 15% by weight to 19% by weight, Cr is dissolved in Fe to form an Fe—Cr alloy, and the strength against fatigue fracture due to repeated bending deformation is improved by the effect of solid solution strengthening. If the amount of Cr added is excessively small, the effect of solid solution strengthening tends not to be sufficiently obtained. If it is excessively large, it tends to be too hard (work-hardened) by processing at the time of molding and become too brittle. is there.

  When 6 wt% to 10 wt% of Ni is added, Ni is dissolved in Fe to form an Fe—Ni alloy, and the strength against fatigue fracture due to repeated bending deformation is improved by the effect of solid solution strengthening. If the addition amount of Ni is excessively small, the effect of solid solution strengthening tends not to be sufficiently obtained. If it is excessively large, it tends to be too hard and brittle by being hardened (work hardening) by processing at the time of molding. .

  When Mn is added in an amount of 1 to 3% by weight, the degree of hardening at the time of plastic working by dissolving Mn in the Fe-Cr-Ni alloy to form an Fe-Cr-Ni-Mn alloy Can be mitigated, embrittlement due to work hardening can be prevented, and the strength against fatigue failure due to repeated bending deformation can be improved. If the amount of Mn added is excessively small, the effect of preventing embrittlement due to work hardening at the time of molding tends not to be obtained sufficiently. If the amount of Mn added is too large, it is hardened by processing (work hardening). It tends to be too hard and too brittle.

  On the other hand, when 2 to 5% by weight of Cu is added, cold workability is improved. In addition, when there is too little addition amount of Cu, the improvement of cold workability is not enough and it is easy to work harden | cure. If the amount of Cu added is excessively large, it tends to precipitate as an impurity at the crystal grain boundary and make the crystal grain boundary hard and brittle.

In the Fe—Cr—Ni alloy, if Mo is present in an amount of 0.2% by weight, Si is present in an amount of 0.5% by weight, P is present in an amount of more than 0.01% by weight, There is a tendency to precipitate at the grain boundaries and to make the grain boundaries hard and brittle.
Further, when C and N are present in the Fe—Cr—Ni alloy, C and N react with Fe to produce cementite, which is a hard and brittle compound, and tends to embrittle.

The work hardening coefficient (n value) of the stainless steel layer having the composition described in Table 1 was 0.4 or less. The power number n when the n-th power hardening formula is assumed to be established between the true strain and the true stress in the plastic region above the yield point is referred to as a work hardening coefficient (n value).
The greater the work hardening coefficient, the greater the elongation and the easier it is to draw. However, if the residual strain increases due to work hardening at the time of molding, fatigue failure is likely to occur.

Next, the elastic layer 61b and the release layer 61c will be described.
The elastic layer 61b is made of a material that can obtain elasticity and heat resistance. For example, known heat resistant rubbers such as silicone rubber and fluorine rubber can be used. Among these, silicone rubber is preferable because it has a low surface tension and is excellent in elasticity. Examples of such silicone rubber include RTV silicone rubber and HTV silicone rubber. Specifically, MQ (polydimethyl silicone rubber), VMQ (methyl vinyl silicone rubber), PMQ (methyl phenyl silicone rubber). , FVMQ (fluorosilicone rubber) and the like.
The thickness of the elastic layer 61b is usually 50 μm to 400 μm, preferably 100 μm to 300 μm. The rubber hardness of the elastic layer 61b is 10 ° to 50 °, preferably 20 ° to 40 °, as defined by Asker C.

The release layer 61c is made of a material that exhibits an appropriate release property for the toner image. Examples thereof include fluororesins such as fluororubber, PTFE (polytetrafluoroethylene), PFA, and FEP (tetrafluoroethylene hexafluoropropylene copolymer), silicone resins, and polyimide resins.
The thickness of the release layer 61b is usually 10 μm to 50 μm, preferably 20 μm to 40 μm.

Now, a method for manufacturing the fixing belt 61 will be described.
First, heat treatment is performed on a stainless steel plate (for example, thickness 0.2 mm) in a nitrogen atmosphere at 1,100 ° C., for example. Then, the bonded surfaces of the two stainless steel plates and the copper plate (for example, thickness 0.1 mm) are polished to remove the oxide film formed on the surfaces. Thereafter, a copper plate is sandwiched between two stainless steel plates, and rolling is performed in a cold state (a temperature lower than the recrystallization temperature). Thereby, a clad steel plate (thickness of three layers is 0.4 mm, for example) is obtained in which the copper layer is sandwiched between two stainless steel layers. Then, the clad steel sheet is subjected to heat treatment, for example, under a nitrogen atmosphere, for example, at a processing temperature of 900 ° C. and a processing time of 60 minutes.

Next, the clad steel plate is formed into a cylindrical shape by a deep drawing method, a spatula drawing method, a pressing method or the like. Thereafter, it is molded into a cylindrical shape having an opening and a bottom by rotary plastic processing (spindle processing). Then, the opening and the bottom are cut and removed to obtain an endless belt (seamless belt).
Thereafter, the elastic layer 61b is formed on the metal layer 61a by a ring coating method, a dip coating method, an injection molding method, or the like. Further, the release layer 61c is formed on the elastic layer 61c by an electrostatic powder coating method, a spray coating method, a dip coating method, a centrifugal film forming method, or the like.
Thus, the fixing belt 61 is manufactured.

  Hereinafter, the present invention will be described more specifically based on examples and comparative examples. In addition, this invention is not limited to a following example, unless the summary is exceeded.

(1. Production of fixing belt 61)
In the fixing belts 61 of Examples 1 to 10 and Comparative Examples 1 to 7, the metal layer 61a having a multilayer structure shown in FIG. 4 was used. In Comparative Example 8, a single metal layer 61a (nickel electroformed belt) formed by electroforming nickel on the fixing belt 61 was used.
Table 2 is a table | surface which shows the composition of the stainless steel layer used for the base metal layer 611 and the intermediate | middle metal layer 613 of the metal layer 61a of a multilayer structure. The base metal layer 611 and the intermediate metal layer 613 are stainless steel layers having the same composition.
The stainless steel used for the fixing belt 61 is charged by measuring each constituent element based on a predetermined composition at the time of manufacture (melting / casting). However, the compositions shown in Table 2 were sampled from a melted / cast / rolled stainless steel material and determined by elemental quantitative analysis (atomic absorption or inductively coupled plasma (ICP) analysis).

In Table 2, as the composition of the stainless steel layer, chromium (Cr), nickel (Ni), manganese (Mn), copper (Cu), molybdenum (Mo), silicon (Si), phosphorus (P), sulfur (S) Carbon (C) and nitrogen (N) are expressed in weight%. And about iron (Fe), it represents as residual amount (Bal.).
In addition, about the comparative example 8, only the nickel electroforming belt is represented. The nickel (Ni) of the nickel electroformed belt of Comparative Example 8 has a purity of 99.99%.

Here, a method for manufacturing the fixing belt 61 will be described.
First, the metal layer 61a having a multilayer structure used for the fixing belt 61 of Examples 1 to 10 and Comparative Examples 1 to 7 will be described.
First, a stainless steel plate having a composition shown in Table 2 (thickness: 0.2 mm) is sandwiched between copper plates, rolled in a cold state, and a clad steel plate (three layers in which the copper layer is sandwiched between two stainless steel layers). Of 0.4 mm) was obtained.

  Then, the clad steel plate was formed into a cylindrical container shape having a depth of about 10 mm by pressing and deep drawing. Then, it was molded into a cylindrical shape having an opening and a bottom by rotary plastic processing (spindle processing). Then, the opening and the bottom were cut and removed to obtain an endless belt (seamless belt) having an inner diameter of 30 mm, a length of 370 mm, and a wall thickness of 50 μm. In the endless belt, the thickness of the base metal layer 611 of the stainless steel layer is 20 μm, the thickness of the heat generating metal layer 612 of Cu is 10 μm, and the thickness of the intermediate metal layer 613 of the stainless steel layer is 20 μm.

In the base metal layer 611 and the intermediate metal layer 613 that are stainless steel layers, strain is accumulated due to the stress applied by the press / deep drawing process and the rotary plastic process.
Note that Cu used for the heat generating metal layer 612 has high malleability, and therefore, accumulation of strain is less than that of the base metal layer 611 and the intermediate metal layer 613 which are stainless steel layers.

Next, a method for producing the metal layer 61a of the nickel electroformed belt used for the fixing belt 61 of Comparative Example 8 will be described. The metal layer 61a is produced by immersing a cylindrical stainless steel mold having an outer diameter of 30 mm in an electrolytic plating bath containing nickel sulfate as a main component and having a pH of 3.0 and a bath temperature of 50 ° C., and a cathode current density of 7 A / dm. Electrodeposition was performed at ² for 60 minutes. As a result, a metal layer 61a having an inner diameter of 30 mm, a film thickness of 50 μm, and a length of 370 mm was obtained.

Here, a method for manufacturing the elastic layer 61b and the release layer 61c will be described.
Liquid silicone rubber (KE1940-35, liquid silicone rubber 35 ° product, manufactured by Shin-Etsu Chemical Co., Ltd.) adjusted so that the hardness defined by Asker C is 35 ° on the outer surface of the metal layer 61a, The film was applied to a thickness of 200 μm and dried to obtain a dry liquid silicone rubber layer.
A PFA dispersion (500 CL, manufactured by Mitsui DuPont Fluoro Chemical Co., Ltd.) was applied to the surface of the dried liquid silicone rubber layer so as to have a film thickness of 30 μm and baked at 380 ° C.
Thus, an elastic layer 61b made of silicone rubber and a release layer 61c made of PFA were produced.
Thus, the fixing belt 61 was obtained.

(2. Production of pressure roll 62)
A fluororesin tube (becomes the surface layer 623) having an outer diameter of 50 mm, a length of 340 mm, and a thickness of 30 μm with an adhesive primer applied to the inner surface and a metal core 621 are set in a molding die. Then, liquid foamed silicone rubber (which becomes the rubber layer 622) is injected between the fluororesin tube and the core 621. Then, by performing heat treatment (150 ° C., 2 hours), the silicone rubber is vulcanized and foamed to produce a pressure roll 62 having rubber elasticity. The layer thickness of the rubber layer 622 is 2 mm.

(3. Electromagnetic induction heat generation idling durability evaluation)
The produced fixing belt 61 and pressure roll 62 were attached to an image forming apparatus 100 (Fuji Xerox Co., Ltd., Docu Print C620) provided with the fixing device 60 shown in FIG.
In this image forming apparatus 100, the fixing belt 61 was idled for 200 hours continuously (idle rotation for 200 hours) while heating the fixing belt 61 by electromagnetic induction heating as described above. Then, the heat generation maintainability (reliability) of the fixing belt 61 and the presence or absence of cracks generated in the metal layer 61a of the fixing belt 61 were evaluated. The idling means that the fixing belt 61 is pressed against the pressure roll 62 and the pressure roll 62 is rotated without fixing the toner onto the recording paper P.

(4. Nip distortion)
The Nip distortion applied to the fixing belt 61 by the pressure pad 64 was set to be 0.7% or more (see Table 2).
Specifically, a strain gauge (for example, KFEL-2-120-C1L1M2R manufactured by Kyowa Denki Co., Ltd.) is attached to the surface of the metal layer 61a, and the strain given by the nip (N) with the pressure pad 64 is applied. It was measured.
If the Nip strain does not reach a predetermined value (here, 0.7%), the pressure pad 64 is changed to change the Nip strain to a predetermined value (here, 0.7%). ) The above cases were regarded as examples and comparative examples.
The fixing belt 61 is repeatedly subjected to distortion (Nip distortion) due to bending deformation every time it rotates. Therefore, the larger the Nip strain, the more the strain accumulates on the fixing belt 61, particularly the metal layer 61a, and the fatigue failure tends to occur.
Note that a Nip strain of 0.7% or more is a large value as the amount of strain repeatedly applied each time it rotates.

(5. Heat generation characteristics)
The fixing belt 61 is set to 180 ° C. at the start time (initial state) of the electromagnetic induction heat generation idling durability evaluation. The fixing belt 61 is operated so as to maintain this temperature. However, if the base metal layer 611 or the intermediate metal layer 613 of the stainless steel layer of the metal layer 61a is cracked, the heat-generating metal layer 612 of Cu is also cracked, and the eddy current hardly flows. For this reason, the temperature of the fixing belt 61 is not maintained, and the temperature of the fixing belt 61 decreases (heat generation failure). Therefore, the heat generation state of the fixing belt 61, that is, the heat generation maintaining characteristic (reliability) was evaluated based on the temperature of the fixing belt 61.
The temperature of the fixing belt 61 was monitored with an infrared thermometer.

(6. Cracks)
On the other hand, the occurrence of cracks was determined by sound generation and visual observation. In many cases, it makes a sound when cracks occur. When a sound is made, a crack having a width of 0.1 mm and a length of about 10 mm is seen on the outer peripheral surface 61o of the metal layer 61a. Therefore, the presence or absence of cracks was determined visually. In addition, even in the case where no sound was generated in the continuous idling for 200 hours, the surface of the metal layer 61a was observed after 200 hours to determine the presence or absence of cracks.

(Examples 1-10, Comparative Examples 1-8)
Table 2 shows the result of the electromagnetic induction heat generation idling durability evaluation using the produced fixing belt 61.

From the results shown in Table 2, the fixing belt 61 (Examples 1 to 10) using the stainless steel layer having the composition range included in Table 1 has an initial heat generation characteristic (180 ° C.) in idling continuously for 200 hours. Maintained. Further, no cracks were found in the metal layer 61a of the fixing belt 61 after idling for 200 hours continuously.
Further, in the fixing belt 61 of Example 9 in which Cr and Mn were the upper limit of the range, even when the Nip distortion was 1.2%, no heat generation failure and cracks occurred during continuous 200-hour idling.
On the other hand, the fixing belt 61 (Comparative Examples 1 to 7) using the stainless steel layer having a composition out of the composition range shown in Table 1 has a poor heat generation between 20 hours and 44 hours from the start of continuous 200 hours idling. Thus, cracks were found in the metal layer 61a.

  Further, in the fixing belt 61 using the nickel electroformed belt (Comparative Example 8), a heat generation failure occurred in only 6 hours from the start of idling for 200 hours continuously, and cracks were found in the Ni metal layer 61a. It was. This is considered to be due to fatigue failure in a short time because the bending deformation (Nip strain) repeatedly applied during use is as large as 0.7% or more (actually 1.0%). That is, it is considered that the nickel electroformed belt is difficult to use for the fixing device 60 that has a large bending deformation (Nip distortion) repeatedly applied during use.

  On the other hand, even with the fixing belt 61 (Comparative Examples 1 to 7) using a stainless steel layer as the metal layer 61a, a heat generation failure occurs and cracks occur between 20 hours and 41 hours from the start of continuous 200 hours idling. Was found.

  The difference between the fixing belt 61 in Examples 1 to 10 in which heat generation failure and cracks do not occur and the fixing belt 61 in Comparative Examples 1 to 7 in which heat generation failure and cracks occur are the same for the metal layer 61a. The difference is in the composition of the stainless steel layer.

Austenitic stainless steel containing Cr and Ni has a high work hardening coefficient and is easily hardened (work hardened) by cold working. For this reason, it is said that austenitic stainless steel is suitable for drawing. On the other hand, in cold working, strain (residual strain) is likely to accumulate, and if strain due to repeated deformation is applied during use, it is considered that fatigue fracture is likely to occur.
The stainless steel layer used for the metal layer 61a of the fixing belt 61 of Examples 1 to 10 and Comparative Examples 1 to 7 is also included in the austenitic stainless steel.

  Therefore, it is considered that the stainless steel layers (Comparative Examples 1 to 7) having a composition outside the range shown in Table 1 are hard and too brittle due to work hardening, or have low fatigue strength against repeated bending deformation. For this reason, it seems that fatigue failure was reached in a short time.

  As described above, the fixing belt 61 using the stainless steel layer included in the range shown in Table 1 as the metal layer 61a according to the present embodiment can reduce heat generation defects and cracks.

  In the present embodiment, a metal layer 61a having a three-layer structure is used as the metal layer 61a. However, the metal layer 61a may have a single-layer structure made of a stainless steel layer or a two-layer structure of a stainless steel layer and a copper layer.

1Y, 1M, 1C, 1K ... image forming unit, 11 ... photosensitive drum, 12 ... charger, 13 ... laser exposure device, 14 ... developing device, 15 ... intermediate transfer belt, 16 ... primary transfer roll, 17 ... drum cleaner , 20 ... secondary transfer section, 60 ... fixing device, 61 ... fixing belt, 61a ... metal layer, 61b ... elastic layer, 61c ... release layer, 62 ... pressure roll, 63 ... belt guide member, 64 ... pressure pad , 65 ... Holder, 67 ... Lubricant application member, 68 ... Low friction sheet, 70 ... Peeling auxiliary member, 71 ... Peeling baffle, 85 ... Magnetic field generating unit, 100 ... Image forming device, 621 ... Core, 622 ... Rubber layer, 623 ... Surface layer, 851 ... Excitation coil, 852 ... Coil support member, 853 ... Excitation circuit

Claims (9)

A stainless steel layer containing at least 15% by weight and 19% by weight or less of chromium, 6% by weight or more and 10% by weight or less of nickel, 1% by weight or more and 3% by weight or less of manganese, 2% by weight or more and 5% by weight or less of copper A cylindrical metal layer having one layer;
A release layer laminated outside the metal layer;
An endless belt comprising:   The endless belt according to claim 1, wherein the metal layer includes a plurality of the stainless steel layers and a copper layer sandwiched between the stainless steel layers.   The endless belt according to claim 1 or 2, wherein the stainless steel layer of the metal layer has a carbon content of 0.1 wt% or less.   The endless belt according to any one of claims 1 to 3, wherein the stainless steel layer of the metal layer has a work hardening coefficient of 0.4 or less.   The endless belt according to any one of claims 1 to 4, further comprising an elastic layer between the metal layer and the release layer. A stainless steel layer containing at least 15% by weight and 19% by weight or less of chromium, 6% by weight or more and 10% by weight or less of nickel, 1% by weight or more and 3% by weight or less of manganese, 2% by weight or more and 5% by weight or less of copper A fixing belt comprising a cylindrical metal layer having one layer, and a release layer laminated on the outside of the metal layer;
A pressure member pressed against the outside of the fixing belt;
A heating member provided inside the fixing belt for heating the fixing belt;
A fixing device comprising:   The fixing device according to claim 6, wherein a repetitive strain width received by the fixing belt is 0.7% or more.   The fixing device according to claim 6, wherein the heating member is an electromagnetic induction heating member that generates an eddy current in the metal layer of the fixing belt to generate heat. An image forming unit for forming a toner image;
A transfer unit that transfers the toner image formed in the image forming unit to a recording material;
A stainless steel layer containing at least 15% by weight and 19% by weight or less of chromium, 6% by weight or more and 10% by weight or less of nickel, 1% by weight or more and 3% by weight or less of manganese, 2% by weight or more and 5% by weight or less of copper A fixing belt comprising a cylindrical metal layer having one layer and a release layer laminated on the outside of the metal layer; and a pressure member that is rotationally driven by forming a pressing portion between the fixing belt; A fixing unit that is provided inside the fixing belt and has a heating member that heats the fixing belt, and fixes the toner image transferred to the recording material to the recording material;
An image forming apparatus comprising:

Images