JP2004233970A - Belt for image forming apparatus and its manufacturing method and image forming apparatus using the belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for an anchoring belt capable of suppressing irregularities in pressure caused by the anchoring belt for maintaining a recording quality. <P>SOLUTION: A mold release layer 2 containing a fluororesin is applied onto a molding surface 1a of a molding die 1 for baking. An elastic layer 3 is applied to the outside of the mold release layer for baking. A support layer 4 containing a heat-resistant synthetic resin is applied to the outside of the elastic layer for drying. The dried support layer is polished for removing the irregularities to bake the support layer. The front and rear are reversed from the mold release, elastic, and support layers and the molding surface for performing mold release. Planarity in the anchoring belt is increased for suppressing the irregularities in pressure. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a belt (for example, a fixing belt, a transfer belt, and the like) used in an image forming apparatus and a related technique. The fixing belt is used in an image forming apparatus such as a copying machine, a facsimile, and a printer that employs an electrophotographic method, and is used for a fixing unit that heats and fixes a toner image on a recording medium. It is used in a transfer section for transferring a toner image formed on a body to a recording medium.

  Hereinafter, a fixing belt will be described as a belt for an image forming apparatus. As a fixing method, a heat fixing method, particularly, a heat roller fixing method has been widely used.

  In the heat roller fixing method, a pair of rollers consisting of a heat roller and a rubber roller are pressed against each other. Then, by passing the recording medium on which the toner image is formed between the pair of rollers, the toner on the recording medium is heated and melted, and the toner is fused on the recording medium. In the heat roller fixing method, since the entire heat roller is maintained at a predetermined temperature, it is suitable for speeding up, but on the other hand, the waiting time is long.

  Therefore, in recent years, an endless belt fixing method has been proposed. In this method, a toner on a recording medium is heated via a film-shaped endless belt. In this fixing method, the temperature of the heat roller or the like reaches a predetermined temperature in a short time, the waiting time when the power is turned on becomes almost zero, and the power consumption is small.

As disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-202675), a fixing belt used in this fixing method is, in order, from the outer layer side.
(1) a release layer containing a fluororesin (eg, ethylene tetrafluoride polymer (PTFE) or the like) and located at the outermost layer;
(2) an elastic layer (for example, silicone rubber or the like) located between the release layer and the support layer; and (3) a heat-resistant synthetic resin (for example, polyimide (PI) or the like). It is preferable that the supporting layers are formed respectively.

  If this fixing belt is used, a plurality of color toners (for example, four colors) can be melted, and this fixing belt can be used also in a fixing unit in a full-color image forming apparatus. is there.

  A desired adhesive layer is usually provided between the release layer and the elastic layer, and between the elastic layer and the support layer. However, since these adhesive layers are not related to the gist of the present invention, In this specification, reference to an adhesive layer is omitted unless otherwise required.

  Next, a method of manufacturing this type of fixing belt according to a conventional technique and its problems will be described with reference to FIGS.

  First, as shown in FIG. 12A, a molding die 1 having a molding surface 1a and having a predetermined shape is prepared. In FIG. 10, the molding surface 1a is illustrated as a plane, but this is for the purpose of making the illustrated result easier to understand, and the molding surface 1a is usually a cylindrical surface.

  Next, as shown in FIG. 12 (b), a release layer 2 containing a fluororesin is applied on the molding surface 1a and baked.

  Next, as shown in FIG. 12C, the elastic layer 3 is applied to the outside of the release layer 2 (on the side opposite to the molding surface 1a when viewed from the release layer 2), and is fired.

Further, as shown in FIG. 12D, a support layer 4 is applied to the outside of the elastic layer 3 (the side opposite to the molding surface 1a when viewed from the elastic layer 3), and the support layer 4 is fired.
JP-A-2002-202675 (pages 2-5)

  However, when the support layer 4 is applied, the thickness of the support layer 4 often varies, as in the thin portion 4a and the thick portion 4b shown in FIG.

  If the support layer 4 is baked in the presence of this variation, the following phenomenon is caused.

  That is, when heating is performed to bake the support layer 4, in the support layer 4 containing, for example, polyimide (PI), imidization proceeds and curing starts. In this baking process, the polyimide shrinks, and the shrinkage is larger in the thick portion 4b than in the thin portion 4a.

  In addition, since the elastic layer 3 adjacent to the support layer 4 can be elastically deformed, different amounts of deformation occur in the elastic layer 3 in the portion in contact with the thick portion 4b and in the portion in contact with the thin portion 4a.

  As a result, after the support layer 4 is fired, as shown in FIG. 12E, irregularities are formed on both surfaces of the support layer 4 of the fixing belt 5.

  In this case, as shown in FIG. 13, the recording medium (for example, recording paper) 9 onto which the toner 8 has been transferred and the fixing belt 5 are sandwiched between the fixing roller 6 and the pressure roller 7 in the nip portion. At this time, the pressure acting on the recording medium 9 may be uneven depending on the location (whether the concave portion or the convex portion of the support layer 4), and the recording quality may be degraded.

  Therefore, an object of the present invention is to provide a method of manufacturing a belt for an image forming apparatus capable of suppressing a decrease in recording quality, and a related technique thereof.

  The method for manufacturing a belt for an image forming apparatus according to claim 1, wherein a step of applying a release layer containing a fluororesin to a molding surface of the mold, a step of firing the applied release layer, and a step of: A step of applying an elastic layer on the side opposite to the molding surface when viewed, a step of firing the applied elastic layer, and a support layer containing a heat-resistant synthetic resin on the side opposite to the molding surface as viewed from the elastic layer. The method includes a step of applying, a step of firing the applied support layer, a step of removing irregularities of the fired support layer, and a step of releasing the release layer, the elastic layer, and the support layer from the molding surface.

  In this configuration, by removing the unevenness of the baked support layer, the surface of the support layer opposite to the molding surface becomes flat, the pressure unevenness due to the belt is suppressed, and the recording quality can be improved. When applied to a fixing belt, pressure unevenness due to the fixing belt is suppressed, and recording quality can be improved.

  The method for manufacturing a belt for an image forming apparatus according to claim 2, wherein a step of applying a release layer containing a fluororesin to a molding surface of the mold, a step of firing the applied release layer, and a step of: A step of applying an elastic layer on the side opposite to the molding surface when viewed, a step of firing the applied elastic layer, and a support layer containing a heat-resistant synthetic resin on the side opposite to the molding surface as viewed from the elastic layer. A step of applying, a step of drying the applied support layer, a step of removing unevenness of the dried support layer, a step of firing the support layer, a release layer, an elastic layer and a support layer, and Releasing the mold.

  In this configuration, by removing the unevenness of the dried support layer, the surface of the support layer opposite to the molding surface becomes flat, the pressure unevenness due to the belt is suppressed, and the recording quality can be improved. When applied to a fixing belt, pressure unevenness due to the fixing belt is suppressed, and recording quality can be improved.

  In addition, since the unevenness of the support layer is removed before the imidization of the support layer proceeds, the unevenness of the elastic deformation of the elastic layer is suppressed, and the flatness of the belt is further ensured.

  Here, in the conventional technique, a silicone rubber layer (heat resistance temperature of about 250 ° C.) is formed as an elastic layer on the outer surface of a polyimide tube as a support layer, and a fluororesin is applied as a release layer on the outer surface of the elastic layer. There was a configuration. However, because of the low heat resistance of the silicone rubber layer, the sintering temperature of the fluororesin could not be set to about 380 ° C. or more required for sintering.

  On the other hand, in the configuration according to the first or second aspect, the elastic layer is formed by following the reverse of the conventional technique, that is, forming the elastic layer after applying and releasing the release layer on the mold. As in the technique, when the release layer is fired, the elastic layer is not hardened by heat. Further, since the molding surface is in contact with the release layer, superior planar smoothness can be obtained as compared with the release layer formed on the free molding surface.

  In the method of manufacturing a belt for an image forming apparatus according to the third aspect, the unevenness of the support layer is removed by polishing the support layer.

  With this configuration, the unevenness of the support layer can be easily removed without hindering the steps of applying and firing each layer.

  In the method of manufacturing a belt for an image forming apparatus according to claim 4, the release layer, the elastic layer, and the support layer, and the release from the molding surface, and simultaneously or after, the release layer, the elastic layer, and the support layer. Is integrated.

  Here, by inverting the surface in this way, there is an effect of reducing uneven wrinkles of the release layer. In other words, the release layer is initially formed on the molding surface side of the support layer, but when it is turned over, the release layer is pulled in the circumferential direction, so that the uneven wrinkles of the release layer are reduced. .

  6. The method for manufacturing a belt for an image forming apparatus according to claim 5, wherein the fluororesin is ethylene tetrafluoride polymer (PTFE), ethylene tetrafluoride-perfluoroalkoxy ethylene copolymer (PFA), and ethylene fluoride-propylene. One or more selected from the group consisting of copolymers (PFEP).

  With this configuration, the releasability of the toner is favorably maintained.

  In the method for manufacturing a belt for an image forming apparatus according to the sixth aspect, the heat-resistant synthetic resin is one or two or more selected from the group consisting of polyimide (PI) and polyamideimide (PAI).

  With this configuration, a support layer having excellent strength, heat resistance, cost performance, and the like can be formed.

  The image forming apparatus according to claim 16, further comprising: a first image carrier for holding an image formed of toner; and a transfer belt on which the image formed on the first image carrier is transferred. The belt contains a fluororesin, and a release layer located at the outermost layer, a heat-resistant resin, a support layer located at the innermost layer, and an elastic layer located between the release layer and the support layer. A support layer, wherein at least one of the baked support layer and the dried support layer is formed by removing irregularities.

  With this configuration, the flatness of the transfer belt is ensured, and pressure unevenness can be suppressed.

  The image forming apparatus according to a seventeenth aspect further includes a plurality of rollers around which the transfer belt is wound, and the surface roughness of the support layer from which the unevenness is removed is smaller than the surface roughness of the plurality of rollers.

  With this configuration, the contact between the transfer belt and the plurality of rollers over which the transfer belt is stretched is further increased, and the rotation speed fluctuation due to the unevenness of the transfer belt is suppressed, and the color superposition is stabilized, and a good image is obtained. Can be

  20. The image forming apparatus according to claim 18, further comprising: a first image carrier that holds an image formed of toner; and a transfer belt onto which the image formed on the first image carrier is transferred. The belt contains a fluororesin, and a release layer located at the outermost layer, a heat-resistant resin, a support layer located at the innermost layer, and an elastic layer located between the release layer and the support layer. A release layer, wherein the linear thermal expansion coefficient of the release layer is greater than the linear thermal expansion coefficient of the support layer.

  With this configuration, it is possible to cope with the difference in the circumferential length generated in the order of forming the layers and the expansion and contraction when the support layer and the release layer are used upside down, so that wrinkles appearing in the release layer are reduced, and the toner is removed. The performance can be improved, and the rotation speed fluctuation caused by the surface unevenness can be suppressed to stabilize the color superposition, thereby improving the recording quality.

  In the image forming apparatus according to the nineteenth aspect, the support layer is formed by removing at least one of a baked support layer and a dried support layer.

  In this configuration, by removing the unevenness of the support layer, the surface of the support layer opposite to the molding surface becomes flat, the pressure unevenness due to the belt is suppressed, and the recording quality can be improved.

  The image forming apparatus according to the twentieth aspect further includes a cleaning unit that removes toner remaining on the transfer belt, and the cleaning unit includes an elastic blade unit.

  According to this configuration, it is possible to cope with a difference in circumference that occurs in the order in which the layers of the transfer belt are formed, expansion and contraction when the support layer and the release layer are used upside down, and wrinkles appearing in the release layer can be suppressed.

  By the way, when the transfer belt is released from the mold, the lowermost layer is the release layer, and the uppermost layer is the support layer. Further, the coefficient of linear thermal expansion of the release layer is larger in the release layer than in the support layer, and wrinkles are easily formed on the surface (the lowermost layer) of the release layer. When the transfer belt after release is turned upside down, the release layer located at the lowermost layer becomes the uppermost layer. That is, after the reversal, the inner diameter of the release layer becomes smaller than the inner diameter of the support layer, the surface of the release layer extends, and even if wrinkles are generated on the surface of the release layer, the wrinkles disappear and the surface becomes Becomes flatter.

  Further, when removing the toner remaining on the surface of the transfer belt, it is effective to press the elastic blade means to remove the toner from the surface of the transfer belt.

  Here, in addition to the toner particles at the center, a plurality of external additives that suppress aggregation of the toner and control charging are often used, and the external additives are usually considerably smaller than the toner particles. . Considering this point, when removing the toner and the external additive on the transfer belt by the blade means, the blade means is considerably bite into the transfer belt, and the edge of the blade means and the surface layer of the transfer belt are in close contact. It is desirable to do. It is also effective to remove the unevenness of the support layer to make the cleaning surface of the transfer belt flat to improve the cleaning performance.

  The image forming apparatus according to the twenty-first aspect further includes a support unit that supports the cleaning unit, and the transfer belt is sandwiched between the cleaning unit and the support unit.

  With this configuration, the toner and external additives on the transfer belt can be effectively removed by using the transfer belt and the blade means in which wrinkles are suppressed. Furthermore, by sandwiching the transfer belt between the blade means and the support means, the blade means and the surface layer of the transfer belt are more closely adhered to each other, and the performance of removing toner and external additives is improved. In this case, the surface layer of the transfer belt and the support layer should have as few irregularities as possible.

  ADVANTAGE OF THE INVENTION According to this invention, the unevenness | corrugation of a baked support layer is removed, the flatness of a belt is improved, pressure unevenness can be suppressed, and recording quality can be improved.

  In addition, before the imidization of the support layer progresses, unevenness of the support layer is removed, thereby making it possible to suppress uneven elastic deformation of the elastic layer.

  Further, the belt can be turned upside down to suppress the generation of wrinkles in the release layer. For example, the fixing belt can be turned upside down to suppress the generation of wrinkles in the release layer.

  Further, according to the present invention, the unevenness of the baked support layer is removed, the flatness of the belt is improved, good image formation can be performed, and the performance of removing toner adhering to the surface is enhanced. Thus, a belt that can exhibit stable performance can be obtained.

  Further, before the imidization reaction of the support layer proceeds, the unevenness of the support layer is removed, the elastic deformation of the elastic layer can be suppressed, and the flatness of the belt can be further improved.

  In addition, by making the coefficient of linear thermal expansion of the release layer larger than the coefficient of linear thermal expansion of the support layer, when the transfer belt is used upside down, the occurrence of surface wrinkles is suppressed, and a flatter surface is obtained. .

  Further, by using blade means for removing the toner remaining on the surface of the belt, the toner can be more reliably removed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of an image forming apparatus according to an embodiment of the present invention. In the drawings, the same components as those in FIGS. 12 and 13 showing the related art are denoted by the same reference numerals, and description thereof will be omitted.

  As shown in FIG. 1, the image forming apparatus 10 employs an electrophotographic system, and more specifically, employs a tandem system. However, the present invention is not limited to a tandem-type image forming apparatus, and can be applied to various image forming apparatuses regardless of the number of developing units, the presence or absence of a transfer belt, and the like.

  The transfer belt 11 formed endlessly is wound around a drive roller 12 and a tension roller 13 and holds a visualized toner image. Then, when the drive roller 12 and the tension roller 13 rotate in the direction of arrow A, the transfer belt 11 moves in the direction of arrow N1.

  On the upper side of the transfer belt 11, on the transfer belt 11, an image forming unit 28 for forming a black image, an image forming unit 29 for forming a cyan image, an image forming unit 30 for forming a magenta image, and an image for forming a yellow image The forming parts 31 are arranged in this order.

  Since these image forming units 28 to 30 differ only in the color of the image to be formed, the image forming unit 28 that forms a black image will be mainly described below.

  The charging section 33 of the image forming section 28 uniformly charges the peripheral surface of the photosensitive drum 32 to a predetermined potential.

  The exposure unit 23 irradiates a scanning line 24 of a laser beam onto the peripheral surface of the photosensitive drum 32, and forms a latent image related to a black component on the peripheral surface of the photosensitive drum 32. Similarly, with respect to the image forming units 29 to 30 of other colors, the exposure unit 23 irradiates the photosensitive drums with the scanning lines 25 to 27 to form latent images related to the color components.

  The developing unit 34 visualizes the latent image formed on the peripheral surface of the photosensitive drum 32. The transfer unit 35 transfers the visualized toner image on the peripheral surface of the photoconductor drum 32 to the transfer belt 11.

  The cleaner 36 removes residual toner remaining on the peripheral surface of the photosensitive drum 32 after the transfer of the toner image to the transfer belt 11.

  Further, toner images of cyan, magenta, and yellow components are sequentially transferred to the transfer belt 11 by the image forming units 28 to 31, and the four color components are superimposed on the transfer belt 11 to form a full-color toner. An image is formed on the transfer belt 11.

  The recording medium 9 such as recording paper is stored in a paper feed cassette 16, and is fed out one by one to a transport path 18 by a paper feed roller 17.

  The transfer roller 14 faces the drive roller 12, and the recording medium 9 that travels along the transport path 18 is sandwiched between the drive roller 12 and the transfer roller 14 and pressed against the transfer belt 11, so that the recording medium 9 , A full-color toner image is collectively transferred.

  After the batch transfer, the recording medium 9 advances along the transport path 18 and passes through the nip 22 of the fixing unit 19. During this passage, the full-color toner image (unfixed), which is collectively transferred to the recording medium 9, is melted by being sandwiched between the high-temperature fixing roller 6 and the pressure roller 7 in the nip portion 22. It is pressed and fixed to the recording medium 9.

  Next, the fixing unit 19 will be described with reference to FIG. FIG. 2 is a sectional view of the fixing unit according to the embodiment of the present invention.

  First, as shown in FIG. 2, the pressure roller 7 is made of a metal having high heat conductivity (for example, stainless steel, aluminum, or the like) and covers a cylindrical core 7 a and a peripheral surface of the core 7 a. And an elastic portion 7b. The elastic portion 7b is made of a material having excellent heat resistance and toner releasability.

  The pressure roller 7 presses the fixing roller 6 via the fixing belt 5 at the nip portion 22.

  In this embodiment, the outer diameter of the pressure roller 7 is about 30 mm, which is the same as that of the fixing roller 6, and the thickness of the pressure roller 7 is about 2 to 5 mm, which is thinner than that of the fixing roller 6. The hardness of the fixing roller 6 is set to be about 20 to 80 degrees (Asker C) so as to be harder than that of the fixing roller 6.

  This makes it possible to increase the toner peeling action at the outlet of the nip 22.

  The heating roller 39 is formed by forming a magnetic metal member (for example, stainless steel or the like) into a hollow cylindrical shape (outer diameter: for example, 20 mm, wall thickness: for example, 0.3 mm). The heat capacity of the heating roller 39 is set low, so that the temperature of the heating roller 39 quickly rises.

  The fixing roller 6 includes a cylindrical metal core 6a made of metal (for example, stainless steel) and an elastic portion 6b that covers the periphery of the metal core 6a. The elastic portion 6b is formed by solidifying or foaming silicone rubber having heat resistance.

  In this embodiment, the outer diameter of the fixing roller 6 is about 30 mm, the same as that of the heating roller 39, the thickness of the elastic part 6 b is about 3 to 8 mm, and the hardness of the elastic part 6 b is 15 to 50 degrees (Asker C). Therefore, a contact portion having a predetermined width is formed between the fixing roller 6 and the pressure roller 7 at the nip portion 22 by the pressing force from the pressure roller 7.

  The pressure roller 39 is heated by the induction heating unit 44, as will be described in detail later. The fixing belt 5 is stretched around the heating roller 39 and the fixing roller 6 and is in circumferential contact with the pressure roller 39.

  Therefore, when the fixing roller 6 is rotated by a driving unit (not shown), the fixing belt 5 rotates in the direction of the arrow N2, and the inner surface of the fixing belt 5 is continuously and entirely heated. .

  Next, the induction heating unit 44 has the following elements. First, the guide plate 40 is formed in a semicircular shape so as to surround the outer periphery of the heating roller 39, and is arranged close to the heating roller 39.

  The excitation coil 41 is formed by winding a single long excitation coil wire along the guide plate 40 so as to face the axial direction of the heating roller 39. The winding length is determined by the fixing belt 5 and the heating roller 39. Is the same as the length of the area in contact.

  In this way, the induction heating unit 44 efficiently heats the heating roller 39 by electromagnetic induction, and the time during which the surface of the heating roller 39 that is generating heat and the fixing belt 5 are in contact is maximized, so that the heat transfer efficiency is increased. .

  The excitation coil 41 is connected to a drive power supply (not shown) whose oscillation circuit is variable in frequency and is excited.

  A core 42 in which a ferromagnetic material such as ferrite is formed in a semicircular arc shape is disposed further outside the excitation coil 41, and the core 42 is fixed to a support member 43 and is located at a position close to the excitation coil 41. It is supported. In this embodiment, the relative magnetic permeability of the core 42 is 2500.

  A high-frequency AC current of 10 kHz to 1 MHz, preferably a high-frequency AC current of 20 kHz to 800 kHz is supplied to the excitation coil 41 from a drive power supply (not shown), whereby an alternating magnetic field is generated around the excitation coil 41.

  The alternating magnetic field acts on the heat generating layer such as the heating roller 39 in a portion where the heating roller 39 and the fixing belt 5 are in circumferential contact and in the vicinity thereof, and inside these, the change in the magnetic field due to the alternating magnetic field is prevented. Eddy current flows in the direction.

  Joule heat is generated by the eddy current and electric resistance of the heating roller 39 and the like, whereby the heating roller 39 and the like generate heat by electromagnetic induction.

  For example, a temperature sensor 45 composed of a thermistor or the like contacts the inner surface of the fixing belt 5 near the entrance side of the nip portion 22 and detects the temperature of the inner surface of the fixing belt 5.

(Embodiment 1)
The method for manufacturing the fixing belt according to the first embodiment of the present invention includes:
A step of applying a release layer containing a fluororesin to the molding surface of the mold,
Baking the applied release layer,
A step of applying an elastic layer on the side opposite to the molding surface as viewed from the release layer,
Baking the applied elastic layer;
A step of applying a support layer containing a heat-resistant synthetic resin on the side opposite to the molding surface as viewed from the elastic layer,
Baking the applied support layer,
Removing unevenness of the baked support layer;
Releasing the release layer, the elastic layer, and the support layer from the molding surface.

  FIG. 3 is a flowchart showing each step in the first embodiment of the present invention, and FIGS. 4A to 4F are cross-sectional views showing a process of forming each of the layers. Here, as in FIG. 10, the molding surface 1 a is illustrated as a plane in FIG. 4, but this is for the purpose of making the illustrated result easy to understand, and the molding surface 1 a in the present embodiment is actually It is a cylindrical surface.

  Next, each layer constituting the fixing belt 5 will be described. First, the release layer 2 will be described. The fluororesin used for the release layer 2 is a group consisting of an ethylene tetrafluoride polymer (PTFE), an ethylene tetrafluoride-perfluoroalkoxyethylene copolymer (PFA), and a fluoroethylene-propylene copolymer (PFEP). It is preferably at least one selected from

  The firing temperature of the release layer 2 is preferably from 330 to 430C. Within this temperature range, the film forming properties of the release layer 2 are good, and the release layer 2 does not deteriorate. The thickness of the release layer 2 after firing is preferably 5 to 50 μm. Within this thickness range, the wear resistance of the release layer 2 is good, and the release layer 2 is not broken while maintaining a high surface hardness. In particular, the range of 15 to 25 μm is more preferable.

  Fixing belts using these fluororesins as the release layer 2 are excellent in terms of fixing properties, surface hardness, surface release properties, surface roughness, durability, and film thickness freedom. It has excellent properties, release properties and durability of the release layer 2.

  In addition, a conductive material, a wear-resistant material, and a good heat conductive material can be added as a filler to the fluororesin as needed.

  Next, the elastic layer 3 will be described. The elastic layer 3 is preferably made of a silicone rubber having a JIS hardness of A1 to A80 degrees. Within this JIS hardness range, it is possible to prevent a decrease in the strength of the elastic layer 3 and a failure in adhesion while preventing a failure in fixability. Specific examples of the silicone rubber include one-component, two-component, three-component or more silicone rubber, RTV-type or HTV-type silicone rubber, condensation-type or addition-type silicone rubber.

  The firing temperature of the elastic layer 3 is preferably 150 to 300 ° C. Within this temperature range, deterioration and hardening of the elastic layer 3 do not occur while preventing volatile components remaining in the elastic layer 3 and insufficient strength. Further, the thickness of the elastic layer 3 after firing is preferably 30 to 1000 μm. Within this thickness range, the heat insulating property can be suppressed to a low level while maintaining the elastic effect of the elastic layer 3, and the energy saving effect can be exhibited. In particular, 150 to 300 μm is more preferable.

  Next, the support layer 4 will be described. The support layer 4 is preferably made of a heat-resistant synthetic resin. The heat-resistant synthetic resin is preferably polyimide (PI) or polyamideimide (PAI).

  Further, the firing temperature of the support layer 4 is preferably 150 to 300 ° C. In this temperature range, the strength of the support layer 4 does not decrease and the elastic layer 3 does not deteriorate. The thickness of the support layer 4 after firing is preferably 50 to 200 μm. Within this thickness range, the strength and wear durability of the support layer 4 are maintained, the flexibility is not reduced, and the heat insulating property can be suppressed to a low level. As will be described later, since the support layer 4 is polished to remove surface irregularities, an extra amount (for example, about 5 to 20 μm) of the amount of shaving accompanying this polishing is secured.

  Next, a method of manufacturing the fixing belt according to the first embodiment will be described. First, prior to the description of each process using FIGS. 3 and 4, application, drying and baking of each layer will be described with reference to FIG. 5, and then polishing of the support layer will be described with reference to FIG.

  FIG. 5 is a schematic perspective view of a fixing belt manufacturing apparatus according to one embodiment of the present invention.

  As shown in FIG. 5, this manufacturing apparatus has a coating stage on the front side and a heater stage on the back side. Then, the molding die 1 is driven by rotating means (not shown) to move the coating stage and the heater stage along the moving path 50 in the direction of the arrow N3 while rotating in the direction of the arrow R1.

  An applicator 52 having a spray for applying a resin or the like constituting each layer to the molding surface 1a of the mold 1 vertically downward is provided on the application stage. The applicator 52 is driven by moving means (not shown) to reciprocate in the direction of the arrow N4 to apply the resin evenly to the molding surface 1a.

  Further, the heater stage is provided with a heater 51, and by setting heating conditions (time, temperature, etc.) by the heater 51 according to a predetermined profile, each layer applied to the outermost periphery of the molding surface 1a is removed. , Dried or fired.

  FIG. 6 is a schematic perspective view of a polishing apparatus according to one embodiment of the present invention. As shown in FIG. 6, in this polishing apparatus, similarly to FIG. 5, the molding die 1 is supported in a rotating state in the direction of arrow R1.

  Also, the first roller 53, the second roller 54, and the third roller 54, whose axial directions are parallel to the central axis of the rotation, are arranged in a V-shape in a longitudinal sectional view, and the first roller 53, the second roller 54 Then, the band-shaped file 56 is adjusted in the order of the third roller 54. The file 56 may be about # 400, and at least the surface facing the molding surface 1a is a friction surface.

  Then, the second roller 54 is brought into contact with the support layer 4 located at the outermost periphery of the molding surface 1a as shown by an arrow N4. Further, while rotating the molding die 1 in the direction of the arrow R1, the support layer 4 on the molding surface 1a and the portion of the file 56 that orbits the second roller 54 are relatively moved in the axial direction of the molding die 1. Thereby, the outer peripheral portion of the support layer 4 is polished. According to the study of the present inventors, the unevenness of the support layer 4 is about 5 to 8 μm at the maximum, and the removal amount of the support layer 4 of about 10 μm is enough to remove the unevenness. .

  The above numerical values are merely examples, and the present invention is not limited to these numerical values.

  In order to refresh the friction surface of the file 56, the band-shaped file 56 may be fed by a predetermined amount in the direction of the arrow N5.

  Next, based on the above description, each step of the method of manufacturing the fixing belt 5 according to the first embodiment will be described with reference to FIGS.

  First, in step 1 of FIG. 3, as shown in FIG. 4A, a mold 1 having a predetermined shape and having a molding surface 1a is prepared. In FIG. 4, the molding surface 1a is illustrated as a plane, but this is for the sake of clarity of the illustrated result, and the molding surface 1a of the present embodiment is actually a cylindrical surface that is convex downward. is there.

  Next, in Step 2 of FIG. 3, as shown in FIG. 4B, a release layer 2 containing a fluororesin is applied on the molding surface 1a. This application is performed on the application stage shown in FIG.

  Then, in step 3 of FIG. 3, the mold 1 is moved from the application stage to the heater stage, heated by the heater 51, and the applied release layer 2 is baked.

  Next, in Step 4 of FIG. 3, the mold 1 is returned from the heater stage to the application stage, and as shown in FIG. 4C, the outside of the mold release layer 2 (the molding surface as viewed from the mold release layer 2). 1a), the elastic layer 3 is applied.

  Then, in step 5 of FIG. 3, the mold 1 is moved from the application stage to the heater stage, heated by the heater 51, and the applied elastic layer 3 is baked.

  Further, in step 6 of FIG. 3, the mold 1 is returned from the heater stage to the coating stage, and as shown in FIG. 4D, the outside of the elastic layer 3 (the opposite of the molding surface 1a as viewed from the elastic layer 3). Side), a support layer 4 is applied.

  Then, in step 7 of FIG. 3, the mold 1 is moved from the application stage to the heater stage, heated by the heater 51, and the applied support layer 4 is baked.

  However, as described in the section of the background art, when the support layer 4 is applied, the thickness of the support layer 4 varies as shown in a thin portion 4a and a thick portion 4b shown in FIG. If the support layer 4 is baked in a state where there is variation, irregularities are formed on the fixing belt.

  Therefore, in step 8 of FIG. 3, as shown in FIG. 4F, the outermost periphery of the support layer 4 is polished by an appropriate amount by using the polishing apparatus of FIG. As a result, the irregularities are removed, and the fixing belt 5 has a smooth outer shape.

  Therefore, as shown in FIG. 7, in the nip portion, a recording medium (for example, recording paper or the like) 9 onto which the toner 8 has been transferred and the fixing belt 5 are sandwiched between the fixing roller 6 and the pressure roller 7. In this case, a uniform pressure acts on the recording medium 9 by the fixing belt 5 having excellent flatness, so that high recording quality can be maintained.

  Then, in step 9 in FIG. 3, the fixing belt 5 is released from the molding surface 1a, and the fixing belt 5 is turned upside down.

(Embodiment 2)
The method for manufacturing the fixing belt according to the second embodiment of the present invention includes:
A step of applying a release layer containing a fluororesin to the molding surface of the mold,
Baking the applied release layer,
A step of applying an elastic layer on the side opposite to the molding surface as viewed from the release layer,
Baking the applied elastic layer;
A step of applying a support layer containing a heat-resistant synthetic resin on the side opposite to the molding surface as viewed from the elastic layer,
Drying the applied support layer,
Removing unevenness of the dried support layer,
Firing the support layer;
A release layer, an elastic layer, and a support layer; and a step of releasing from the molding surface.

  Hereinafter, the present embodiment will be described focusing on differences from the first embodiment. Next, each step of the method for manufacturing the fixing belt 5 according to the second embodiment will be described with reference to FIGS.

  First, in step 11 of FIG. 8, as shown in FIG. 9A, a molding die 1 having a molding surface 1a having a predetermined shape is prepared.

  Next, in Step 12 of FIG. 8, as shown in FIG. 9B, a release layer 2 containing a fluororesin is applied on the molding surface 1a. This coating is performed on the coating stage shown in FIG.

  Then, in step 13 of FIG. 8, the mold 1 is moved from the application stage to the heater stage, heated by the heater 51, and the applied release layer 2 is baked.

  Next, in step 14 of FIG. 8, the mold 1 is returned from the heater stage to the coating stage, and as shown in FIG. 9C, the outside of the mold release layer 2 (the molding surface as viewed from the mold release layer 2). 1a), the elastic layer 3 is applied.

  Then, in step 15 of FIG. 8, the mold 1 is moved from the application stage to the heater stage, heated by the heater 51, and the applied elastic layer 3 is baked.

  Further, in step 16 of FIG. 8, the mold 1 is returned from the heater stage to the application stage, and as shown in FIG. 9D, the outside of the elastic layer 3 (the opposite of the molding surface 1a as viewed from the elastic layer 3). Side), a support layer 4 is applied.

  The above is the same as in the first embodiment. However, this embodiment is different in the subsequent steps.

  That is, in step 17 of FIG. 8, the mold 1 is moved from the application stage to the heater stage, heated by the heater 51, and the applied support layer 4 is dried. For this drying, the heating condition by the heater 51 may be, for example, 200 ° C. for 10 to 15 minutes.

  Next, in Step 18 of FIG. 8, as shown in FIG. 9 (f), the outermost periphery of the support layer 4 is polished by an appropriate amount by using the polishing apparatus of FIG. As a result, the irregularities are removed, and the fixing belt 5 has a smooth outer shape.

  Thereafter, in step 19 in FIG. 8, the mold 1 is moved from the application stage to the heater stage, heated by the heater 51, and the polished support layer 4 is fired.

  Then, in Step 20 of FIG. 8, the fixing belt 5 is released from the molding surface 1a, and the fixing belt 5 is turned upside down. Other points are the same as the first embodiment.

  In this embodiment, the unevenness of the dried support layer is removed. Therefore, the surface of the support layer opposite to the molding surface becomes flat, and the unevenness of the support layer is removed before the imidization of the support layer proceeds. Therefore, since the variation in the amount of shrinkage during firing is suppressed, the nonuniformity of the elastic deformation of the elastic layer is also suppressed, and the flatness of the fixing belt is further ensured.

(Embodiment 3)
In the first and second embodiments, the present invention is applied to the fixing belt. However, the present invention can be applied to a transfer belt as described below.

  Hereinafter, the image forming apparatus according to the third embodiment will be described with reference to FIGS. FIG. 10 is a sectional view of an image forming apparatus according to Embodiment 3 of the present invention.

  The image forming apparatus of FIG. 10 is based on a tandem system, as in FIG. However, the present invention is not limited to a tandem type image forming apparatus, and can be applied to various image forming apparatuses such as a black and white image forming apparatus and a frame sequential type image forming apparatus.

  Here, in the present embodiment, it is assumed that the recording medium corresponds to an A4 size recording medium (width: 197 mm), and an axis of about 210 to 230 mm (the longitudinal direction is a direction perpendicular to the plane of FIG. 10) is used unless otherwise specified. Shall be. In FIG. 10, the same components as those in FIG. 1 are denoted by the same reference numerals.

  In FIG. 10, the photosensitive drum 32 corresponds to a first image carrier. A roller having an arbitrary diameter can be selected as the photosensitive drum 32, the charging unit 33, and the developing roller. In the third embodiment, those having a diameter of 24 mm, 12 mm, and 20 mm are used, respectively.

  The photoconductor drum 32 is constituted by an organic photoconductor drum (OPC) in which a photosensitive layer of about 15 to 20 μm is provided on a 0.8 mm thick aluminum tube. The exposure unit 23 scans the surface of the photoconductor drum 32 with a laser beam to form a latent image. Although FIG. 10 illustrates the laser optical system, an LED array head or the like can also be used.

  The charging unit 33 contacts the photosensitive drum 32 at a pressure of about 500 to 1000 g (210 mm in the axial direction), and rotates in the same direction as the photosensitive drum 32. The charging unit 33 is formed by forming a conductive elastic layer around a metal shaft. When a voltage is applied from the metal shaft, the surface of the photosensitive drum 32 is charged to a desired potential.

In the present embodiment, the charging section 33 is formed by forming an elastic layer (resistance: 10 ⁶ Ω · cm, thickness: 3 mm) on a 6 mm metal shaft. The applied voltage may be DC, AC, or a combination of DC and AC. In this embodiment, the applied voltage is 1000 V DC, and the surface potential of the photosensitive drum 32 is about 500 V.

  As in FIG. 1, in order to form a color image, the photosensitive drum 32 corresponding to the yellow, magenta, cyan, and black toners, and the members arranged around the photosensitive drum 32 may be similar to each other. it can.

  Next, the transfer section will be described. In FIG. 10, the transfer belt 11 is a seamless endless type. Details of the method of manufacturing the transfer belt 11 will be described later. The transfer belt 11 is stretched around a driving roller 72 and a tension roller 13.

  The drive roller 72 rotates the transfer belt 11. The drive roller 12 may be a metal such as aluminum or iron, or a metal plated with nickel or the like, or urethane or silicone having a high friction coefficient on the surface in order to suppress slippage between the drive roller 12 and the transfer belt 11. Such as those provided with rubber.

  In the present embodiment, the outer diameter of the drive roller 12 is φ16 mm, which is approximately an integer of the interval (45 mm in the present embodiment) between the photosensitive drums 32 corresponding to each color (yellow, magenta, cyan, and black). Becomes 1.

  The tension roller 13 is urged by a spring or the like (not shown) to apply tension (for example, about 100 N) to the transfer belt 11. The tension roller 13 may be configured not to apply tension while the transfer belt 11 is not involved in image formation. In this embodiment, the tension roller 13 is electrically grounded.

  The first transfer roller 74 is arranged for each color (yellow, magenta, cyan, and black) so as to face the photosensitive drum 32 of each color via the transfer belt 11. In the present embodiment, the positional relationship between the photosensitive drum 32 and the first transfer roller 74 is determined such that the center of the photosensitive drum 32 and the center of the first transfer roller 74 match in the moving direction of the transfer belt 11. . However, the positional relationship is not limited to this. For example, the center of the first transfer roller 74 may be shifted from the positional relationship by several mm toward the downstream side of the movement of the transfer belt 11.

  In the present embodiment, the first transfer roller 74 of the present embodiment forms a sponge layer (thickness: 3 mm, made of foamed urethane rubber having a hardness of 25 degrees (Asker C)) on the surface of a metal shaft (diameter 6 mm). Be composed. A pressure of 300 g (210 mm in the axial direction) is applied to both ends of the first transfer roller 74 having an outer diameter of 12 mm toward the photosensitive drum 32. As a result, the first transfer roller 74 presses the photosensitive drum 32 via the transfer belt 11.

In this embodiment, when a voltage of 1000 V is applied, the resistance is 5 × 10 ³ Ω. Of course, the resistance value is not limited to this, and a resistance value of 1 × 10 ⁸ Ω or less can be used. When the center of the first transfer roller 74 is shifted to the downstream side of the movement of the transfer belt 11 with respect to the center of the photosensitive drum 32, the first transfer roller 74 is configured with only a metal shaft (no sponge layer). May be.

  Each first transfer roller 74 is connected to a first transfer power supply 75. In the present embodiment, the first transfer rollers 74 corresponding to the four colors are collectively connected to the first transfer power supply 75, but an individual power supply may be prepared for each color and connected. Alternatively, the first transfer power supply 75 and the first transfer roller 74 may be connected via an insertion resistor having a different resistance value for each color.

  In the present embodiment, the first transfer power supply 75 employs a constant voltage method in which the output voltage is constant. However, the present invention is not limited to this, and the first transfer power supply 75 keeps the output current constant. Or a mixed power supply (constant current-constant voltage) that performs some kind of feedback control.

  The second transfer roller 76 transfers the toner image (single color or plural colors) on the transfer belt 11 to a recording medium (second image carrier) 9. The second transfer roller 76 is connected to a second transfer power supply 77. As the second transfer power supply 77, a power supply similar to the first transfer power supply 75 can be used.

  Furthermore, the voltage / current applied to the second transfer roller 76 can be determined by detecting the current flowing through the tension roller 13 while the recording medium 9 does not pass.

  The same configuration as the first transfer roller 74 can be used for the second transfer roller 76. In this embodiment, a sponge layer (made of foamed sponge such as urethane, having a thickness of 5 mm and a hardness (Asker C) of 45 degrees) formed on a metal shaft (φ12 mm) and having an outer diameter of 22 mm is used. The hardness is not limited to this, and a hardness of 60 degrees or less on a JIS hardness A scale can be used.

In this embodiment, both ends of the transfer belt 11 are pressed with a force of 15 N on one side. Further, as the second transfer roller 76, a roller having a sponge layer formed thereon as described above or a roller having a coating layer provided on the surface may be used. The resistance is 5 × 10 ⁶ Ω when 1000 V is applied, but the resistance is not limited to this and can be used in the range of 1 × 10 ⁶ to 1 × 10 ⁸ Ω.

  The paper entry guide 81 is formed of a metal member, and guides the recording medium 9 between the second transfer roller 76 and the transfer belt 11, and is directly grounded or grounded via a resistance element. Is done.

  The timing roller 82 temporarily stops the recording medium 9 conveyed from a paper feed tray (not shown), and at a timing when the leading end of the image formed on the transfer belt 11 and the leading end of the recording medium 9 coincide with each other, The conveyance of the recording medium 9 is restarted. The timing roller 82 is directly grounded or grounded via a resistance element.

  The cleaning blade 79 corresponds to a cleaning unit, and removes toner remaining on the transfer belt 11. The cleaning auxiliary roller 80 corresponds to a supporting unit, and supports the leading edge of the cleaning blade 79 via the transfer belt 11.

As the cleaning blade 79, a single layer of rubber formed of a rubber material (such as urethane, which has a JIS hardness A of hardness of 50 to 90 degrees) or a plurality of layers of rubber having different hardness is attached. In the present embodiment, the cleaning blade 79 has a free end length of 8 mm and a thickness of 1.6 mm, and the cleaning blade 79 is disposed so as to have an angle of 10 ± 5 degrees with respect to the horizontal plane of the transfer belt 11. For the cleaning blade 79, the ratio of the free end length divided by the thickness is suitably from "4" to "6". Further, the Young's modulus of the cleaning blade 79 is suitably from 40 to 100 kgf / cm ² .

  In this embodiment, a φ10 metal shaft is used as the cleaning auxiliary roller 80. The pressing force of the cleaning blade 79 against the transfer belt 11 is 20 gf / cm, and the effective range of the pressing force is 10 to 30 gf / cm. The bite amount was 1 mm, but an appropriate range of the bite amount is 0.3 mm to 2.5 mm.

  The surface roughness of the support layer of the transfer belt 11 is suitably 10 to 20 μm as a 10-point average surface roughness. This roughness is desirably smaller than the surface roughness of the cleaning assisting roller 80, and is suitably about 5 to 15 μm.

  When the surface roughness is set as described above, the rigidity of the cleaning auxiliary roller 80 becomes larger than the rigidity of the transfer belt 11, and the transfer belt 11 follows the unevenness of the surface of the cleaning auxiliary roller 80. Wrinkles are not formed on the surface of the release layer, and the cleaning property is improved. In particular, the cleaning properties of the external additives added to the toner are improved, which is preferable.

  Conversely, if the surface roughness of the support layer of the transfer belt 11 is larger than the surface roughness of the cleaning auxiliary roller 80, the unevenness of the support layer of the transfer belt 11 is not absorbed, and wrinkles are formed on the surface of the release layer. And cleaning performance is reduced.

  In addition, by making the surface roughness of the first transfer roller 74 supporting the transfer belt 11 smaller than the surface roughness of the drive roller 12 and the tension roller 13, the transfer belt 11 , And the running of the transfer belt 11 is stabilized.

  Further, since the adhesion is enhanced, the toner and its additives can be prevented from entering the gap between the transfer belt 11 and these rollers 12, 13, and the running of the transfer belt 11 can be stabilized for a long period of time.

  In the case of this embodiment, since the support layer is manufactured from the release layer, the support layer is finished by polishing.

  According to the usual method, since it is manufactured from the support layer, in order to control the surface roughness, it is necessary to respond to the accuracy of the surface roughness of the mold, and maintenance such as measures against scratches is indispensable, It takes.

  On the other hand, as in the present embodiment, when the surface roughness is controlled by polishing the support layer in the final polishing step, such labor and cost are not required, and the production of the release layer or the elastic layer fails temporarily. Even in such a case, it is sufficient that the process does not proceed to the polishing process, which leads to an improvement in yield.

  Next, the operation of the image forming apparatus of FIG. 10 will be described.

  In the case of the tandem system, the image forming process is performed similarly for each color. Taking the case of yellow as an example, first, the surface of the photosensitive drum 32 is uniformly charged by the charging unit 33. Next, the exposure unit 23 scans the surface of the photosensitive drum 32 according to the image signal to form an electrostatic latent image. Next, the charged toner from the developing unit 34 is supplied to the photosensitive drum 32, and the electrostatic latent image is visualized to form a toner image.

  The first transfer power supply 75 applies a voltage (+400 to 1200 V) having a polarity (positive in the present embodiment) opposite to the charging polarity (minus in the present embodiment) of the toner by the first transfer roller 74 pressed from the back of the transfer belt 11. The toner image is transferred onto the transfer belt 11 by applying the voltage.

  In the tandem system, such an image is formed for each color, and toner images of each color are sequentially superimposed on the transfer belt 11. On the other hand, the timing roller 32 measures the timing of the conveyance of the recording medium 9 so that the front end of the recording medium 9 coincides with the front end of the toner image on the transfer belt 11, and when the timing is completed, the conveyance of the recording medium 9 is stopped. When started, the recording medium 9 comes into pressure contact with the transfer belt 11 via the rush guide 81.

  Thereby, the images superimposed on the transfer belt 11 are collectively transferred onto the recording medium 9. At this time, for the electrostatic transfer, a voltage (+1500 to 2000 V) having a polarity opposite to the charge polarity of the toner is applied to the second transfer roller 26 from the second transfer power supply 77.

  The cleaning blade 79 scrapes the toner remaining on the transfer belt 11 without being transferred to the recording medium 9, and the portion of the transfer belt 11 from which the toner has been scraped is used for the next image forming process.

  Next, a method for manufacturing a transfer belt according to the third embodiment of the present invention is basically the same as that described in detail in the first and second embodiments. Hereinafter, the manufacturing method of the present embodiment will be described including the characteristics required for the transfer belt.

First, the method of manufacturing the transfer belt according to the present embodiment includes:
A step of applying a release layer containing fluorine to the molding surface of the mold,
Baking the applied release layer,
A step of applying an elastic layer on the side opposite to the molding surface as viewed from the release layer,
Baking the applied elastic layer;
A step of applying a support layer containing a heat-resistant synthetic resin on the side opposite to the molding surface as viewed from the elastic layer,
Baking the applied support layer,
Removing unevenness of the baked support layer;
Releasing the release layer, the elastic layer, and the support layer from the molding surface.

  Next, each step of the manufacturing method will be described. In FIG. 11, the same components as those in FIG. 4 are denoted by the same reference numerals.

  First, each layer of the transfer belt 11 will be described with reference to FIG. The fluororesin used for the release layer 2 is a group consisting of ethylene tetrafluoride polymer (PTFE), ethylene tetrafluoride-perfluoroalkoxyethylene copolymer (PFA), and fluoroethylene-propylene copolymer (PFEP). Preferably, at least one selected from the group consisting of

  The firing temperature of the release layer 2 is preferably from 330 to 430C. Within this temperature range, the film forming property of the release layer 2 is good, and the release layer 2 does not deteriorate. Further, the thickness of the release layer 2 is preferably 5 to 50 μm. In this thickness range, the release durability of the release layer 2 is good, and the release layer 2 is not broken while maintaining a long release effect. In particular, the range of 10 to 20 μm is more preferable.

  A conductive agent, an anti-wear agent, and the like can be added to the release layer 2 as necessary. Examples of the conductive agent include carbon black, an ionic conductive agent, and a conductive resin. Specifically, titanium oxide, tin oxide, barium sulfate, aluminum oxide, strontium titanate, magnesium oxide, silicon oxide, silicon carbonate, silicon nitride, and the like can be used as the conductive inorganic fine particles. For example, it may be processed. The ionic conductive agent is, for example, an ammonium salt, an alkyl sulfonate, or a phosphate, and the conductive resin is, for example, polyvinyl aniline, polyvinyl pyrrole, or a quaternary ammonium salt.

Although not necessarily limited to these, it is preferable to use conductive inorganic fine particles from the viewpoint of controlling conductivity. The surface resistance of the transfer belt 11 of the present embodiment is 10 ⁹ to 10 ¹⁶ Ω / cm (using a Hiresta IP manufactured by Mitsubishi Yuka Co., HRS probe (inner ring φ 6 mm, outer ring 18 mm)). ) Is preferable, and 10 ¹¹ to 10 ¹² Ω / cm is more preferable.

  Next, the elastic layer 3 is preferably made of silicone rubber having a JIS hardness A of 1 to 80 degrees. When the hardness is within the range of JIS hardness A, it is possible to prevent a decrease in the strength of the elastic layer 3 and poor adhesion. The thickness is preferably from 30 to 1000 μm, and more preferably from 100 to 400 μm. Within this thickness range, when a toner image is transferred from the photosensitive drum 32 to the transfer belt 11, the occurrence of image defects such as so-called hollow images in which a part of a thin line or the like becomes defective in transfer is prevented. Can be suppressed.

  Here, if a long toner image is sparsely present in the sub-scanning direction, a phenomenon occurs in which the transfer belt 11 contacts only a portion where the toner image exists and does not contact other portions. When this phenomenon occurs, a blank image occurs. More specifically, it is considered that this phenomenon occurs because the pressure of the first transfer roller 74 is concentrated only on the portion of the transfer belt 11 where the toner image exists.

  Here, in the present embodiment, since the elastic layer 3 is formed on the transfer belt 11, the transfer belt 11 is flexibly deformed, and the pressure of the first transfer roller 74 is changed to a portion of the transfer belt 11 where no toner image exists. And the pressure concentration is suppressed. As a result, the occurrence of a hollow image can be suppressed. Further, in order to adjust the resistance, a conductive agent can be added to the elastic layer 3 as needed. The same conductive agent as that of the release layer 2 can be used as the conductive agent to be added.

  Next, the support layer 4 is preferably made of a heat-resistant synthetic resin. The heat-resistant synthetic resin is preferably polyimide (PI) or polyamideimide (PAI).

  The firing temperature of the support layer is preferably 150 to 300 ° C. In this temperature range, the strength of the support layer 4 does not decrease, and the elastic layer 3 does not deteriorate. The thickness of the support layer 4 after firing is preferably 50 to 200 μm. Within this thickness range, the flexibility of the support layer 4 does not decrease while maintaining the strength and wear durability.

  The transfer belt 11 is used by being wound around a plurality of shafts (a driving roller 12, a tension roller 13, and the like). Therefore, if the transfer belt 11 is left unused without being used for a long time, the transfer belt 11 is abnormally deformed, the contact between the shaft and the transfer belt 11 is reduced, slippage occurs, and misalignment occurs when colors are overlapped. Such as causing problems.

  However, if the thickness of the support layer 4 after firing is within the above range, such a problem does not occur. As will be described later, since the support layer 4 is polished after firing, it is necessary to add an extra amount (5 to 20 μm) of the polishing. Further, in order to adjust the resistance, a conductive agent can be added to the support layer 4 as needed. As the conductive agent to be added, the same material as the material described for the release layer 2 can be used.

It is preferable to configure the transfer belt 11 as described above and finally adjust the volume resistance of the entire transfer belt to 1 × 10 ⁶ Ω · cm to 1 × 10 ¹⁰ Ω · cm. Further, desirably, 1 × 10 ⁸ Ω · cm to 1 × 10 ⁹ Ω · cm (Hiresta IP, HRS probe manufactured by Mitsubishi Yuka Co., Ltd., inner diameter ring φ6 mm, outer diameter ring 18 mm), 250 V applied, 10 seconds after application ) Is valid.

  By keeping this volume resistance range, the transfer belt 11 can be used repeatedly, or the performance can be stabilized against environmental fluctuations. If the resistance exceeds the range, electric charges are accumulated inside by the voltage applied at the time of transfer, so that a predetermined voltage cannot be applied, and print quality deteriorates.

  On the other hand, when used in a range lower than this resistance range, the current applied in the primary transfer leaks from a plurality of shafts supporting the transfer belt 11 and cannot maintain an appropriate transfer voltage, resulting in poor transfer efficiency. It gets extremely worse.

  Next, a method of manufacturing the transfer belt according to the third embodiment will be described with reference to FIG. In the following steps, the manufacturing apparatus shown in FIG. 5 and the polishing apparatus shown in FIG. 6 used in the first embodiment can be used.

  First, as shown in FIG. 11A, a mold 1 having a molding surface 1a having a predetermined shape is prepared. In FIG. 11, the molding surface 1a is shown as a plane, but this is for the sake of easy understanding of the illustrated result, and the molding surface 1a of the present embodiment is actually a downwardly convex cylindrical shape.

  Next, as shown in FIG. 11B, a release layer 2 containing a fluororesin is applied on the molding surface 1a by, for example, a spray arranged vertically downward.

  Next, the mold 1 is heated and fired. At the time of firing, not only is the temperature maintained uniquely at a desired temperature for a predetermined time, but the temperature raising time may be performed according to a profile set in advance by a program.

  Next, as shown in FIG. 11C, the elastic layer 3 is applied to the outside of the release layer 2.

  Next, the mold 1 is heated again, and the elastic layer 3 is fired at a desired method and at a desired temperature.

  Next, as shown in FIG. 11D, a support layer 4 is applied on the elastic layer 3, and the applied support layer 4 is heated and fired.

  However, when the support layer 4 is applied, as shown in FIG. 11D, a thin portion and a thick portion are often formed, and if it is as it is, the transfer belt 11 will have irregularities after firing.

  Therefore, in order to make the state shown in FIG. 11E, the surface of the support layer 4 is polished with a band-shaped file or the like by using the polishing apparatus shown in FIG. At the time of polishing, the center of the mold may be rotated about an axis, and a file may be pressed against the surface. In this case, the file is suitably about # 300 to # 1000, and the roughness of the file may be sequentially changed several times.

  In this embodiment, the surface roughness of the finally obtained support layer 4 is 10 to 20 μm in terms of 10-point average surface roughness. By doing so, the surface roughness of the transfer belt 11 can be made smaller than the surface roughness of the drive roller 12 and the surface roughness of the tension roller 13. As in Embodiment 1, etc., the polishing of the support layer 4 may be performed not after the support layer 4 is baked but after the support layer 4 is dried.

  Finally, the transfer belt 11 is released from the molding die 1 and the transfer belt 11 is turned upside down.

In this embodiment, the coefficient of linear thermal expansion of the release layer 2 is 10 × 10 ^{−5 to} 12 × 10 ⁻⁵ / ° C., and the coefficient of linear thermal expansion of the support layer 4 is about 5.4 × 10 ⁻⁵ / ° C. ° C.

  When the transfer belt 11 is heated to about 200 degrees with respect to the width of 200 mm and then cooled to room temperature, the release layer 2 contracts about 4 mm, and the support layer 4 contracts about 2 mm (about half of the release layer 2). In this way, if the difference in the coefficient of linear thermal expansion is provided, the difference in the inner diameter between the release layer 2 and the support layer 4 is absorbed, and when the transfer belt 11 is inverted, wrinkles are formed on the surface of the transfer belt 11. It can be prevented from occurring.

  The belt according to the present invention can be suitably used, for example, as a fixing belt or a transfer belt in an image forming apparatus such as a color laser printer.

Sectional view of an image forming apparatus according to an embodiment of the present invention. Sectional view of the fixing section Flow chart showing each step in Embodiment 1 of the present invention (A) Sectional view showing the process of forming each layer (b) Sectional view showing the process of forming each layer (c) Sectional view showing the process of forming each layer (d) Sectional view showing the process of forming each layer (e) ) Cross-sectional view showing the formation process of each layer. (F) Cross-sectional view showing the formation process of each layer. 1 is a schematic perspective view of a fixing belt manufacturing apparatus according to an embodiment of the present invention. Schematic perspective view of the polishing apparatus Enlarged sectional view of the nip Flow chart showing each step in Embodiment 2 of the present invention (A) Sectional view showing the process of forming each layer (b) Sectional view showing the process of forming each layer (c) Sectional view showing the process of forming each layer (d) Sectional view showing the process of forming each layer (e) Sectional view showing the process of forming each layer Sectional view of an image forming apparatus according to Embodiment 3 of the present invention. (A) Sectional view showing the process of forming each layer of the transfer belt (b) Sectional view showing the process of forming each layer of the transfer belt (c) Sectional view showing the process of forming each layer of the transfer belt (d) Transfer Sectional view showing the process of forming each layer of the belt (e) Sectional view showing the process of forming each layer of the transfer belt (A) Cross-sectional view showing a conventional process for forming each layer (b) Cross-sectional view showing a conventional process for forming each layer (c) Cross-sectional view showing a conventional process for forming each layer (d) Shows a conventional process for forming each layer Cross-sectional view (e) Cross-sectional view showing a conventional process of forming each layer Enlarged sectional view of conventional nip

Explanation of reference numerals

REFERENCE SIGNS LIST 1 Mold 1a Molding surface 2 Release layer 3 Elastic layer 4 Support layer 5 Fixing belt 6 Fixing roller 7 Pressure roller 9 Recording medium 11 Transfer belt 19 Fixing section 22 Nip section 39 Heating roller 44 Induction heating section 72 Drive roller 73 Follower Roller 79 Cleaning blade 80 Cleaning auxiliary roller

Claims (21)

A step of applying a release layer containing a fluororesin to the molding surface of the mold,
Baking the applied release layer,
A step of applying an elastic layer on the side opposite to the molding surface as viewed from the release layer,
Baking the applied elastic layer;
A step of applying a support layer containing a heat-resistant synthetic resin on the side opposite to the molding surface as viewed from the elastic layer,
Baking the applied support layer,
Removing the unevenness of the fired support layer;
A method of releasing the release layer, the elastic layer, and the support layer from the molding surface. A step of applying a release layer containing a fluororesin to the molding surface of the mold,
Baking the applied release layer,
A step of applying an elastic layer on the side opposite to the molding surface as viewed from the release layer,
Baking the applied elastic layer;
A step of applying a support layer containing a heat-resistant synthetic resin on the side opposite to the molding surface as viewed from the elastic layer,
Drying the applied support layer,
Removing the unevenness of the dried support layer,
Baking the support layer,
A method for manufacturing a belt for an image forming apparatus, comprising: a step of releasing the release layer, the elastic layer, and the support layer from the molding surface. The method for manufacturing a belt for an image forming apparatus according to claim 1, wherein the unevenness of the support layer is removed by polishing the support layer. The release layer, the elastic layer and the support layer, and simultaneously with or after releasing from the molding surface, the release layer, the elastic layer and the support layer are integrally turned over. The method for manufacturing a belt for an image forming apparatus according to claim 1, comprising a step. The fluororesin is selected from the group consisting of a tetrafluoroethylene polymer (PTFE), a tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA) and a fluoroethylene-propylene copolymer (PFEP). The method for producing a belt for an image forming apparatus according to claim 1, wherein at least one kind is selected. The method for producing a belt for an image forming apparatus according to claim 1, wherein the heat-resistant synthetic resin is selected from one or more of a group consisting of polyimide (PI) and polyamideimide (PAI). The image forming apparatus belt according to claim 1, wherein the image forming apparatus belt is at least one of a fixing belt and a transfer belt. A release layer containing a fluororesin, and located at the outermost layer,
Including a heat-resistant synthetic resin, and a support layer located at the innermost layer,
An elastic layer located between the release layer and the support layer,
The belt for an image forming apparatus, wherein the support layer is configured by removing irregularities from the baked support layer. A release layer containing a fluororesin, and located at the outermost layer,
Including a heat-resistant synthetic resin, and a support layer located at the innermost layer,
An elastic layer located between the release layer and the support layer,
The belt for an image forming apparatus, wherein the support layer is configured by removing irregularities from the dried support layer. The belt for an image forming apparatus according to claim 8, wherein the support layer has its irregularities removed by polishing. The fluororesin is selected from the group consisting of a tetrafluoroethylene polymer (PTFE), a tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA) and a fluoroethylene-propylene copolymer (PFEP). The belt for an image forming apparatus according to claim 8, wherein at least one kind is selected. The belt for an image forming apparatus according to claim 8, wherein the heat-resistant synthetic resin is selected from one or more of a group consisting of polyimide (PI) and polyamideimide (PAI). The image forming apparatus belt according to claim 8, wherein the image forming apparatus belt is at least one of a fixing belt and a transfer belt. An image forming unit that forms an image composed of toner,
A transfer roller for transferring the image formed by the image forming unit and formed of toner to a recording medium;
A fixing unit for fixing the toner transferred to the recording medium to the recording medium by melting and pressing,
The fixing unit,
A heating roller,
An induction heating unit that heats the heating roller by electromagnetic induction,
A fixing roller disposed apart from the heating roller,
A fixing belt that is wound around the heating roller and the fixing roller so as to be in contact with the fixing roller;
Facing the fixing roller, together with the fixing roller, forming a nip portion for nipping the recording medium to which the toner has been transferred, a pressure roller,
The image forming apparatus according to claim 8, wherein the fixing belt is the belt according to claim 8. A release layer containing a fluororesin, and located at the outermost layer,
Including a heat-resistant resin, and a support layer located at the innermost layer,
An elastic layer located between the release layer and the support layer,
A transfer belt wherein the linear thermal expansion coefficient of the release layer is larger than the linear thermal expansion coefficient of the support layer. A first image carrier holding an image composed of toner,
A transfer belt on which an image formed on the first image carrier is transferred,
The transfer belt contains a fluororesin, and a release layer located at the outermost layer, a heat-resistant resin, and a support layer located at the innermost layer, between the release layer and the support layer. An image forming apparatus, comprising: an elastic layer positioned on the support layer, wherein the support layer is formed by removing irregularities on at least one of the fired support layer and the dried support layer. Further comprising a plurality of rollers over which the transfer belt is stretched,
17. The image forming apparatus according to claim 16, wherein the surface roughness of the support layer from which the unevenness is removed is smaller than the surface roughness of the plurality of rollers. A first image carrier holding an image composed of toner,
A transfer belt on which an image formed on the first image carrier is transferred,
The transfer belt contains a fluororesin, and a release layer located at the outermost layer, a heat-resistant resin, and a support layer located at the innermost layer, between the release layer and the support layer. An image forming apparatus, comprising: an elastic layer located at a position closer to the support layer, wherein a linear thermal expansion coefficient of the release layer is larger than a linear thermal expansion coefficient of the support layer. 19. The image forming apparatus according to claim 18, wherein the support layer is configured by removing irregularities from at least one of the baked support layer and the dried support layer. Cleaning means for removing toner remaining on the transfer belt,
20. The image forming apparatus according to claim 19, wherein the cleaning unit includes an elastic blade unit. Further comprising a support means for supporting the cleaning means,
21. The image forming apparatus according to claim 20, wherein the transfer belt is sandwiched between the cleaning unit and the support unit.

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