JP2021196569A - Belt member, belt device, fixing device, and image forming apparatus - Google Patents

Abstract

To effectively reduce slide resistance when a belt member rotates.SOLUTION: An endless belt member 20 is used in an image forming apparatus. The belt member 20 has irregularities 30 on its inner peripheral surface 20a. The irregularities 30 have, in concave parts 42, small irregularities 31 having smaller surface roughness than that of the irregularities 30. The surface roughness Ra of the small irregularities 31 is 0.05 μm or more and 0.4 μm or less, and the surface roughness RSm of the small irregularities 31 is 5 μm or more and 20 μm or less.SELECTED DRAWING: Figure 4

Description

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

In an image forming apparatus such as a copying machine or a printer, an image forming apparatus using an endless belt member is known as a fixing apparatus for fixing a toner image on paper.

In this type of fixing device, when the belt member rotates, the belt member slides with respect to the nip forming member arranged inside the belt member, so that the sliding resistance generated between the belt member and the nip forming member (sliding resistance) ( Friction) causes problems such as an increase in rotational torque and accelerated wear of the belt member. Therefore, a lubricant such as grease or oil is generally applied to the inner peripheral surface of the belt member.

Further, as a measure for reducing the sliding resistance generated between the belt member and the nip forming member, Patent Document 1 (Japanese Patent Laid-Open No. 2010-139935) describes the belt member so that the lubricant can be stably held. A configuration has been proposed in which undulations having a pitch of 4 to 5 mm and a height of 3 to 5 μm and irregularities having a pitch of 0.1 mm and a height of 3 to 4 μm are formed on the inner peripheral surface of the above.

However, the frictional resistance generated between the belt member and the nip forming member tends to increase with time. Therefore, when the frictional resistance increases, there is a concern that the wear of the belt member is promoted. In particular, in a high-speed machine in which the rotation speed of the belt member is high, the load applied to the belt member is also large, so that the wear of the belt member becomes remarkable.

Further, the above-mentioned problems may occur not only in the belt member used in the fixing device but also in other belt members used in the image forming apparatus. Therefore, it is required to further reduce the sliding resistance of the belt member used in the image forming apparatus.

In order to solve the above problems, the present invention is an endless belt member used in an image forming apparatus, which has irregularities on the inner peripheral surface of the belt member, and has irregularities in the concave portions of the irregularities, rather than the irregularities. It is characterized by having small irregularities with a small surface roughness, the surface roughness Ra of the small irregularities being 0.05 μm or more and 0.4 μm or less, and the surface roughness RSm of the small irregularities being 5 μm or more and 20 μm or less. do.

According to the present invention, the sliding resistance when the belt member rotates can be effectively reduced.

It is a schematic block diagram of the image forming apparatus which concerns on one Embodiment of this invention. It is a schematic block diagram of the fixing device which concerns on this embodiment. It is a perspective view of the fixing device which concerns on this embodiment. It is an enlarged sectional view of the inner peripheral surface of the fixing belt which concerns on this embodiment.

Hereinafter, the present invention will be described with reference to the accompanying drawings. In each drawing for explaining the present invention, components such as members and components having the same function or shape are once described by giving the same reference numerals as much as possible, and then the description thereof will be described. Omit.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

The image forming apparatus 100 shown in FIG. 1 includes an image forming unit 200, a transfer unit 300, a fixing unit 400, a recording medium supply unit 500, and a recording medium discharging unit 600.

The image forming unit 200 is provided with four image forming units 1Y, 1M, 1C, 1Bk and an exposure apparatus 6. Each image forming unit 1Y, 1M, 1C, 1Bk is configured to be detachable from the image forming apparatus main body. Further, each image formation unit 1Y, 1M, 1C, 1Bk has basically the same configuration except that it contains developeres of different colors of yellow, magenta, cyan, and black corresponding to the color separation components of the color image. Is. Specifically, each image processing unit 1Y, 1M, 1C, 1Bk includes a photoconductor 2 which is an image carrier that carries an image on the surface, a charging roller 3 which is a charging means for charging the surface of the photoconductor 2. It includes a developing device 4 which is a developing means for forming a toner image on the photoconductor 2, and a cleaning device 5 which is a cleaning means for cleaning the surface of the photoconductor 2. The exposure apparatus 6 is a latent image forming means for forming an electrostatic latent image by exposing the charged surface of the photoconductor 2 based on the image information. In FIG. 1, only the photoconductor 2, the charging roller 3, the developing device 4, and the cleaning device 5 included in one image forming unit 1Bk are designated by reference numerals, and the other image forming units 1Y, 1M, and 1C have reference numerals. The code is omitted.

The transfer unit 300 is provided with a transfer device 8 that transfers an image onto paper, which is a recording medium. The recording medium on which the image is formed (transferred) may be a resin sheet such as an OHP sheet in addition to paper (including plain paper, thick paper, thin paper, coated paper, label paper, envelope, etc.). .. The transfer device 8 includes an intermediate transfer belt 11, four primary transfer rollers 12, and a secondary transfer roller 13. The intermediate transfer belt 11 is a transfer member that supports an image on the surface and transfers the image to paper, and is composed of an endless belt member. Each primary transfer roller 12 is in contact with another photoconductor 2 via the intermediate transfer belt 11. As a result, a primary transfer nip is formed between the intermediate transfer belt 11 and each photoconductor 2 so that the intermediate transfer belt 11 and each photoconductor 2 come into contact with each other. On the other hand, the secondary transfer roller 13 comes into contact with one of the plurality of rollers on which the intermediate transfer belt 11 is stretched via the intermediate transfer belt 11 to form a secondary transfer nip with the intermediate transfer belt 11. There is.

The fixing device 400 is provided with a heating device for heating the paper and a fixing device 9 for fixing the image on the paper by heat.

The recording medium supply unit 500 is provided with a paper feed cassette 14 for accommodating the paper P and a paper feed roller 15 for feeding the paper P from the paper feed cassette 14.

The recording medium ejection unit 600 is provided with a pair of paper ejection rollers 17 for ejecting paper to the outside of the image forming apparatus, and a paper ejection tray 18 on which the paper ejected by the paper ejection rollers 17 is placed.

Next, the printing operation of the image forming apparatus 100 according to the present embodiment will be described with reference to FIG.

When instructed to start the printing operation, the photoconductor 2 of each image forming unit 1Y, 1M, 1C, 1Bk, and the intermediate transfer belt 11 start rotating. Further, as the paper feed roller 15 rotates, the paper P is fed out from the paper feed cassette 14. The fed paper P comes into contact with the pair of timing rollers 16 and is temporarily stopped.

In each image forming unit 1Y, 1M, 1C, 1Bk, first, the surface of the photoconductor 2 is charged to a uniform high potential by the charging roller 3. Next, the exposure device 6 exposes the surface (charged surface) of each photoconductor 2 based on the image information of the document read by the document reader or the print image information instructed to print from the terminal. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image is formed on the surface of each photoconductor 2. Then, toner is supplied from the developing device 4 to the electrostatic latent image, and a toner image is formed on each photoconductor 2. When the toner image formed on each photoconductor 2 reaches the primary transfer nip (position of the primary transfer roller 12) with the rotation of each photoconductor 2, it is transferred so as to be sequentially overlapped on the rotating intermediate transfer belt 11. Will be done. Thus, a full-color toner image is formed on the intermediate transfer belt 11. Further, after the toner image is transferred from the photoconductor 2 to the intermediate transfer belt 11, the toner and other foreign substances remaining on each photoconductor 2 are removed by the cleaning device 5, and the photoconductor 2 has the next electrostatic latent image. Be prepared for the formation of.

The toner image transferred on the intermediate transfer belt 11 is conveyed to the secondary transfer nip (position of the secondary transfer roller 13) as the intermediate transfer belt 11 rotates, and is transferred on the paper P conveyed by the timing roller 16. Is transcribed into. Then, the paper P on which the toner image is transferred is conveyed to the fixing device 9, and the toner image is fixed on the paper P by the fixing device 9. After that, the paper P is ejected to the output tray 18 by the output roller 17, and a series of printing operations is completed.

The above description of the printing operation is about the operation when forming a full-color image, but one of the four image forming units can be used to form a monochromatic image, or two or three images can be formed. It is also possible to use the image unit to form a two-color or three-color image.

FIG. 2 is a schematic configuration diagram of the fixing device 9 according to the present embodiment, and FIG. 3 is a perspective view thereof. Hereinafter, the configuration of the fixing device 9 according to the present embodiment will be described with reference to FIGS. 2 and 3.

As shown in FIGS. 2 and 3, the fixing device 9 according to the present embodiment includes a fixing belt 20, a pressure roller 21, a halogen heater 22, end heaters 27A and 27B, and a nip forming member 23. It includes a reflective member 24, a stay 25, a heat transfer assisting member 26, and a belt holding member 28.

The fixing belt 20 is a fixing member that is arranged on the side of the paper P on which the unfixed image is supported and fixes the unfixed image on the paper P. The fixing belt 20 is composed of an endless belt member. Further, the fixing belt 20 is rotatably held by a pair of belt holding members 28 (see FIG. 3) inserted at both ends in the longitudinal direction Z thereof. Each belt holding member 28 is formed in a flange shape, for example, and is inserted inside the fixing belt 20 with a margin. Therefore, the fixing belt 20 is rotatably held by a pair of belt holding members 28 in a non-tensioned state (so-called free belt method in which tension is not applied to the belt).

The pressure roller 21 is a rotating body that comes into contact with the outer peripheral surface of the fixing belt 20. Specifically, the pressure roller 21 includes a core metal, an elastic layer made of foamable silicone rubber, silicone rubber, fluororubber, etc. provided on the surface of the core metal, and PFA or PFA provided on the surface of the elastic layer. It is composed of a release layer made of PTFE or the like. The pressure roller 21 is pressurized (pressure-welded) to the fixing belt 20 by an urging member such as a spring, and a nip portion N is formed between the fixing belt 20 and the pressure roller 21. Further, the pressure roller 21 is configured to be rotationally driven by a drive source provided in the image forming apparatus main body. When the pressure roller 21 is rotationally driven, the driving force is transmitted to the fixing belt 20 at the nip portion N, so that the fixing belt 20 is driven to rotate. As shown in FIG. 2, when the paper P carrying the unfixed image enters between the fixing belt 20 and the pressure roller 21 (nip portion N), the rotating fixing belt 20 and the pressure roller 21 cause the paper. While the P is being conveyed, it is heated and pressurized, and the unfixed image is fixed on the paper P.

In the present embodiment, the pressure roller 21 is a solid roller, but a hollow roller may be used. In that case, the heater may be arranged inside the pressure roller 21. Further, when the pressure roller 21 does not have an elastic layer, the heat capacity becomes small, so that the fixing property is improved. However, on the other hand, when the unfixed toner is fixed, minute irregularities on the belt surface may be transferred to the image, resulting in uneven gloss on the solid portion of the image. In order to prevent this, it is desirable that the pressure roller 21 has an elastic layer having a thickness of 100 μm or more. By having an elastic layer having a thickness of 100 μm or more, it is possible to absorb minute irregularities due to elastic deformation of the elastic layer, and it is possible to avoid the occurrence of uneven gloss. The elastic layer of the pressure roller 21 may be solid rubber, but if there is no heater inside the pressure roller 21, sponge rubber can also be used. The sponge rubber is preferable to the solid rubber in that the heat insulating property is improved and the heat of the fixing belt 20 is less likely to be taken away.

The halogen heater 22 is a heating source that is arranged inside the fixing belt 20 and heats the inner peripheral surface of the fixing belt 20 by directly irradiating it with light (for example, infrared light). As such a heating source, other radiant heat type heaters such as carbon heaters and ceramic heaters can be used in addition to the halogen heaters. It is also possible to use an electromagnetic induction heating type heating source. In the present embodiment, the two heaters 22 are arranged in the fixing belt 20, but the number of heaters 22 may be one or three or more.

The end heaters 27A and 27B are a pair of end heat sources that heat both ends of the fixing belt 20 in the longitudinal direction with the nip portion N. The end heaters 27A and 27B are independently arranged at positions separated from each other in the longitudinal direction of the fixing belt 20, and are integrally provided on the nip forming member 23.

The nip forming member 23 is a member that is arranged inside the fixing belt 20 and receives a pressure from the pressure roller 21 to form a nip portion N between the fixing belt 20 and the pressure roller 21. In the present embodiment, the nip forming member 23 is in contact with the inner peripheral surface of the fixing belt 20 via the heat transfer assisting member 26, but the heat transfer assisting member 26 is omitted and the nip forming member 23 is the fixing belt 20. May be in direct contact with the inner peripheral surface of the. As the material of the nip forming member 23, it is desirable to use a heat-resistant member having a heat-resistant temperature of 200 ° C. or higher. Specifically, as the material of the nip forming member 23, a polyether sulfone (PES), a polyphenylene sulfide (PPS), a liquid crystal polymer (LCP), a polyether nitrile (PEN), a polyamide-imide (PAI), and a polyether ether ketone Examples thereof include general heat-resistant resins such as (PEEK). By forming the nip forming member 23 with such a heat-resistant member, it is possible to prevent the nip forming member 23 from being deformed by heat in the fixing temperature range, so that a stable state of the nip portion N can be ensured and the output can be obtained. The image quality can be stabilized.

The stay 25 is a support member that supports the nip forming member 23 by coming into contact with the side of the nip forming member 23 opposite to the pressure roller 21 side. By supporting the nip forming member 23 by the stay 25, the bending of the nip forming member 23 due to the pressure of the pressure roller 21, particularly the bending of the nip forming member 23 in the longitudinal direction of the fixing belt 20 is suppressed, and the width is uniform. Nip portion N is formed. As the material of the stay 25, an iron-based metal material such as SUS or SECC is preferable in order to secure rigidity.

The reflective member 24 is a member that reflects heat and light (for example, infrared light) radiated from the heater 22. The heat and light of the heater 22 are reflected toward the fixing belt 20 by the reflecting member 24, so that the fixing belt is efficiently heated. Further, the reflective member 24 is arranged between the stay 25 and the heater 22, and the heating of the stay 25 by the heater 22 can be suppressed. Therefore, wasteful consumption of heat energy can be reduced, and energy saving can be achieved.

Further, the stay 25 may have the function of the reflective member 24. For example, by mirror-treating the facing surface of the stay 25 facing the heater 22, the stay 25 can be configured to also function as the reflecting member 24. In this case, since it is not necessary to separately provide the reflective member 24, it is advantageous for miniaturization and cost reduction.

The heat transfer assisting member 26 is a member that is interposed between the nip forming member 23 and the fixing belt 20 to transfer the amount of heat of the fixing belt 20 in the longitudinal direction thereof and suppress the variation in the surface temperature of the fixing belt 20. The heat transfer assist member 26 is made of a high thermal conductivity material having a higher thermal conductivity than the nip forming member 23. As the material of the heat transfer assist member 26, for example, copper, aluminum, silver, or the like can be used. In the present embodiment, the facing surface of the heat transfer assisting member 26 facing the inner peripheral surface of the fixing belt 20 is formed in a planar shape, but may have a concave shape or another shape. When the facing surface of the heat transfer assist member 26 has a concave shape, the nip portion N also has a concave shape following this, and the separability of the paper P with respect to the fixing belt 20 is improved.

By the way, in the fixing device 9 provided with the fixing belt 20 as described above, when the fixing belt 20 rotates, the fixing belt 20 slides with respect to the heat transfer assist member 26. At this time, if the sliding resistance generated between the fixing belt 20 and the heat transfer assisting member 26 increases with time, there is a concern that the fixing belt 20 may be worn or the rotational torque may increase. In particular, in the case of a high-speed machine, the load on the fixing belt due to the sliding resistance becomes large, so that the fixing belt may be significantly worn. Further, such a problem is not limited to the case where the member in contact with the inner peripheral surface of the fixing belt 20 is the heat transfer assisting member 26, and the nip forming member 23 and other members are placed on the inner peripheral surface of the fixing belt 20 ( The same can occur in the case of direct) contact. That is, in a configuration in which a sliding contact member that is in sliding contact with the inner peripheral surface of the rotating fixing belt 20 is provided, sliding resistance is generated between the sliding contact member and the fixing belt 20. There is a risk of wear of the fixing belt 20. Therefore, in the fixing device 9 in the present embodiment, the fixing belt 20 is configured as follows in order to suppress the wear of the fixing belt 20.

FIG. 4 is an enlarged cross-sectional view of the inner peripheral surface of the fixing belt according to the present embodiment. In FIG. 4, the upper side is the inside of the fixing belt (inner diameter side), and the lower side is the outside of the fixing belt (outer diameter side).

As shown in FIG. 4, in the fixing belt 20 according to the present embodiment, the inner peripheral surface 20a has a unevenness 30 having a relatively large surface roughness (difference in unevenness) and a surface roughness (more than the unevenness 30). Small unevenness 31 with a small unevenness difference) is provided. The unevenness 30 has a large number of convex portions 41 and a large number of concave portions 42 alternately provided over the entire circumferential direction (rotational direction) of the fixing belt 20. Here, assuming that the intermediate position of the heights from the top to the lowest of the convex portions 41 and the concave portions 42 adjacent to each other is the intermediate point m, the convex portions 41 and the concave portions 42 in the present invention are classified with the intermediate point m as a boundary. It means the convex and concave parts that have been made. That is, the portion protruding in the inner diameter direction (upper in FIG. 4) between the intermediate points m adjacent to each other is the convex portion 41, and is recessed in the outer diameter direction (lower in FIG. 4) between the intermediate points m adjacent to each other. The portion is a recess 42.

The small unevenness 31 is mainly provided in the concave portion 42 of the unevenness 30 configured as described above. Further, the small unevenness 31 is configured so that the surface roughness Ra is 0.05 μm or more and 0.4 μm or less, and the surface roughness RSm is 5 μm or more and 20 μm or less. Each surface roughness Ra, RSm is an arithmetic mean roughness and an average length of curved elements measured by a method according to JIS B 0601.

<Measurement method of surface roughness Ra and RSm of small unevenness>
In this embodiment, the surface roughness Ra and RSm of each of the small irregularities 31 were measured using a laser microscope "VK-X250" manufactured by KEYENCE CORPORATION. The measurement conditions at that time are as follows.
(1) Measurement length: Length of each recess 42 (2) Cutoff frequency: 0.025 mm
(3) Measurement points: 10 points (average value)

As described above, in the fixing belt 20 according to the present embodiment, the fine unevenness 31 is formed in the concave portion 42 provided on the inner peripheral surface 20a, and the surface roughness Ra of the small unevenness 31 is 0. By being configured so that the surface roughness RSm is 5 μm or more and 20 μm or less at 05 μm or more and 0.4 μm or less, the contact angle between the surface of the small unevenness 31 and the lubricant becomes large, and the small unevenness 31 Oil repellency (liquid repellency), so-called lotus effect, can be obtained. Due to this Lotus effect, the lubricant in the concave portion 42 is easily supplied to the convex portion 41. That is, in order to improve the lubricant supply performance to the convex portion 41, which is harder to hold the lubricant than the concave portion 42, the lubricant is uniformly or nearly uniformly dispersed on the inner peripheral surface 20a of the fixing belt 20, and is localized. It becomes possible to suppress the occurrence of lubricant shortage over time. As a result, the frictional resistance generated between the fixing belt 20 and the heat transfer assisting member 26 can be effectively reduced, and the wear of the fixing belt 20 and the increase in the rotational torque can be suppressed for a long period of time. ..

As described above, according to the fixing belt 20 according to the present embodiment, the durability of the fixing belt 20 can be improved, so that the fixing belt 20 is less likely to be worn or damaged, and the reliability is improved. In particular, in a high-speed machine in which a load is likely to be applied to the fixing belt, a large effect (belt wear suppressing effect) can be obtained by applying the fixing belt according to the present embodiment.

Further, in order to enable the lubricant to be more effectively dispersed and held on the inner peripheral surface 20a of the fixing belt 20, the surface roughness Ra of the unevenness 30 is 0.7 μm or more and 3.0 μm or less, and the surface roughness Ra is 0.7 μm or more and 3.0 μm or less. It is preferable that the surface roughness RSm of the unevenness 30 is 150 μm or more and 400 μm or less. By setting the surface roughness Ra and RSm of the unevenness 30 within such a range, it becomes easy to disperse and hold the lubricant, and local wear can be suppressed more effectively. In addition, since the contact area between the fixing belt 20 and the heat transfer assisting member 26 can be reduced, the frictional resistance can be further reduced.

Here, the surface roughness Ra and RSm of the unevenness 30 can be measured by a measuring method based on JIS B 0601, similarly to the surface roughness Ra and RSm of the small unevenness 31 described above. The specific measurement method (measurement conditions) is as follows.

<Measurement method of surface roughness Ra and RSm of unevenness>
In this embodiment, the surface roughness Ra and RSm of the unevenness 30 were measured by using a laser microscope "VK-X250" manufactured by KEYENCE CORPORATION under the following measurement conditions.
(1) Measurement length: 3 mm
(2) Cutoff frequency: 0.8 mm
(3) Measurement points: 10 points (average value)

Hereinafter, the components and the manufacturing method of the fixing belt according to the present embodiment will be described.

<Components of fixing belt>
The fixing belt has an endless (cylindrical) base material made of at least polyimide or the like. The fixing belt is not limited to a single-layer structure having only a base material, and may be a belt member composed of a plurality of layers. When the fixing belt is composed of a plurality of layers, a plurality of polyimide layers may be used, or a layer containing a material other than polyimide may be used with the polyimide layer as a base material. For example, the fixing belt has a base material made of a polyimide layer, an elastic layer such as silicone rubber provided on the outer peripheral surface of the base material, and a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer provided on the outer peripheral surface of the elastic layer. It may have a three-layer structure having a release layer made of coalesced (PFA), polytetrafluoroethylene (PTFE), or the like. Further, the fixing belt may have a two-layer structure composed of a base material and an elastic layer.

Further, the fixing belt may contain conductive particles. The conductive particles are not particularly limited, and for example, metal oxides, carbon black, ionic conductive agents, conductive polymer materials, and the like can be used. Since the fixing belt contains conductive particles, the fixing belt is charged, the charging of the fixing belt is suppressed, and the recording medium (paper) and the fixing belt are suppressed from being electrostatically adsorbed to be stable. The recording medium can be ejected.

Examples of the metal oxide include zinc oxide, tin oxide, titanium oxide, zirconium oxide, aluminum oxide, silicon oxide and the like. In addition, examples of the metal oxide include those obtained by subjecting the above metal oxide to a surface treatment in advance in order to improve dispersibility. Examples of carbon black include Ketjen black, furnace black, acetylene black, thermal black, and gas black. Examples of the ionic conductive agent include tetraalkylammonium salt, trialkylbenzylammonium salt, alkylsulfonate, alkylbenzenesulfonate, alkylsulfate, gluserine fatty acid ester, sorbitan fatty acid ester, polyoxyethylenealkylamine, and polyoxy. Examples thereof include ethylene fatty alcohol ester, alkyl betaine, lithium perchlorate and the like. Moreover, polyaniline and the like can be mentioned as a conductive polymer material. Further, only one kind of conductive particles may be used, or a plurality of kinds of conductive particles may be used in combination as needed.

Further, the fixing belt may contain other additives such as a dispersion aid, a reinforcing material, a lubricating material, a heat conductive material, and an antioxidant, depending on desired properties.

Further, the average thickness of the polyimide layer of the fixing belt is preferably 60 μm or more and 140 μm or less. When the average thickness of the polyimide layer of the fixing belt is 60 μm or more and 140 μm or less, the strength of the fixing belt can be ensured and sufficient heat transferability can be provided. When the fixing belt has a three-layer structure including a polyimide layer, an elastic layer, and a release layer, the thickness of the entire fixing belt can be about 400 μm to 500 μm. The average thickness of the polyimide layer of the fixing belt is an average value of values measured at any 10 points in the fixing belt. For the thickness measurement, a general-purpose product such as a pointer type film thickness meter or an eddy current type film thickness meter can be used, and for example, an electric micrometer manufactured by Anritsu Co., Ltd. can be used.

The polyimide constituting the polyimide layer of the fixing belt is not particularly limited, and an aromatic polyimide can be preferably used. The aromatic polyimide is obtained, for example, by reacting an aromatic polyvalent carboxylic acid anhydride or a derivative thereof with an aromatic diamine via a polyamic acid (polyimide precursor). Aromatic polyimide is insoluble in a solvent or the like due to its rigid main chain structure, and has an insoluble property. Therefore, first, a polyimide precursor (polyamic acid) soluble in an organic solvent is synthesized by a reaction between an aromatic polyvalent carboxylic acid anhydride and an aromatic diamine. At the stage of this polyamic acid, molding is performed by various methods, and the molded polyamic acid is dehydrated by heating or a chemical method to be cyclized (imidized) to obtain polyimide. Imidization by heating is a method of converting a polyamic acid into a polyimide by heat-treating it to, for example, 200 ° C. to 350 ° C., and is a simple and practical method for obtaining a polyimide (polyimide resin). The polyamic acid which is a precursor of the polyimide constituting the fixing belt according to the present embodiment can be produced by a known method by using the above-mentioned solvent contained in the polyimide layer of the fixing belt as a solvent in the polymerization reaction.

<Manufacturing method of fixing belt>
The outline of the manufacturing method of the fixing belt is as follows. First, a coating solution containing a polyimide precursor is applied to the outer surface of a mold (support) of a cylindrical fixing belt, and then a coating containing the polyimide precursor is applied. Form a membrane. Next, the formed coating film is converted into a polyimide resin by heating a cylindrical mold, and the solvent is further evaporated. Finally, the polyimide resin is removed from the cylindrical mold. As a result, a fixing belt is obtained.

Next, a detailed manufacturing method of the fixing belt will be described with an example.

As the cylindrical mold for molding the fixing belt, a metal mold can be used. While slowly rotating the mold, the coating liquid containing the polyimide precursor is uniformly applied to the entire outer surface of the cylindrical metal mold using a liquid supply device such as a nozzle or a dispenser. And cast (form a coating film). After that, the rotation speed is increased to a predetermined speed, and when the predetermined speed is reached, the rotation speed is maintained at a constant speed, and the rotation is continued for a desired time. Then, the temperature is gradually raised while rotating the mold to evaporate the solvent in the coating film at a temperature of 80 ° C. to 150 ° C. In this process, it is preferable to efficiently circulate and remove atmospheric vapor (volatile solvent, etc.).

Then, when a self-supporting film is formed, the temperature is further raised stepwise, and finally, high-temperature heat treatment (calcination) is performed at about 200 ° C. to 350 ° C. As a result, the polyimide precursor is imidized (converted). At this time, it is more desirable to heat from the inside of the metal mold. Any heater may be used as long as such a heating means can be applied. Specifically, examples of the heater include a halogen heater, an IH heater, and the like.

The method of heating the mold is roughly classified into a method of heating from the outer surface of the cylindrical mold and a method of heating from the inside, and can be appropriately selected depending on the purpose. In order to obtain the fixing belt according to the present embodiment, it is effective to apply a coating liquid containing a polyimide precursor to the outer surface of a cylindrical mold and heat it from the inside of the mold.

The method for manufacturing the fixing belt is not limited to the above-mentioned method, and other methods can be appropriately selected depending on the intended purpose. As described above, other additives such as conductive particles, dispersion aids, reinforcing materials, lubricants, heat conductive materials, and antioxidants are dispersed in the polyimide precursor solution (polyamic acid solution) as needed. You may use the coated liquid.

The support is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a cylindrical metal mold or the like is mentioned, and a polyimide precursor solution is applied to the outer surface of the mold. The type of metal used for the mold is preferably stainless steel or aluminum from the viewpoint of durability and workability, but is not limited to this. Concavities and convexities are formed on the surface of the mold, and examples of the method for forming the irregularities include, but are not limited to, blasting. As blasting, first blasting (primary blasting) with particles with a large count (small particle size) and then blasting (secondary blasting) with particles with a small count (large particle size). The inner surface shape of the belt of the present invention can be easily obtained. At this time, the one with a large count is preferably around # 1000 to 4000, and the one with a small count is preferably around # 150 to # 30. As the material of the blast particles, metal oxides such as silica, alumina, glass and zirconia are preferable in terms of processability, but the blast particles are not limited to this.

<Lubricant>
As the lubricant applied to the inner peripheral surface of the fixing belt, it is preferable to use a lubricant having high heat resistance (for example, having heat resistance of 200 ° C. or higher). By using a lubricant having high heat resistance, the frictional resistance generated between the fixing belt and the sliding contact member can be reduced for a long period of time, and the durability of the fixing belt can be improved. Specifically, as the lubricant, a lubricant containing at least one of silicone oil, fluorosilicone oil, fluorine oil, and grease based on them can be applied.

Subsequently, the effect confirmation test of the present invention will be described.

<Effect confirmation test>
In this test, the fixing belts according to Examples 1 to 9 of the present invention and Comparative Examples 1 to 4 different from the present invention shown in Table 1 below are used as an electrophotographic image forming apparatus (imagioColor 5100 manufactured by Ricoh Co., Ltd.). ), And whether there is an abnormality in the initial rotation torque generated in the fixing device at the start of driving and the post-passing rotation torque generated in the fixing device when 3 million sheets of paper are fixed. I confirmed that. In Table 1, the case where there is an abnormality in the rotational torque is marked with x, and the case where there is no abnormality is marked with ○.

Each fixing belt according to Examples 1 to 9 and Comparative Examples 1 to 4 is basically manufactured based on the above-mentioned manufacturing method. The more detailed configuration and mode of each fixing belt are as follows.

<Example 1>
In Example 1, a mold having an outer diameter of 147 mm and a length of 340 mm and a material of SUS304 was used as a mold used for manufacturing the fixing belt. Further, the blasting process for forming unevenness and small unevenness on the inner peripheral surface of the fixing belt was performed using a "Pneumatic Blaster SFK-2" blasting device manufactured by Fuji Seisakusho Co., Ltd. Alumina particles of # 3000 were used for the primary blasting to form small irregularities, and # 120 zirconia particles were used for the secondary blasting to form irregularities with relatively large surface roughness. .. The rotation speed of the mold during each blasting process is 200 rpm, the blast particle ejection time and ejection pressure in the primary blasting process are 40 minutes, 0.1 MPa, and the blast particle ejection time and ejection pressure in the secondary blasting process are set to 200 rpm. It was set to 0.2 MPa for 20 minutes. Further, 4 g of dimethyl silicone oil "KF968" manufactured by Shinetsu Silicone Co., Ltd. was uniformly applied to the inner peripheral surface of the fixing belt.

<Example 2>
In Example 2, among the conditions of Example 1 above, # 30 zirconia particles were used for the secondary blasting. Other than that, the conditions are the same as those in the first embodiment.

<Example 3>
In Example 3, among the conditions of Example 1 above, # 100 zirconia particles were used for the secondary blasting, and the discharge pressure for the secondary blasting was 0.15 MPa. Further, as a lubricant to be applied to the inner peripheral surface of the fixing belt, fluorosilicone oil "FL100" manufactured by Shinetsu Silicone Co., Ltd. was used. Other than that, the conditions are the same as those in the first embodiment.

<Example 4>
In Example 4, among the conditions of Example 1 above, # 150 zirconia particles were used for the secondary blasting, and the discharge pressure for the secondary blasting was 0.5 MPa. Further, as a lubricant to be applied to the inner peripheral surface of the fixing belt, a fluorine oil "Demnum S-200" manufactured by Daikin Industries, Ltd. was used. Other than that, the conditions are the same as those in the first embodiment.

<Example 5>
In Example 5, among the conditions of Example 1 above, the particles used for the primary blasting are # 5000 alumina particles, the particles used for the secondary blasting are # 30 zirconia particles, and further, the secondary blasting is performed. The discharge pressure was 0.5 MPa. Other than that, the conditions are the same as those in the first embodiment.

<Example 6>
In Example 6, among the conditions of Example 1 above, the particles used for the primary blasting are # 2000 alumina particles, the particles used for the secondary blasting are # 30 zirconia particles, and further, the primary blasting is discharged. The pressure was 0.2 MPa, and the discharge pressure for secondary blasting was 0.5 MPa. Other than that, the conditions are the same as those in the first embodiment.

<Example 7>
Example 7 has the same conditions as those of Example 1 except that the particles used for the primary blasting are # 5000 alumina particles.

<Example 8>
In Example 8, among the conditions of Example 1 above, the particles used for the primary blasting are # 2000 alumina particles, the particles used for the secondary blasting are # 30 zirconia particles, and further, the primary blasting is discharged. The pressure was 0.2 MPa. Other than that, the conditions are the same as those in the first embodiment.

<Example 9>
In Example 9, among the conditions of Example 1 above, the particles used for the secondary blasting were # 30 zirconia particles, and the ejection pressure for the secondary blasting was 0.3 MPa and the ejection time was 15 minutes. .. Other than that, the conditions are the same as those in the first embodiment.

<Comparative Example 1>
Comparative Example 1 is the same condition as that of the above-mentioned Example 1 except that the discharge pressure of the primary blasting process is 0.02 MPa.

<Comparative Example 2>
In Comparative Example 2, among the conditions of Example 1 above, the particles used for the primary blasting are # 2000 alumina particles, the particles used for the secondary blasting are # 30 zirconia particles, and further, the primary blasting is discharged. The pressure was 0.4 MPa. Other than that, the conditions are the same as those in the first embodiment.

<Comparative Example 3>
Comparative Example 3 has the same conditions as those of Example 1 except that the particles used for the secondary blasting are # 2000 zirconia particles and the discharge pressure for the primary blasting is 0.02 MPa.

<Comparative Example 4>
In Comparative Example 4, among the conditions of Example 1 above, the particles used for the primary blasting are # 60 zirconia particles, the particles used for the secondary blasting are # 5 glass beads, and further, the primary blasting is discharged. The pressure was 0.7 MPa, and the discharge pressure for secondary blasting was 0.1 MPa. Other than that, the conditions are the same as those in the first embodiment.

As shown in Table 1 above, as a result of this test, the examples in which each surface roughness Ra of the small unevenness 31 is 0.05 μm or more and 0.4 μm or less, and the surface roughness RSm is in the range of 5 μm or more and 20 μm or less. In 1 to 9, no abnormality was confirmed in the initial rotation torque and the rotation torque after passing the paper. On the other hand, in Comparative Examples 1 to 4 in which the surface roughness Ra and RSm of the small unevenness 31 were not within the above range, abnormalities were confirmed in the initial rotation torque and the rotation torque after passing the paper. That is, by setting each surface roughness Ra of the small unevenness 31 to 0.05 μm or more and 0.4 μm or less and the surface roughness RSm to 5 μm or more and 20 μm or less, the wear of the fixing belt is reduced and the durability is improved. This is the result demonstrated by this test.

Although the embodiments and the respective examples of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments or the respective embodiments, and various modifications can be made without departing from the gist of the invention. Of course. Further, in the above-described embodiment, the free belt type fixing device in which the fixing belt is held by the belt holding members inserted at both ends in the longitudinal direction in a non-tensioned rack has been described as an example, but the present invention has described the fixing belt. Can also be applied to a configuration in which a belt is hung around a plurality of rollers and stretched.

Further, the present invention is not limited to the case where the present invention is applied to a fixing device which is an example of a belt device mounted on an image forming device. For example, the present invention can also be applied to a transfer device 8 (see FIG. 1) provided with an intermediate transfer belt 11.

9 Fixing device (belt device)
20 Fixing belt (belt member)
20a Inner peripheral surface 21 Pressurized roller (rotating body)
22 Halogen heater 23 Nip forming member 26 Heat transfer aid member (sliding contact member)
30 Concavo-convex 31 Small concavo-convex 41 Convex 42 Concave 100 Image forming device

Japanese Unexamined Patent Publication No. 2010-139935

Claims (7)

An endless belt member used in an image forming apparatus.
The inner peripheral surface of the belt member has irregularities and is
In the concave portion of the unevenness, there is a small unevenness having a surface roughness smaller than that of the unevenness.
A belt member having a surface roughness Ra of the small irregularities of 0.05 μm or more and 0.4 μm or less, and a surface roughness RSm of the small irregularities of 5 μm or more and 20 μm or less. The belt member according to claim 1, wherein the surface roughness Ra of the unevenness is 0.7 μm or more and 3.0 μm or less, and the surface roughness RSm of the unevenness is 150 μm or more and 400 μm or less. The belt member according to claim 1 or 2, which has a lubricant on the inner peripheral surface of the belt member. The belt device according to any one of claims 1 to 3, wherein the lubricant includes at least one of silicone oil, fluorosilicone oil, fluorine oil, and grease based on the same. The belt member according to any one of claims 1 to 4, and the belt member.
A sliding contact member that is in sliding contact with the inner peripheral surface of the belt member,
A belt device equipped with. With an endless fixing belt,
A rotating body that comes into contact with the outer peripheral surface of the fixing belt, and
A nip forming member that directly or indirectly contacts the inner peripheral surface of the fixing belt at a position where the rotating body comes into contact with the fixing belt.
Equipped with
A fixing device using the belt member according to any one of claims 1 to 4 as the fixing belt. The image forming apparatus including the belt device according to claim 5 or the fixing device according to claim 6.

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